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Dr. Brielmann Dear student and parents/guardians, Welcome to Chemistry! This packet contains 1. A syllabus 2. A student survey to be completed in class 3. A safety contract The safety contract must be signed and returned to me by tomorrow; students cannot begin lab work until it is signed and returned. Homework (5 points): Please have on your desk tomorrow, and each day 1. A 3 ring binder with this packet inserted (please do not use pockets). 2. A scientific calculator 3. A pen or pencil 4. Your completed homework: for tomorrow: this is your signed safety contract. 5. Read the story “How I got hooked on chemistry� which is in this packet.

Thanks in advance for your cooperation, Dr. Brielmann

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Introduction

Chemistry Dr. Brielmann Syllabus

Welcome to chemistry! I look forward to working with you this school year. The purpose of this handout is to summarize the goals, content, grading policy, and class expectations for this school year. What is everything made out of? That is the essential question for this course- the same question that the we all naturally ask as we look at the world around us. Finding the answers to this question is both challenging and rewarding. For a few of you, opening your mind to the world of chemistry may change the course of your life, as it did for me. For all of you this course will help you to understand the world around you. Content Here are the chapters we will cover. Each chapter will last for 1-2 weeks, and most chapters will be tested individually. 1. Introduction to Chemistry 2. Data 3. Matter 4. The Atom 5. Electrons

6. The Periodic Table 7. Chemical Bonding 8. Chemical Reactions 9. The Mole 10. Gases 11. Solutions.

12. Energy 13. Reaction Rates 14. Equilibrium 15. Acids and Bases

The System At the beginning of each of the 15 chapters shown above, each student will receive a packet to be inserted in your 3-ring binders. It includes everything you need for the chapter- labs, worksheets, and slides. You will also receive a textbook that you may keep at home for evening homework. At the end of the chapter you will be tested, and your notebook will be collected. Class Rules 1. Notebook open at the bell, homework out 2. Listen while others are speaking 3. Respect each other 4. No ipods, cellphones, food, or drink in classroom. These rules are in place to help promote a friendly, hard-working classroom environment.

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Common Issues 1. Late to class Students who are late to class without a pass will receive a minor point deduction on their next test. Three tardies will result in detention. 2. Arriving unprepared. Students who do not have a binder, calculator, and a pencil will receive a minor point deduction on their next test. Daily homework is worth 5-10 points. 3. Ipods and cellphones visible in class Ipods and cellphones will be confiscated if seen, and delivered to the student affairs center. You will be permitted to use internet capable devices such as iphones only when specifically requested by the teacher. 4. Lab Groups of more than 2 To receive credit for a lab experiment your group must be no more than 2 students. 4. Absences Unexcused absences are treated in accordance with the student handbook. Students are responsible for making up lost work and will still have to take each test. Makeups are available for students with a score of less than 70%. 5. Homework from other classes Will be confiscated if students work on it in class unless specifically instructed otherwise. 6. Students not seated or not in assigned seats Please remain seated in your assigned seat unless instructed otherwise 7. Unsafe laboratory practices This is a serious offense and will result in immediate removal from class and detention.

Grading Policy This class uses a “pure points” system: your grade will be determined by the points accumulated from homework, tests, and lab reports. For, example, you might earn 90 points on a 100 point exam, and 5 points on a 10 point quiz. Your average at that point would be 95 points out of a possible 110 total points for an “average” of 86%. Your grade can be accessed on PowerSchool through the GHS website, also available on the chemistryadventure website. During any type of testing, there will be no communications in any form with any other student(s). Should such communications take place, the student(s) will receive a grade of zero on the test. What to bring to class 1. An up to date 3 ring binder with chapters and homework. 2. A scientific calculator 3. A pen or pencil

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Homework There will be a moderate amount of homework assigned and posted to the right of the chalkboard, and on the chemistryadventure website most days. Please have it in your open binder on your desk completed at the beginning of class each day for grading. Most assignments will be checked at the beginning of the class the next school day for credit. No credit will be given for late homework. Keep up with the homework and the tests will likely go well. L1, Honors L1, Honors Conceptual Conceptual Read Problems Chemistry Chemistry Read Problems 1. Introduction to 1-11, 46-53, p. 31: 1 Chemistry p. 53: 1,2,4,5,7,11,12 2. Data 12-18, 55p. 14: 1-3 58, 63 p. 31: 6,7,8,9,10, 32, 35, 36, 37, 38 p. 59: 1-3 p. 63: 1, 2,3,4,5,6 3. Matter 22-27 4. The Atom 74-88 p. 89: 234-235 1,2,3,4,5,6,7,8 p. 236: 1,2 5. Electrons 90-98 p. 99: 1-11 6. The Periodic Table 116-122; p. 122: 1-14 124-131; 1-13 132-141 Optional: 142-147 7. Chemical Bonding 158-165 p. 165: 1-13 166-175 p. 175: 1-10 176-179 p. 180: 1-8 190-198 p. 198: 199-207 1,3,5,6,7,11,12,14 Honors p. 207:1-13 only: p. Honors only: 1-11 208-213 8. Chemical Reactions 9. The Mole 100-101 p. 102:1-4 224-233p. 103: 1-3 236-238 p. 228: 1-4 p. 229: 1-5 p. 230: 1-4 p. 233: 1-13

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p. 239: 1,2 10. Gases 11. Solutions. 12. Energy

38-45; 60

p. 45: 1,2,3,5,6,12 p. 61: 1-4

13. Reaction Rates 14. Equilibrium 15. Acids and Bases 1. Introduction to Chemistry 2. Data 3. Matter 4. The Atom 5. Electrons 6. The Periodic Table 7. Chemical Bonding 8. Chemical Reactions 9. The Mole 10. Gases 11. Solutions. Textbook The honors and level one classes are based on the textbook Chemistry (Holt Publishers), and the Conceptual Chemistry classes use the book Conceptual Chemistry. They will be handed out on the first day, and students may keep them at home for evening homework assignments. A set of class textbooks will be available. Students are fiscally responsible for the textbooks, which must be returned at the end of the school year in good shape. Absences and Makeup Tests If you are absent from class it is your responsibility to find out what you missed and make up any missing work. Daily and weekly lessons and homework are posted in class, and on the chemistryadventure website; this is where to find out what you missed. Contact me if you have missed class- you will still have to take the test. All students must take each test regardless of the number of absences. Even if you had multiple absences, give the test your best effort- at the very least it will help guide you for the makeup test. A makeup test is available to all students; scores will be averaged. To help invite your best effort on the first attempt, the makeup test is designed to be more challenging than the first test. Fiscal Responsibility

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Students are fiscally responsible for instructional equipment including laboratory materials and the textbooks. Ipods and Cellphones The school policy will be enforced- cell phones and ipods are not allowed in the classroom. They will be confiscated if they are seen at any time in the classroom. Media Privacy Occasionally there may be photographs or videos taken of us in the classroom. Although these are usually popular for the students and are good for the class morale, it is important for each student to know that their right not to be photographed or videotaped is important and will be respected. Additionally, any photos or videos that are taken in the classroom will never be shared outside the classroom. Each student was mailed a media privacy form at the beginning of the year. Please let me know if you prefer not to be photographed or videotaped. In the News We will begin each day of class with an In The News presentation by a member of the class highlighting any chemical discoveries that were made recently. These are brief presentations that are emailed to me the day before each presentation. For examples see the “In the news” section at chemadventure.com. Use the presentation I provide on the first day as a model for your own presentations. How to submit an “In the News” Presentation Create your in the news presentation using Wix or a similar website, and email an invitation to me at brielmannh@k12.ct.us

Final Note to students/Parents/Guardians Please contact me whenever (brielmannh@guilford.k12.ct.us).

you

wish.

I

prefer

to

communicate

by

email

Again, welcome to the world of chemistry. I look forward to working and learning and exploring with you this year. Dr. Brielmann (Dr. B.)

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Lab Safety Contract You and your parent must read and sign this contract before performing any experiments. Important addition: The internet, and YouTube in particular, may contain extremely hazardous videos that include explosions, fire and even bombs. Parents, please monitor your children carefully to be sure they never attempt to perform any at-home experiments- they can lead to severe injury or death. 1. The science laboratory can provide you with the exciting opportunity to do science. However, remember at all times that the laboratory is a place for serious work. Fooling around or disruptive behavior will result in removal from the laboratory. 2. Always prepare for an experiment by reading the directions for the experiment before you come to the laboratory. Follow the directions carefully and intelligently, noting all precautions. Note the MSDS (Material Safety Data Sheets) precautions for each chemical. Do not add to, omit or change any of the directions unless your teacher instructs you to do so. 3. Know the location of the Chemical Safety Policy and the MSDS. These include handling precautions, disposal techniques and other pertinent information as noted on the MSDS for each chemical. 4. Do only the experiments assigned or approved by your instructor. Unauthorized experiments are prohibited. 5. Read the label to be sure of the contents and information provided by the MSDS. Do not use any chemicals stored in unlabeled bottles. 6. Throw all solids and paper to be discarded into the chemical waste jar or other location directed by the teacher. Discard chemical waste as per MSDS instructions. Follow directions for recycling products of your experiments per directions from your instructor. 7. Never discard matches, filter paper or any other slightly soluble solids in the sink. Please clean the sink at the end of each lab. 8. Know the location of the eye wash, hood, blanket station, and the laboratory evacuation exit procedure. In the rectangle on the other side of this page, diagram the lab area noting the locations of all safety equipment, exits, fire alarms, etc. Note the location of the Chemical Safety Plan and MSDS envelope for experiments. 9. When working with corrosive materials, goggles, gloves and lab aprons must be worn throughout the lab period until ALL your classmates have completed the lab and the chemicals are safely stored. The rule for goggles is simple: If the instructor has them on, you should have them on, even if you have completed your experiment. 10. Do not touch chemicals with your hands.

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11. If acid or another corrosive chemical is gets in your eyes, wash with water for at least 15 minutes. Notify your instructor immediately. 12. Never taste a chemical solution. 13. No food (including candy or gum) or drink is allowed in the laboratory. 14. Sports cap drink bottles may be allowed (at teacher’s discretion) but may not be used during laboratory activities using chemicals. Never have a water bottle at a lab station. 15. When observing the odor of a substance, do not hold your face directly over the container. Fan a little of the vapor toward you by sweeping your hand over the top of the container. 16. Allow ample time for hot glass to cool. Remember that hot glass looks like cool glass. 17. Report any accident, even a minor injury, to your instructor. 18. Long hair must be tied back securely. 19. Never return unused material to stock bottles. Do not put any object into a reagent bottle except the dropper with which it may be equipped. 20. Keep your apparatus and work area organized. Avoid spillage, but if you do spill something, clean it up immediately using proper technique. Put your own equipment into your drawer and/or return any special apparatus to its proper place at the end of the period. 21. During clean-up time, attend to your assigned area duties. All duties must be completed before leaving the laboratory. Wash hands thoroughly with soap at the conclusion of each lab. 22. Respect your equipment and fellow laboratory workers. 23. Handle all spring-loaded and projectile devices with extreme caution to prevent accidental release or discharge. 24. Back packs and book bags must be stored under your table or on your chair out of the aisles to accommodate proper egress from the lab/classroom. 25. Students are not to work in a laboratory unless an instructor is present. All student experiments are to be done under the direct supervision of an instructor. 26. Open toe shoes/sandals and loose fitting clothing or jewelry are not permitted during specifically designated laboratory activities. Your instructor will notify you in advance of the activity. 27. Science department regulation states that safety goggles (flexible plastic with ventilating ports for chemical splash and glass breakage standard) must be worn by all students, teachers and

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visitors in the laboratory during work periods including clean-up time in accordance with State Statute. Science Department Policy and State Statute: “Any person who is working, teaching, observing, supervising, assisting or engaging in any work, activity or study in a public or private elementary or secondary school laboratory or workshop where the process used tends to damage the eyes or where protective devices can reduce the risk of injury to the eyes concomitant with such activity shall wear an eye protective device of industrial quality in the manner in which such device was intended to be worn.” In order to maintain a safe working environment, teachers are required to remove from the classroom any student out of compliance. I HAVE READ THE ATTACHED SAFETY RULES AND HAVE BEEN PRESENT WHEN THEY WERE DISCUSSED IN CLASS OR DIRECTLY WITH MY SCIENCE TEACHER. _____ YES, I HAVE ALLERGIES/SENSITIVITIES: Print Name ______________________ Student Signature _____________________Period ______________________ Instructor _________________________ Date _______________________ I HAVE READ AND DISCUSSED THE LABORATORY SAFETY RULES WITH MY CHILD. Parent Signature __________________________

Date _______________

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Name______________________________ Period_________ Chemistry Dr. Brielmann Student survey Parent/guardian names:________________________ ___________________ Your email address (please write neatly):_______________________________ What Science courses have you recently taken? Year____________________ Course ________________Teacher________ Year____________________ Course ________________Teacher________ Please fill out the following table: Definitely not interested

Not interested

neutral

Interested

Very Interested I am concerned about the environment I am concerned about meeting America’s future energy needs I am curious about hydrogen as an energy source I would like to know how a battery works I would like to learn about nuclear power I am considering a career in medicine I would like to learn about the chemistry of steroids I like to watch stuff explode

Do you have internet access at home? Yes / No. Can you access the internet at school? Yes / no Do you have interned access on your cell phone? (It’s ok if you do) What do you plan to do after high school? What colleges or universities are you applying to? Tell me a little about yourself.

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Notebook Check Throughout the school year your notebook will be checked weekly to help keep you organized, and to keep you from falling behind. This notebook will be a valuable reference in college, and I encourage you to hold on to it. It is critical, however that you do not share it with any students who may be later taking this course. Aside from the fact that it is considered cheating, it means they will not get the opportunity to discover any of the concepts and ideas for themselves. Your notebook will generally be collected on Fridays, and will be returned on Mondays. It will also be randomly collected during the year to help you keep it up to date, and for periodic grading of labs and worksheets. Please do your best to keep everything organized and follow these rules1. Make the front page your notebook check page, always. Reinforce the 3 holes. 2. Insert chapters, tests, and all class handouts chronologically: chapter 1 on top, chapter 15 at the end. 3. Do not use pockets. Everything must be punched and in the binder. 4. Complete all assigned worksheets and slides for credit. 5. Have the notebook opened to your completed homework assignment at the beginning of each class to receive credit. On the following page is your schedule for notebook checks. Please keep it at the front of your notebook so I can find it easily.

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Notebook Check Schedule: Please make this the first page in your notebook, always. Reinforce each of the 3 holes. Date

Score

Comments

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Chemistry

Chapter 1: Introduction to Chemistry How I got Hooked on Chemistry

In 1979 I took a course at the University of Connecticut called Advanced Organic Chemistry. Our Professor was Sam Huang, who gave us instructions on the first day and then we rarely saw him again. We were told we had to complete three experiments: 1. Identify an unknown pure chemical sample 2. Purify and identify 2 unknown chemicals in a mixture 3. Create a new chemical He gave each of us a vial with a liquid or a powder in it. We had three weeks to identify it. Mine was a shiny white solid. Under a magnifying glass it appeared as flat white plates. It melted sharply at 212 degrees Celsius. A big clue was discovered when I placed it under ultraviolet light- it glowed with a bright blue color. With this information I was able to correctly identify the solid as Anthracene, a constituent of coal. Next, he gave each of us another vial. We were told it was a mixture of two chemicals. We had three weeks to separate and identify them. This time the vial had a dull white powder in it. I watched as my lab partners set up complex chromatography and distillation devices and began tedious separations of their mixtures. Ugh. Under a magnifying glass two distinct crystals could Anthracene be identified- needles and plates. It took a couple days, but I was able to separate my mixture using a pair of tweezers and the magnifying glass, and identify each sample. Finally, we had the rest of the semester to make a new chemical. I got so excited about this one that I skipped spring break and spent it at the library. Yes, I had become a science nerd, big time. It was my first time reading real accounts of chemical research and I found it fascinating. Here people were creating chemicals to treat cancer, make bulletproof plastics, all sorts of projects ‌but what really interested me was the field of natural products- the study of natural, not manmade, chemicals. I found a research paper where the individual chemical that creates the main flavor of pineapples and strawberries was created in the lab. It was called furaneol, and I decided I would make my own version of it with a slight chemical change designed to give it a sweeter taste. The initial experiments were a disaster. There were chemicals I needed that weren’t in the O stockroom. My lab partners were goofing off while I was working with dangerous chemicals. And soon the deadline was approaching, but in the end I managed to make a small amount of a white solid, and the spectroscopic data matched the HO OH chemical structure. I realized that with enough effort any chemical one could imagine could eventually be made, and it seemed to me this was a powerful tool. I furaneol changed my major from biology to chemistry, and two years later I had my first job making chemicals designed to study cancer. In this class each of you will be given a similar opportunity to explore, imagine, and create using the chemical skills and knowledge from this class. In your first hands-on experiment you will be asked to create an artistic design using some safe, simple ingredients. By the time this class is near complete you will be ready to identify unknown samples and safely perform your own initial chemical research in a field of your choice. Our first chapter: Introduction to chemistry, will follow the following tentative schedule: Day 1: Introduction to Chemistry Introductions, hand out packet, water into wine demonstration, whoosh bottle demonstration, class picture, class rules.

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Day

Day

Day

Day Day

Homework: Get safety agreement signed by parents. Read “How I got hooked on chemistry�. Bring in 3 ring binder, pencil, and calculator 2: Chemical Rainbow Lab Notebook check, Homework check. Homework: Complete chemical rainbow lab. Prepare for notebook check 3 :Activity: The Periodic Table of Our Class Notebook check, homework check, distribute class pictures. Homework: Work on Periodic Table of our Class Posters; due date to be assigned in class. Complete Unit 1 Slideshow assignment on Chemistryadventure.com 4: Slideshow: Introduction to Chemistry Notebook check, collect Periodic Table of Our Class Posters. Homework: Complete Introduction to chemistry worksheet (WS 1.1) and Introduction to chemistry worksheet (WS 1.2) 5: Review Homework: Complete how to ace your first chemistry test worksheet; study for test. 6: Test- Introduction to Chemistry

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Day 1: insert flammability lab Name: ___________________________________Period: _____

Lab1.1

The Periodic Table of Our Class 30 Points Introduction: One of the biggest scientific discoveries occurred during the time of our civil war, when it was eventually determined that the universe consists of only about one hundred elements, and that they exhibit highly organized, periodic behavior. For example, elements number 2, 10, and 18 are inert and stable, while elements 3, 11 and 19 ignite when placed in water. Your task is to discover a similar periodicity for the students in this class. As an added challenge, three dimensional tables earn five bonus points. Directions: A form will be passed around in class to gather information about each student, and each of you will get a copy. Use this information to create an informative periodic table or our class. Grading will be based on: 10 points neatness: a superior poster has the same level of neatness as the periodic table in our classroom 10 points clarity: Obvious patterns exist throughout the table. The key is clear and brief, and like the periodic table, all organization is “global”, not “local”. This means that the patterns are throughout all rows and columns , not within each row and column. Ask me if you still aren’t clear. 10 points utility: A great class periodic table quickly shows obvious trends. For rectangular tables, the corners should show extremes. For example, one corner may show the oldest, most quiet student, and the opposite corner is the youngest, loudest student. This assignment must be completed and turned in on the date assigned. 1. You are an element. Fill in the information below and copy it on to the board. Name

Element Name

Element Symbol (Capitalize first letter

Age in days (16 years =5840; 17 years = 6205

Height in inches

Astrological Sign

Choose one: Boring Nerd Interesting fascinating Wild child

How loud are you? Quie t Mode rate Loud Reall y loud

How smart are you? Brain dead Not smart Smart Really smart Brillian t

Favorite musical style Rock Punk Grunge Rap Hip hop Other:

Dr. B

Beeenium

Be

18,396

67

taurus

nerd

mode rate

smart

rock

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3. Based on this information create a periodic table of our class. Note that the periodic table shows patterns for both rows and columns. Be sure to refer to the scoring guide and directions while creating your periodic table of the class.

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Name ____________________________ Period_____________ lab 1.2 Chemical Rainbow Experiment 14 Points Objective; Use the materials listed below to create a visually stunning display that shows as many layered colors as possible. Be sure to provide a repeatable procedure so that anyone in the class could repeat your experiment. This is our first chemistry laboratory experiment. It is designed to let you discover that 1. Chemistry is fun! 2. A good experimental procedure can be repeated by anyone 3. Understanding physical properties such as solubility, density, and viscosity allow us to predictably manipulate chemicals. You will receive one point for each separate layer of color, and five points for a repeatable procedure. The effort and reproducibility of your lab report (this paper) are also worth 5 points. The group that creates the largest number of separate layers gets 5 bonus points. There may be additional bonus points for creating other solutions- listen to the instructions. Materials (May vary) Corn syrup Shampoo Strawberry syrup Corn oil Mineral oil Here are things we tried, and the results: We tried:

Water Sugar salt graduated cylinders Food coloring

Clear cups Watch glasses

Results:

Here is our final repeatable procedure to create a _____-layer rainbow (create a clear numbered list):

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Discussion Solubility is the ability of one solution to dissolve in another. Example: Oil is insoluble in water Density is the mass of a substance for a given volume Example: Water has a density of 1 gram per milliliter; air is much less dense (0.001 g/mL) Viscosity is the resistance of a substance to flow. Example: Honey has a greater viscosity than water. Questions 1. Give an example of two substances in your experiment that are form an insoluble mixture (2 layers): ______________ and ____________. The sample with greater density is_________. 2. In this experiment, how does the density of your substance affect the results? _____________________________________________________________________ ____ 3. Is it possible for samples with a big difference is density to be soluble in each other?_______ 4. Two samples that are insoluble in each other can be made to form two layers, at least for a while, if they have a large difference in solubility/density/viscosity (circle one). Score: ____/4 layers + ____/5 for repeatable procedure + ___ bonus points + _____/4 questions= ________/14 points

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Introduction to

Intro video

1

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1. Why is chemistry awesome?

Name That scientist

Irene Curie 1935 neutron

Dorothy Crowfoot Hodgkin 1964 B12

End Unit 1 ď Š Barbara McClintock 1983 DNA

Richard Schrock 2005 catalysts

10. The big question: What is everything made out of? 8. Quantitative and Qualitative data 9. Precision vs. accuracy

7. The scientific method

Marie Curie 1903, 1911 radioactivity

5. What do chemists look like?

6. Branches of chemistry

2. What is chemistry?

3. What is matter? 4. What do chemists do?

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Name_____________________________Period____________

WS1.1

What is Chemistry? Worksheet Introduction: For this school year we will be investigating chemistry together. Perhaps we should start by thinking about the word. chemistry What thoughts does it bring to mind? One place to get a feel for a real world definition is to Google it. One of the first things that comes up is, well, dating sites. Chemistry seems to imply a proper mixing of things, which is nice. Others who have had exposure to it before think of strange topics like the mole, and labs where mixing things creates strange colors and smells. Hopefully by now you have learned by now that chemistry is the study of matter. This means chemists such as yourself want to know not only what everything is made out of (our essential question for the year), but also how to mix things together to create new substances. The mixing part is fun, but finding out what everything is made out of can also be exciting. For example, a natural products chemist in 1962 isolated an extract from a simple pine tree (the pacific yew) that contained the chemical taxol, now used extensively for the treatment of many forms of cancer. The word chemical also seems to have two definitions- the one that scientists use, and the way everyone else thinks about it. We will always use the scientific definitions, but it would be unrealistic not to consider other viewpoints. Scientists consider be a chemical to a pure substance. Any pure substance. Water, for example. But out in the world, most people think of chemicals as substances that are BAD for you.

Please answer these questions to the best of your ability. 1. What is chemistry?

2. What do chemists do?

3. List 10 chemicals: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10

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Name___________________________________Period____________

WS1.2

Introduction to Chemistry Worksheet Xiaozhang Zheng (his American friends call him Zang) is a friend of mine that worked for Neurogen, a small biotech company in Branford, Connecticut. Unfortunately they went out of business in 2008. He is a chemist that was part of a team working to develop a new pill for relieving pain. As of 2008 this medicine is in phase II clinical trials. The medicine is known currently as MK-2295, and it works in a brand new way, by docking into a receptor known at TRPV1. Here is your at-home homework assignment. Use the internet to answer these questions. 1. Describe the purpose of each of the FDA (US Food and Drug Administration) phases for experimental drug clinical trials: Phase I: Phase II: Phase III: Launch: 2. What is the status of MK-2295? Hint- you may want to try the following websites: http://clinicaltrials.gov/ct2/show/NCT00387140?term=mk+2295&rank=1 and http://clinicaltrialsweb.blogspot.com/2008/03/caution-recommended-following-studyon.html

On a typical day my friend Zang arrives to work in the morning, has a cup of tea, and does a computer search for any important scientific updates that relate to his field. Then he goes into the lab and checks on any chemical reactions that have run overnight to see if they are complete. To do this he will pull out a small sample (an aliquot) and have them analyzed on some instruments in a nearby lab. Then he will start some new chemical reactions to make some more research drugs for testing. Those that are complete he will take over to a nearby building where they will be tested on some animal cell lines to see if they are effective, and safe. As the reactions are cooking he will prepare some stock aqueous solutions that he routinely uses during the day. Before he leaves at the end of the day he will draw some of the molecules he is planning for the next day on his computer and the computer will predict whether those compounds are likely to be safe, effective, and whether anyone else has made them before.

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Use your class notes to answer the following questions: 1. When is Zang acting as A. A computational chemist? B. A medicinal or organic chemist? C. An inorganic chemist? D. A biochemist? E. An analytical chemist? 2. Which data is Zang likely to consider more important, the predictions from his computer, or the results of his animal cell lines? Why? 3. Is there any time during Zang’s research when he is not working with matter? Provide an example. 4. Give an example of a time when Zang is involved in a science that is more applied (less basic) than chemistry. 5. What is an aliquot? 6. Draw the OHEC cycle for the scientific method, and include an example from Zang’s work for each step that shows the scientific method in action.

7. When testing his chemical Zang will compare his reaction mixture to authentic samples of both his starting material and his desired product to be sure things are going according to plan. Which sample acts as a positive control? Which sample acts as a negative control?

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Name___________________________________ Period___________

howtoaceit1

How to Ace your First Chemistry Test Test 1 Unit 1: Introduction to Chemistry In this our first unit we were introduced to the world of chemistry. We began by asking ourselves what chemistry is, and what chemists do. As an example we showed how small chemicals can make large differences in color during the “water into wine” demonstration. We created a “Periodic Table of Our Class” to show how properties may be categorized. We also performed a solubility lab to introduce ourselves to observing and comparing the physical properties of some liquids. We then explored the branches of chemistry, and how chemistry fits in with the other sciences. We wrapped things up by reviewing a brief version of the scientific method, and the difference between accuracy and precision. In unit 2 we will explore data- how it is collected, and how it is analyzed. I’m sure you would all like to ace your first chemistry exam. Here’s how. 1. Test yourself on the topics below. 2. Review this packet in its entirety. Be familiar with each of the 10 topics that were covered in the powerpoint presentation. 3. Write down what you don’t know yet. If you don’t know something, ask a friend or ask me. 4. If you are missing anything it may be available on the class website: http://www.chemadventure.com note that the in-class material may be more recent than the website. This exam is based on in-class material. Topics: 1. What is chemistry? Chemistry is____________________ 2. What is matter? Matter is_____________________ 3. Branches of chemistry: organic, inorganic, analytical, medicinal, forensic, Physical a. organic: Organic chemistry is____________________ b. inorganic: Inorganic chemistry is___________________ c. analytical: Analytical chemistry deals with____________________ d. medicinal: Medicinal chemistry deals with___________________ e. forensic: Forensic chemists are all about__________________ f. physical:

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A physical chemist is only concerned with_____________________ In a physical change, ____________________________________ 4. The Scientific Method (OHEC): 5. Controls- negative and positive Negative controls ________________________. Example:_____________ Positive controls _____________________________ A control is a __________________________________ 6. Pure vs. applied science 1.___________2.___________ 3.__________ 4. ___________ 5.__________ 7. Qualitative and quantitative data Easy: Quantitative data involves_____________ 8. Accuracy and precision Accuracy:___________________ Precision:_______________ 9. Safety in the lab: where is the safety equipment? 10. What are meant by the terms solubility, viscosity, and density, and what how do they influence the mixing of solutions?

11. About how many elements are there, and what sort of periodic behavior do they have?

12. Level 1 only: You are responsible for the material covered in the “in the news� presentations. You should also be familiar with the work of Marie Curie : Irene Curie : Dorothy Hodgkin : Barbara McClintock: and Richard Schrock. Finally, for all students: Consider the positive and negative impact of chemistry on society.

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Additional topics 2008 13. Use words to complete the following chemical equations Methanol + ____________  ____________ + ______________ Propanol + _____________  ___________ + ______________ Magnesium + __________  _______________________

14. A yellow and a red solution are slowly combined. They form 2 fairly distinct layers with the red layer on the bottom. However when stirred they form one orange layer. What is going on in terms of density, viscosity, and solubility? Density: Viscosity: Solubility: 15. What is wrong with this chemical symbol: HB

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Data

1

In this chapter we will be looking at data. We will begin by designing and performing a Mentos Eruption Experiment, and will investigate throughout the week how to use the data that is obtained in a clear and meaningful way.

The tentative schedule for this unit is:

Day 1,2: Design Mentos Experiment. SI Units. Prefixes. Derived Units. Density. Temperature. Homework: Bring in mentos, soda and any other experimental aids Long term project: Research, outline Mentos Experiment Report- due:_______ Day 2: Initial Mentos Experiments. Scientific Notation (L1 only). Unit Conversions Homework: __________ Bring in additional mentos experiment supplies. Long term project: Continue writing Mentos Experiment Report- due ____________ Day 3: Final Mentos Experiments. Significant Figures (L1 only). Percent Error Bring in additional mentos experiment supplies. Long term project: Continue writing Mentos Experiment Report- due ____________ Day 4: Videotaped Mentos Performances. Review for Units 1 and 2 Test (Intro to chem, data) Homework: Complete How to Ace the Units 1 and 2 test. Review for Units 1 and 2 test Day 5: Test: Introduction to Chemistry and Data. Watch videotaped mentos performances Possible In-class time to continue writing Mentos Experiment Reports- due __________.

1


Name_________________________

Period__________

Lab2.1

Mentos Eruption Experiment 30 Points

Recently you observed the Mentos Eruption demonstration. In that demonstration, Mentos candies were added to soda, resulting in a violent eruption. Hopefully the demonstration made you wonder about what was going on during the demonstration. What causes the eruption? Does it have to be Diet Coke? Would more Mentos make the fountain go even higher? Would another type of candy work? Well this is your chance to answer those questions. Design an experiment based on your question, and you and your partner will perform it in class. Try to be creative- come up with an experiment that no one else is thinking of. 1. Effect of mentos temperature on the height of a mentos eruption Will an ice-cold mentos make for a really big eruption?? 2. Effect of soda temperature on the height of a mentos eruption -what would happen with near-frozen soda?? 3. Design of a remote-control mentos eruption -can you do create a remote control method? 4. Effect of nozzle size on the height of a mentos eruption -this can make for awesome special effects…think of fancy sprinklers 5. Design of a delayed mentos eruption -a tough one…it would work like a fuse…very safe 6. Effect of gum arabic on the height of a mentos eruption -everyone says its due to gum Arabic, but no one has ever tried it. 7. Determination of % CO2 using a mentos eruption -there must be a nice correlation 8. Effect of surface coating on the height of a mentos eruption -coat your mentos with something to double the height 9. Effect of nucleation sites on the height of a mentos eruption -I am so skeptical of this whole theory…I’ll bet it can be diproved 10. Effect of soda type on the height of mentos eruption -maybe there is a special soda out there 11. Pendulum effects based on the mentos eruption -and other eepy-bird type fun designs…makes for great video…perhaps a class performance is possible. 12. Mentos surface investigation Microscopic imaging has never been performed…Enhancement might be possible…An etched mento? Conceptual Chemistry Classes will demonstrate and video tape their final experiments. You will be graded equally on 1. Significance- did you discover anything new? Is your device or system useful? 2


2. Presentation- was your presentation to the class clear? Nicely rehearsed? Fun to watch? Is everyone clear what you are doing and why? 3. Awareness- has your experiment been done before? How do you explain your results? How does your device work? Level One Only: Your results will be published in The Guilford Journal of Chemistry; each of you will receive the most recent publication. Read it, and use it as a guide to determine your own experiments. Note that as for all scientific research, you must produce new and significant scientific results to be considered for publication in this journal. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Level One Only: The typed Journal report is due on the date specified. There will be a 10% deduction for each late day. The format is that of a typed scientific journal research article. Use the most recent Journal to assist you. You will be graded on the content in 10 areas: 1. Title 2 Your names. 3. A one paragraph summary of your experiment and results. 4. An introduction that summarizes what is known in your research area, with footnoted references. Use quality references such as that in previous Journal voumes. 5. An experimental section that briefly describes your experiment. If your experiment is design-based, (for example the design of a remote control system) each iteration can be described here 6. A results section. This must include a graph. SI units must be used. Scientific notation should be used when appropriate. 7. A conclusion section. This should include a discussion of the significance of the results, and suggested follow-up experiments. Be careful to be cautions in stating your conclusions, and support your conclusions with data. 8. An Experimental Procedure section. This describes your optimized procedures in a listed series of steps, and must be repeatable by a stranger. 9. A list of references should be the last section of your paper. Each reference must be cited in the paper. Web sites may be used, but scholarly works are considered preferable. These may include books or research articles, such as previous Journal articles. Consider using Google Scholar as a source for high-quality peer reviewed references. This is the hardest part. General websites such as Wikipedia may NOT be used. See the introduction to the journal for a good example. After the final rewrite, a printed copy will be turned in. Be sure to save your electronic version. This printed copy will be reviewed and returned with numerous improvements suggested. The revised version will then be graded and turned in and the final electronic copy only will be submitted to my dropbox. We will then use this to create the 2009 version (volume 3) of the Guilford Journal of Chemistry. Report due: ______________ Revised report and electronic copy due: _____________

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Please be sure to include all 9 items- it will be graded based on each item. Some ground rules and reminders: -As for all labs, safety is imperative. All experiments must be approved by me, and must be performed safely. Use a large tray to contain spills. Wear goggles. Do not perform experiments at home. You must supply your own soda and Mentos. Please bring some extra to help those who may need more.

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Names:

Period: Mentos Lab Report Form

Periods 1, 5,6: Hand In This Typed Completed Form by Thursday, September 18; save your file Period 2,3: Submit your Journal Article to my drop box by Friday, September 19. You may use this form to help you get started. Please divide the work between you and your lab partner to complete the following sections. You will be graded on the content in each area. 1. Title: One sentence that states what you discovered An excellent title quantitatively states a significant new discovery. Title: 3. A one paragraph summary of your experiment and results. Insert a nice picture of your experiment or the mentos eruption in general here. Add additional pictures wherever you want.

2. Your names By

3. Summary. A paragraph that briefly describes your discovery or invention. Be as bold as you can while still being able to fully defend the significance of your work. An excellent summary clearly states what you did and quantitatively discovered in a few sentences, comparing it to previous research. Summary:

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3. An introduction that summarizes what is known in your discovery area, with endnoted references. See the Guilford Journal of Chemistry, especially the introduction, for examples of useful references. The references go at the end of your report. An excellent introduction discusses relevant previous research in detail, citing at least 5 previous studies, and then connects it to the current study. Introduction

4. An experimental section that provides a listed procedure for your experiment. If your experiment is design-based, (for example the design of a remote control system) each iteration can be described here. An excellent experimental procedure should be written so that anyone could repeat it. Experimental 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. (add additional numbers if necessary)

6


5. A results section. Describe your results. This must include a graph. Periods 1,5,6: this may be handwritten. Periods 2,3: this must be computer generated. SI units must be used. Scientific notation should be used when appropriate. An excellent results section quantitatively (use numbers and percents) states the results using proper units, points out data that doesn’t fit and explains it, and compares results to previous published studies.

Results

6. A conclusion section. This includes a discussion of the significance of the results, and suggested follow-up experiments. Be careful to be cautions in stating your conclusions, and support your conclusions with data. 7


An excellent conclusions data analyzes all data including previous studies and states a brief significant quantitative conclusion. It should also hypothesize why the results are what they are. It should finish by suggesting what might be done next to further the state of the art in this area. Conclusions

7. A list of references should be the last section of your paper. Each reference must be cited in the paper. If you use a website it must be specific and discussed in the footnote- see The Guilford Journal of Chemistry for examples. These may include books or research articles, such as those in previous GJC articles. Consider using Google Scholar as a source for high-quality peer reviewed references. An excellent reference section should include at least ten relevant peer-reviewed references that are properly cited throughout the text. Websites should be briefly discussed to explain their significance. These should be cited in the text with superscripts for example like this. They should be then listed at the end of the report- these are your endnotes. Previous Guilford Journal of Chemistry references or other scientific journal articles are excellent references. Website references are generally unreliable because they are not peer reviewed, and use no experiments to support their explanations- this is no better than simply making something up. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. (add additional references if necessary)

Conceptual chemistry classes: Hand in a hard copy of this form. Level 1 classes: Use this form to generate a Guilford Journal of Chemistry research article and place the finished copy only in my dropbox. 8


9


Topic

Mentos Lab Report Scoring Rubric Read this to make sure you get a nice high score. Your Explanation Value Score

1. Title (10 points) Is present States what you discovered 2. Summary (10 points) Is present Summarizes the results Uses numbers or percents to get quantitative results 3. Introduction (10 points) Is Present Includes relevant references Explains the mentos eruption using only conclusions supported by verifiable experiments Is related to the experiment 4. Experimental Section (10 points) Is present Is repeatable by a stranger 5. Results (10 points) Are present with a graph Are described using numbers Are significant- you discovered something Do not contain suspect data 6. Conclusion Is present Discusses the significance of the results Is cautious: does not draw conclusions that are unsupported by the data Tries to explain the reasons for the results Suggests relevant follow-up experiments Total

5 5 5 5 3 2

2 3 3

2 5 5 3 2 4 1 3 3 2

1 1 60

1. Title does not state what was discovered 2. Summary only provides qualitative results (use numbers, percents, or factors like 3x) 10


3. Introduction accepts eruption explanations that have no experimental support. Be cautious. Note that most experiments that are performed by scientists who have not researched the topic first repeat known results, and so are a ). 4. Experimental procedure not repeatable (usually because numbers not used- what is the size of the bottle, the hole at the top, etc.) 5. Results not quantified 6. Results have suspect data 7. Conclusions make no attempt to explain results 8. Conclusions do not suggest meaningful follow up experiments 9. References from unreliable sources 10. References not cited in text 11. Fewer than 5 references provided.

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Names______________________________ Period______________ Mentosapprovalform Application to Perform a Mentos Experiment All groups should fill out this application form and submit it to their instructor for approval To be approved, all experiments must 1. result in a significant new discovery concerning the Mentos Eruption. 2. result in quantitative and repeatable results 3. be fun to watch 4. be guaranteed safe to perform 1. Briefly describe your experiment:

2. What will you discover that is new from this experiment?

3. How will you be able to quantify your results?

4. How will you demonstrate that your results are reliable and repeatable?

5. What controls (positive or negative) will you include in this experiment?

6. What will the viewers enjoy the most about this experiment when you perform it?

7. What are the safety issues and how will you address them?

approved

rejected

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13


14


15


16


17


18


19


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Name________________________Period______________Date_________

WS2.1

Worksheet 1: SI Units and Unit Prefixes Directions: Please answer the following questions to the best of your ability. Since you will be tested on this material soon, try to answer the questions without referring to your notes unless necessary. 1. Speed is often expressed in miles per hour. However, using SI units, speed (velocity) is expressed in ____________ per ________. 2. Volume is often expressed in ounces, however in SI units volume is expressed in _____________. 3. Fill in the chart below, using the above examples as a guide. Unit of measurement We usually use Length Mass Temperature density

But SI units require

4. I have a 40 gigabyte hard drive. How many bytes is that? 5. Terabyte hard drives are available…how many bytes of data do they hold? 6. Try to fill in the following table, only referring to your notes if necessary: Prefix Symbol Factor Scientific notation Giga mega 1,000 centi 10-3 micro n

example

Microgram

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WS2.2 Name____________________________Period__________________Date________________ Density and Temperature Worksheet Please note: -you must show your work for credit -you must include the units in your answer for credit Rearrange your formulas here: If d = m/v, then m = ______________ and v = _____________ Example. What is the density of a sample that has a volume of 12 mL and a mass of 19 grams?

D = m/v = 19 g/12 mL = 1 . 6 g/mL (level 1 students: note 2 significant figures)

1. What is the volume of a sample that has a mass of 21 g and a density of 4 g/mL?

2. A liquid with a mass of 14 g is placed in a 50 mL graduated cylinder. The water rises from 20 to 41 mL. What is the density of the liquid?

3. A solid material that is insoluble in water has a volume of 35 mL and a mass of 39 grams at room temperature. Will it float in water? (The density of pure water at room temperature is 1.0 g/mL)

4. Aluminum has a density of 2.7 grams per milliliter. What is the mass of a sample of aluminum with a volume of 150 mL?

5. The temperature in degrees Celsius is 273.15 degrees lower than Kelvin: K = 273.15 + C. Convert the following common Celsius temperatures to Kelvin: Room temperature: 24 oC Freezing point of water: 0 oC Boiling point of water: 100 oC Absolute zero: -273.15 oC: 6. Ethanol has a melting point of 150 K and a boiling point of 351 K. Convert these to degrees Celsius.

22


Name: _______________________________ Period___________ Date_______

WS2.3

Scientific Notation (Level 1 only) Please convert the following to scientific notation. Examples.

34,000 Red Sox fans; 0.0043 milliliters Solution: draw a line to make the number between 1 and ten, and adjust by powers of ten. 3

l 4,000 Red Sox Fans = 3.4 x 10

4

Red Sox Fans

0.004 l 3 milliliters = 4.3 x 10-3 milliliters

1. 0.000058 inches 2. 5,798 grains of sand 3. 854,231 Obama voters 4. 0.936421 seconds 5. 1,200,000 miles 6. 0.285438563 kilograms 7. 4.000000092 grams 8. 26 students Please convert the following to standard notation.

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Name: _______________________________ Period_________________

WS2.4

Unit Conversion Worksheet I This worksheet is designed to show how to convert units, and provides some assistance. We will be converting units throughout the year, so it is essential that you learn how to set up your equations and properly cancel units. Note that all unit conversions 1. Begin with what you are given (in this case 21 days) Solution: 21 days x 1 week = 3 weeks 2. Multiply by conversion factors to convert units 7 days (in this case 1 week = 7 days) -where the unit being cancelled is divided by itself so it equals 1 (days in the example above) 3. Units are cancelled to make sure everything is set up properly.

Example: How many weeks are in 21 days?

Instructions: Please fill in the blanks and answer each question using the same type of setup shown above. No credit will be given unless 1. Units are included in the setup and answer (weeks, days, etc) 2. Units are cancelled properly (days cancel in the above equation) 1. How many hours are in 4.5 days? 4.5 days x --- hours = ___ hours day 2. How many weeks are there in 31 days?

31 days

x

____ = 4.43 weeks ____

3. How many weeks are there in 42 days?

42 days

x

____ ____

= ___weeks

4. There are 2.54 centimeters in an inch. How many centimeters are in six inches?

6 inches __________ x = 15.24 centimeters 1 inch 5. How many weeks are there in 365 days? Please show all your work and cancel units.

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6. How many centimeters are in 9 inches? Please show all your work and cancel units.

OK, now a bit harder. Example: How many inches are there in a meter? 2.54 cm = 1 inch; 100 cm = 1 meter Solution: 1 meter x 100 cm x 1 inch = 39.37 inches 1 meter 2.54 cm 7. How many inches are there in 3.2 meters? Solution: 3.2 meters x ________ x ________ = ___ inches 8. How many meters are there in 650 inches? Solution: 650 inches x ________ x _________ = _____ meters 9. How many meters are there in 7000 inches? Solution: Finally, if you can do these you have mastered unit conversion. Example: If I am moving at 3 centimeters per second, what is my speed in inches per minute? Solution: centimeters per second can be written as centimeters Second And inches per foot can be written as inches minute 3 centimeters x 1 inch x 60 seconds = 70.9 inches Second 2.54 centimeters 1 minute minute 10. If I am moving at 25 centimeters per second, what is my speed in inches per minute? Solution: ____________ x __________ x ___________ = ___ inches Minute 11. If I am moving at 65 miles an hour and the speed limit is 100 feet per second, am I speeding? (5280 feet = 1 mile; 60 seconds = 1 minute; 60 minutes = 1 hour) Solution: Solution: 65 miles x ________ x _________ x ___________ = feet Hour second Therefore I am/am not speeding (circle one).

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12. Solve the following math problem by cancelling units. Be sure to include your units at the end 9 centimeters 2 seconds

x

1 inch 2.54 centimeters

x 60 seconds = 1 minute

_______

And by the way, 9 meters every 2 seconds is the same as ___ meters per second 13. Here’s a different one. Based on the math answer below, write the question that was asked. Example

Answer: 70 days x 1 week = 10 weeks 7 days

Question: How many weeks are there in 70 days?

Answer: 25.4 centimeters x 1 inch x 1 hour = hour 2.54 centimeters 3600 seconds Question:____________________________________________

.0028 inches second

14. What units would result from the following question? Example

centimeters day Answer: inches per hour

centimeters hour

x

x

inch centimeters

inches centimeters

x

day = __________ hour

x hour x seconds = __________ seconds millisecond

Answer: 15. The boxed example above converted from centimeters per day to inches per hour. Show how to convert from 1 mile per hour to meters per second (1609 meters = 1 mile; 60 seconds = 1 minute; 60 minutes = 1 hour) Show your work below:

Answer: 1 mile per hour is the same velocity as _____ meters per second. 26


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Name_________________________ Period_____________

ws 2.5

Unit Conversion Worksheet Two Note: this worksheet is all about showing your work. For each question show your work and cancel your units. Once we begin working with unfamiliar units like micrograms, you’ll be glad you learned how to set things up. Example: How many eggs are there in 5.25 dozen eggs? Answer:1. Start with what you are given. 2. Write the final units. 3. Multiply by conversion factors to get your answer. 5.25 dozen eggs x

12 egg = 1 dozen eggs

63 eggs

1. How many eggs are in 62.25 dozen eggs?

2. How many shoes are in 2048 pair of shoes? (Remember, it’s all about setting it up. No credit will be given to those who just put down the answer.)

3. There are 2.54 centimeters in an inch. How many inches are there in 342,342 centimeters? (Should you divide or multiply? If you set it up correctly it will show you what to do.)

4. There are roughly 1.6 kilometers in a mile. If I hike 100 kilometers, how many miles have I hiked?

5. If I travel at 32 kilometers per hour (32 km/hr), what is my speed in miles per hour?

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Name_____________________________ Period_______________

WS2.6

L1 only Worksheet : Scientific Notation (L1 only)/Significant Figures (L1 only)/Percent Error The first question in most sections has been answered for you ď Š 1. Convert each of the following into scientific notation. 727

______7.27 x 102________________

172000

_________________________________

0.000984

_________________________________

200.0 x 102

_________________________________

0.014 x 102

_________________________________

2,560,000,000,000,000,000,000,000,000,000,000 ______________________ (use 4 sig. fig.) 2. Convert each into decimal form. Note that some use improper scientific notation. 1.56 x 104 ______15,600_____________________ 3.6 x 10-2 _________________________________ 736.9 x 105 _________________________________ 0.0059 x 105 _________________________________ 0.00059 x 10-1 _________________________________

3. Calculate the following. Give the answer in correct scientific notation. a) 2.34 x 1065 + 9.2 x 1066

b) 313.0 - 1.2 x 103

4. Calculate the following. Give the answer in correct scientific notation. a) 8.95 x 1076/ 1.25 x 1056

b) (4.5 x 1029)(2.45 x 10100)

5. Give the number of significant figures in each of the following. 29


a) 1.05 g ___3__ b) 0.0003040 mm ______ c) 29000 + 10 ft ______ d) 0.90 x 1045 L ______ e) the number of eggs (12) that make up a dozen

______

6. Determine the answer for each of the following. Be sure to use the correct number of significant figures. a) 17.34 4.900 + 23.1

b) 9.80 - 4.762

c) 3.9 x 6.05 x 420 =

d) 14.1 / 5 =

7. Round each of the following to 3 significant figures. 77.0653 ___77.1___

6,300,178.2 ______________

8. Find the percent error. Example: I am measure to be 180.0 cm tall, but my real height is 195.07.692 cm. This measurement is off by 15/195 x 100 = 7.692% a. A police officer clocked me doing 78 miles per hour, but I am certain the correct speed was 65 miles per hour. He was off by ___ percent.

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Name_________________ Period_______

WS2.8

Cars of the Future Unit Conversion Worksheet Many people believe that hydrogen powered vehicles will eventually replace gasoline powered vehicles in the near future. Perhaps the most compelling point is that the combustion of hydrogen creates (in theory) only one product: water. General Motors, the world’s second largest auto maker, is investing heavily in this area. A big question is this: Where’s the hydrogen? Other people believe electric cars will replace today’s gasoline powered vehicles. These vehicles have no emissions at all for the vehicle itself; the energy is produced at the power plant and the car is filled up by transferring the electrical energy to the vehicle over power lines, either at home or at a fuel station. Are they better for the environment? Are the vehicles cheaper to operate?...Is electricity cheaper than gasoline? Recently, hybrid gas/electric vehicles became available and their numbers are increasing. Perhaps you’ve been in one. And the race is on to bring to market one of the most exciting options- a plug-in hybrid electric vehicle. These vehicles can be charged at home like your cell phone, and these cars may not use any gasoline at all for trips under 40 miles. If recharging is cheaper than a fill-up at the gas station, and the batteries work well, the day may come when most vehicles use this system. In 2007 GM announced plans to develop a special type of gas-electric hybrid. As opposed to a conventional gas-electric hybrid vehicle like the 2007 Toyota Prius, this series-hybrid vehicle is propelled only by an electric motor; the supplemental gas motor is used only to recharge the battery. Below are some questions based on real data for these types of vehicles. Use your unit conversion skills to find out the pros and cons of each type of vehicle. The first question is solved for you. 1. A Mercedes test vehicle could hold 1.8 kg of hydrogen and had a fuel economy of 45 miles per kg. How far could it go on a tank of “gas” in miles? In kilometers? (1.61 kilometers = 1 mile)

Solution: 45 miles/kg x 1.8 kg = 81 miles 81 miles x 1.61 kilometers/mile = 1 30 kilometers

2. My Toyota has a 12 gallon tank and gets 30 miles per gallon. How far can it go on a full tank of gas?

3. How many miles further can my Toyota go, compared to the Mercedes?

4. Honda has H2-powered test vehicle with the same fuel economy as the Mercedes, but with a 4 kg tank. How far can it go on a full tank? Can it go as far as my Toyota?

5. Hydrogen costs 5 dollars per kilogram. How much does it cost to fill up the Mercedes and the Honda?

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6. Gasoline currently costs $2.25 per gallon. Use this data and that from the questions above to find out which car costs the least for a fillup- the Mercedes, the Toyota, or the Honda?

7. Right now hydrogen-powered vehicles operate at 35% efficiency. The manufacturers hope to boost that up to 70% in three years. What would the driving ranges of the Mercedes and Honda be if that happens?

8. The top speed of the Mercedes is 87 miles per hour. For how many hours could one drive the Mercedes with the petal to the metal?

9. Each Mercedes right now costs $500,000 and they have made 19 so far. Based on that, how much money has Mercedes sunk into their project so far? Level One Only: Express your answer using scientific notation.

10. Ok, here’s the big question. We’ve seen that the Mercedes gets 35 miles per kilogram of fuel. How does that compare to my Toyota, which gets 30 miles per gallon? (Helpful conversions: 1 gallon = 4.2 liters; 1 liter of gasoline has a mass of 0.7 kilograms).

11. OK, here is my favorite question. I’ve heard that the plug-in hybrids are cheaper to operate, since electricity is cheaper than gas. Being a skeptical scientist, I hunted around for data to support this. I found all kinds of bizarre and useless data, but here is the key data that makes for valid comparisons. Our gas powered car gets 30 miles per gallon, and gas currently costs $3.20 per gallon. A Toyota prius consumes 0.253 kilowatt-hours (kwh) per mile, and the electricity costs 10 cents per kwh. Calculate the costs per mile for each vehicle. How do they compare?

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Name___________________________________ Period___________

howtoaceit1&2

How to Ace your First Chemistry test Test 1 Units 1 and 2: Intro to Chem/Data Analysis I’m sure you would all like to ace your first chemistry exam. Here’s how. 1. Test yourself on the topics below. 2. Review the notes, worksheets, quizzes, and the Mentos Eruption Experimiment and lab reports. 3. Write down what you don’t know yet. If you don’t know something, ask a friend or ask me. 4. For this exam pay particular attention to unit conversions and significant figures- they are the toughest topics to master. 5. Review the lessons using Dr. B.’s website: http://www.chemadventure.com Topics: 1. Data Analysis SI units: a. time,

2. Prefixes:

e. amount,

b. length,

f. density,

c. mass,

g. volume

d. temperature,

h. luminous intensity

a. giga, b. mega, c. kilo, d. deci, e. milli, f. micro, g. nano,

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h. pico i. List the units from pico to giga: 3. Density equation and problems: d = m/v

Example: What is the density of a substance with a mass of 2.4 grams and a volume of 3.2 mL?v True or false: The question above is a unit conversion problem. True or false: d = mv? True or false: v = md?

4. Kelvin to Celsius temperature equation and problems K = oC + 273

Example: 298 K = _____oC.

5. Scientific Notation (L1 only)

Example : Convert 6.2 x 10-4 to a regular number :__________

6. Percent Error a. What is the formula for percent error?

Example: If I have a mass of 142 pounds, but my balance says my mass is 152 pounds (ouch!), what is the percent error of that balance? 7. Unit conversion Show your work below :

a. 12 kg = _____g b. 3 hours = ________ seconds

c. 36 dozen eggs = __________ eggs

d. 25 miles = ____________ meters

e. 36 miles/hour = ________meters/second f. 3.2 x 10-23 picometers/year = _________miles/hour 8. Significant Figures (L1 only)

Example : 3.21 has ___ significant figures 34


Example : 3.201 has ___ significant figures Example : 0.321 has ___ significant figures Example : 3.210 has ___ significant figures Example : 3.21 x 2.4 has ___ significant figures Example : 3.21 + 4.234136 has ___ significant figures

Give the answers using the correct number of significant figures (L1 only) a. 3 + 2 = ________ b. 3.0 + 5.000 =________ c. 14.21 x 32.4809 =________ d. 15.5112123 + 4 =________ e. What is the volume of a piece of metal that has a mass of 3.2 grams and a density of 2.703 grams per cubic centimeter ? ________

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The Guilford Journal Of Chemistry Volume 1 Number 1 March 1, 2008 This issue is dedicated to the investigation of the well-known Mentos Eruption. Several discoveries are recorded for the first time in this issue, including: Cold Mentos increase the height of a mentos eruption A method for extremely long (1 minute) Mentos eruptions A method for remote-controlled Mentos eruptions A method for creating a “Mentos mist�


The Guilford Journal of Chemistry Dr. Harry Brielmann, Editor

The premier, state of the art venue for publication and broad dissemination of first-rate, fundamental research in all of chemistry and Mentos Research.

Contributors to the Mentos & Diet Coke Experiment Effect of Surface Coatings: Jennifer Agamie Carly Clark Different Carbonated Drinks and Mentos: Zach Brown Ethan Shore The Effect of Mentos Temperature: Rachel Cutler Emma Smith Diameter of Nozzle Size: Aaron Davis Travis Dillon The Effect of Diet Coke Temperature: Justin Husted Delayed Reaction: Stephanie Marsh Mike Moalli Remote Control Eruption: Paul Mulligan Jared Searles Spray Effects and Nozzle Shapes: Gabriella Necklas Kierstin Wall Fruity vs. Minty: Allessia Pascarella Johanna Penry Nozzle Effects: Taylor Smith Rosie Steffen

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Table of Contents Featured Paper #1 Mentos Eruptions are increased by heating or Cooling the Mints. By Rachel Cutler and Emma Smith Featured Paper #2: Creation of a “Misting Mentos” Eruption By Gabriellas Necklas and Kiersten Wall Featured Paper #3: Creation of a Remote-Controlled Mentos Eruption By Paul Mulligan and Jared Searles The Effect of Nozzle Size on the Height of Mentos Eruptions. Discovery of a method for thin, sustained eruptions By Aaron Davis and Travis Dillon Nozzle Designs Creat Spray Effects For Mentos Eruptions By Taylor Smith and Rosie Steffen The Effect of Soda Type on the Height of Mentos Eruptions By Ethan Shore and Zack Brown How the Coatings of Mentos affects the size of the Mentos Eruption By Carly Clark and Jenn Agamie Warm Soda has a dramatic effect on the Height of a Mentos Eruption By Justin Husted

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Introduction to this Issue This first issue of the Guilford Journal of Chemistry includes groundbreaking discoveries in the field of Mentos Eruptions. In its simplest form, the Mentos eruption involves dropping Mentos candy into a soda (usually diet coke), resulting in a foamy eruption, which can often be several meters in height. The first widely viewed Mentos eruption occurred on September 14, 1999 on the David Letterman show,1 though earlier eruptions using other candies (with less spectacular results) had been used primarily by teachers dating back to the 1980â€&#x;s.2 In terms of scientiic research this field is still in its infancy, since this area of research has almost no peer-reviewed published research results,3 although numerous videos documenting riveting eruptions are available on the internet,4 and on commercial television.5 Several unverified explanations have been offered to explain the eruption6, usually focusing on the physical shape of the mint (so-called nucleation sites), or on the various ingredients in the mint, particularly gum arabic. It is important to note that none of these hypotheses have been scientifically verified. This journal represents the first attempts to scientifically investigate the mentos eruption. Several previously unrepoted discoveries are documented in this journal. Perhaps the most fascinating discovery was made by Cutler and Smith.7 This featured papers reveals that that the height of a mentos eruption can be dramatically increased by freezing a mentos candy prior to dropping it in the soda. Coupled with the predictable observation that heating a mentos candy will increase the height of an eruption, this creates a bizarre result: the the height of a mentos eruption is relatively high when the candy is cold, low when the candy is at room temperature, and then high again when the candy is warm or hot. This discovery could in principle create world-record eruption heights (the current record is 29.2 feet). Another serendiptous discovery was made by Marsh and Moalli.8 While attempting to create a timedelayed Mentos eruption, they chanced upon a method for sustaining an eruption for over 40 seconds. More importantly, their graph suggests that this method could be applied to create eruptions that occur for several minutes in theory, though there were some occasional reproducibility issues that will have to be addressed. Several of these papers are design-based, in which an eruption of a certain type is desired and executed. Methods for creating several spectacular effects are published in this issue. Those interested in creating a unique misting effect should read the work of Necklas and Wall.9 Those looking for both an extremely high as well as a sustained eruption should turn to the work of Davis and Dillon.10 Space does not permit the higlighting of all articles. However, all of these investigations created spectacular eruptions and we hope you enjoy reading about them Dr. H. Brielmann Editor in Chief The Guilford Journal of Chemistry 4


References: 1. For an informative historical account of the Mentos Eruption, Speve Spanglers website is recommended: (http://www.stevespanglerscience.com/experiment/00000109. Note that the original Letterman Show Mentos Eruption may be viewed on the internet at http://www.chem.uic.edu/marek/letterman0/video/mentos.htm. 2. For accounts of Mentos-like eruptions dating back to the 1980â€&#x;s, see: Marek http://www.rimmkaufman.com/rkgblog/2007/12/21/steve-spangler/ 3. For example, the search term Mentos gives no results currently from polular scientific search engines currently (2008), including PubMed or Google Scholar. Online material is available from Scientific American (http://science-community.sciam.com/blog-entry/Sciam-Observations/SodaFountains-Diet-Coke-Mentos/300004196) as well as detailed hypotheses by the Royal Society of Chemistry (http://www.chemsoc.org/pdf/learnnet/classicdemos/mentosexplosion.pdf), but no experiments were performed in either case to test their ideas. 4. In addition to YouTube, other websites have arrived that are dedicated to the mentos eruption. Of particular mention is geysertube (http://www.geysertube.com/blog/), where one can view the Mentos Eruption in ultra-slow motion. 5. For example, on the popular television series Mythbusters (http://dsc.discovery.com/fansites/mythbusters/mythbusters.html). 6. Most literature on the Mentos Eruption cites the website of Fred Senese (http://antoine.frostburg.edu/chem/senese/101/consumer/faq/mentos.shtml), however there are no experiments performed or cited in support of these hypotheses.

7. Rachel Cutler and Emma Smith, Guilford Journal of Chemistry, Volume 1, Pages 6-12 (2008). 8. Steffi Marsh and Taylor Smith, Guilford Journal of Chemistry, Volume 1, Pages 13-16 (2008). 9. Gabriella Necklas and Kiersten Wall, Guilford Journal of Chemistry, Volume 1, Pages 33-35 (2008). 10. Aaron Davis and Travis Dillon, Guilford Journal of Chemistry, Volume 1, Pages 17-18 (2008).

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Mentos Eruptions are increased by heating or Cooling the Mints. By Rachel Cutler and Emma Smith

Introduction: Although there have been numerous experiments regarding the temperature of the soda versus the height of the explosion; we have found that there are no apparent results of the effect of the temperature of the Mentos in regards to the height of the explosion. 1Many people have conducted these experiments because it is fun to watch, and because it is quite interesting as to what makes the two create such a fantastic reaction. Most scientists say that it is the gum arabic that reacts with the soda and produces the desired result2. There may have been experiments done regarding this, but we have not found any results of those experiments. This had an effect on our experiment because we had no previous results to compare our findings to. But in a way this was also good, because it was as if we were the first ones who were discovering the effect temperature-changed Mentos had on Diet Pepsi. The reaction between Coke and Mentos usually produces a good reaction3, and although our experiment was modified it nonetheless produced good results. Summary: We wanted to see if the Temperature of the Mentos affected the height of the explosion when dropped into a bottle of diet Pepsi. We froze Mentos, heated them up, and kept them at room temperature to test the effects of each one, and then measured the height of the explosion of the diet Coke. Experimental Section: Our goal was to find which temperature most affected the soda, and would therefore create the biggest explosion. To do that we picked three different temperature areas to focus on: coldest, room temperature, and the hottest. We put one package of Mentos in a freezer, another sitting out in the room undisturbed, and another we wrapped in tinfoil and put on a hot plate. We then chose ten Mentos and put them into a graduated cylinder on top of an open bottle of Pepsi. I walked away after I opened the bottle of Pepsi, and Rachel ran away immediately after she dropped the Mentos into Coke. By doing this I was able to get the first look at how the explosion went, and then both Rachel and I were able to concentrate together once she ran away. We didnâ€&#x;t use any kind of nozzle because we were focusing on finding how the temperature of the Mentos affects the height of the explosion. We considered our negative control to be the neutral Mentos, which did produce a result, but not the one that we most desired. Our positive controls were the Mentos we either heated or froze. Through this we were able to compare the results of the positive controls to the results of our negative control. Overall, our experiment was one based not on design, but rather upon finding an answer through an experiment that produced results. Experimental Procedure: Materials: ~at least 3 bottle of Diet Pepsi ~at least 3 packages of Mentos ~2 meter- sticks 1

http://chemistry.org/education/chemmatters.html http://en. wikipedia.org/wiki/Diet_Coke_and_Mentos_eruption#Explanation. 3 http://en.wikipedia.org/wiki/Mentos#Mentos_and_soft_drink_reaction 2

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1. 2.

3. 4.

5.

~a bin to catch all the sodas if you are conducting the experiment inside ~towels to clean up the surrounding area, again if you are conducting the experiment inside ~tinfoil ~a hot plate ~a freezer ~a thermometer ~a graduated cylinder which youâ€&#x;ll put your Mentos in Procedure: Gather all the materials that is necessary for the experiment at hand Put 10 Mentos in a piece of tinfoil in a freezer, and keep them there as long as possible. Put another 10 in another piece of tinfoil and put on the hot plate; remember to keep checking the Mentos so they donâ€&#x;t melt, or worse, start a fire. And finally, keep another 10 Mentos out to absorb the surrounding temperature. Set up your experimentation area; with your soda in the bucket, and at least 2 meter sticks tied or taped together and put the 10 Mentos in the graduated cylinder. Have one person open the bottle of Coke, and the other person line the graduated cylinder up with the opening of the bottle. After the person who opens the bottle up is done with their job they should move in front of the area so they can see how high the explosion is. The other person should drop the Mentos into the bottle and run away as fast as possible so they donâ€&#x;t get wet. Continue the experiment with the other two packages of Mentos and soda bottles, and do as many experiments as possible so as to increase the validity of your results. Record your results as you go along in your experiment. Conclusion: Through this experiment we were able to realize and discover the fact the temperature of the Mentos does have an effect upon the height of the explosion. The Mentos that were heated to a degree of 313K reached a height of about two meters, or 200 centimeters. The Mentos that were kept at room temperature were about 303K; reaching a height of about 30 centimeters. Our biggest explosion by far was that produced by the Mentos that were frozen to a degree of 263K, and the force that the explosion hit the towel with was so great that it sprayed outwards. Because of that, we can only roughly judge that the explosion reached a height of 350 centimeters. Our results showed us that the temperature of the Mentos really does have an effect on the height of the explosion. Although our experiment did produce valid results there were a few errors along the way. Those included not all the Mentos falling into the Pepsi, and therefore not producing the full effect. We were also not completely exact in judging the height of the explosion, most of the time we had to make a quick estimate of where the peak of the eruption was. To make our results more valid we should have done more tests, which would have given us more support in the deduction that the more extreme the temperature the greater the eruption will be and more validity regarded the results we made. Overall, we were able to discover what we had initially wanted to find out; the temperature of the Mentos does have an effect upon the height of the eruption of the soda. However, to make our results more valid and better understood we should have done more tests; we also should have done more experiments because not all of the Mentos were dropped into the Pepsi which made the eruption results differ. However, we can concur that height is affected by temperature, and we are positive that if future tests were done regarding this, the scientists or whoever is conducting the experiment will find the same results that we found.

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8

0

50

100

150

Height of Explostion (Centimeters) 200

250

300

350

236K

Temperature (Kelvin)

303K

313K

The Effects of the Different Temperatures of Mentos in Diet Coke


Sustained Mentos Eruptions. Creation of a 40 Second Mentos Eruption by Mike Moalli and Steffi Marsh

Summary We tested coated mentos to see which coating would create the longest diet coke and mentos eruption. After testing our control, oil, sugar, molasses, and honey, we concluded that honey made the longest eruption of 40.28 seconds.

Introduction There is little to no information about how to delay the mentos reaction or how to make a prolonged mentos eruption. However it is believe that what causes the mentos and diet coke reaction is not a chemical reaction but a physical one. The gellan gum and gum arabic in the mentos dissolve and breaks the surface tension. This disturbs the water connection, so that it takes less work to expand and form new bubblesš. Each mentos candy has thousands of tiny pores all over its surface. These tiny pores function as nucleation sites for carbon dioxide bubbles to form. When the mentos enter the soda, bubbles form all over their surface. They quickly sink to the bottom, causing carbon dioxide to be released by the carbonated liquid with which they come into contact along the way. The sudden increase in pressure pushes liquid up and out of the bottle².

Experimental Section Our original experiment was to design a delayed mentos eruption. In order to do this we decided to coat the mentos in a variety of different substances to get the desired affect. Some of these substances including: honey, oil, molasses, sugar, salt, and others. We would coat three mentos in each of the substances and drop them into a small twelve ounce bottle of diet coke and then time how long the reaction was delayed compared to the control (three mentos that were not covered in any substances). After completing this we found that none of the substance had any significant delay in the reaction, however we notice that different substances gave a longer reaction. Using this newfound data we 9


retested some of the substances and timed how long each reaction was. After completing this we found that honey worked the best for creating a longer reaction.

Results Effects of Coatings on Mentos

reaction time (in seconds)

45 40 35 30 25 20 15 10 5 0

control oil sugar molasses honey control

oil

sugar

molasses

honey

types of coatings

control oil sugar molasses honey

7.17 7.89 10.32 30.18 40.28

Conclusion After conducting our experiments we have come to the conclusion that honey coated mentos work the best for a prolonged mentos and diet coke reaction. However our original experiment was inconclusive in finding a substance that delayed the mentos reaction. But in the progress of trying to find a substance that would delay the mentos reaction we found that some substance prolonged the mentos reaction by as much as 30 seconds. Some follow up experiment may include: the amount of honey used in covering the mento, break down honey into pure substance and seeing which substance in the honey is the main component in prolonging the reaction, and using different kinds of honey. Although we did not achieve our intended goal of making a delayed mento reaction, we believe that we have found something more useful and more fun overall.

1. a. b. c. d. e.

Materials 2 ounces of the following at room temperature: Sugar Molasses Honey Oil Water 10


2. 3. 4. 5. 6. 7. 8. 9.

1. 2. 3. 4. 5.

6. 7. 8.

9. 10.

11.

5 pieces of string each about 15 centimeters long 5 two liter bottles of diet coke At least 50 regular mint mentos Tongs Drill (to make a holes through the mentos) Pencil or pen and paper (to record results) Stop watch Towel

Experimental Procedure Take all of the mentos and drill holes though them. Put them in groups of ten and tie ten mentos on each of the five strings. Make sure they are tied close together so there is room to hold the string before you drop it into the bottle. Make sure to do this experiment outside where it‟s okay to make a mess of diet coke and mentos. The first test will be the control so there is no need to coat this sting of mentos in anything. Have your stopwatch ready because the string of mentos needs to be dropped into the bottle as soon as it is opened (to keep the carbon in) and the explosion will begin as soon as the string is dropped. Remember, you are testing how long the entire explosion takes to compare it to the other coated mentos. Open the bottle of diet coke and immediately drop the string of mentos into it. Stand clear at least three feet to prevent being soaked in diet coke. Once the diet coke reaction has stopped fizzing out the top, record your results. This time you‟re going to be testing the honey. Dip the string of mentos into the honey and use the tongs to make sure there‟s a nice thick coat of honey each of the mentos. Make sure to use a new bottle of diet coke and a new string of mentos each time you perform a trial because if either of them have been used for a previous trial, there will be no diet coke eruption. Now repeat steps 4-7 with molasses and then repeat the same steps with oil. Then skip to step 10. When you‟ve finished testing the control, honey, molasses, and oil, now test the sugar. Quickly dip your last string of mentos into the water before you coat it in the sugar. Again, repeat steps 4-7 with the sugar mentos, and then skip onto step 11. Once all the experiments are completed, use the towel to clean up any mess if needed. Don‟t forget to recycle the diet coke bottles.

References 1. 2.

http://en.wikipedia.org/wiki/Diet_coke_and_mentos http://www.stevespanglerscience.com/experiment/00000109

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Remote Control Mentos Eruption by Paul Mulligan and Jared Searles Manuscript in preparation. The Effect of Nozzle Size on the Height of Mentos Eruptions. Discovery of a method for thin, sustained eruptions by Aaron Davis and Travis Dillon The purpose of this experiment is to see if we use different nozzle sizes if it would affect the size of the eruption of diet coke when mentos is put into it. We believed that the smaller nozzle size we used the higher the eruption would go. When we conducted our experiment we were correct. When we placed 3 mentos into a 12 ounce diet coke bottle with no cap the eruption only went 8 centimeters high. Except when we put 3 mentos into a 12 ounce diet coke bottle with a 3 millimeter nozzle that the eruption went over 2 meters. We also tried with a nozzle size of 11 millimeters but the height of the eruption only went 61 centimeters. When we conducted studies on the height of diet coke eruptions when mentos is put into the coke we found out that the smaller nozzle size the higher the eruption and the longer the eruption will last. With a larger nozzle size the eruption will not go as high nor as will the eruption last as long. In our experiment we conduct an experimental procedure that focused on how different nozzle sizes of diet cokes will affect the size of eruption when mentos is put into the diet coke. We used 3 diet cokes with no caps, 3 diet cokes with 3 millimeter nozzle, and 3 diet cokes with 11 millimeter nozzle. We placed 3 mentos in each diet coke and measure the height of the eruption using meter sticks. In our experiment we found out that the smaller nozzle size the higher the eruption will go. We came to this conclusion because when we used a nozzle size of 3 millimeters we got our highest eruption of over 2 meters. The average of the eruption with a 3 millimeter nozzle was over 2 meters. When we did not use a cap at all the average height of the eruption was 6.7 centimeters, the lowest eruption we had. When we used a middle size nozzle of 11 millimeters we got a larger eruption then using no cap but a smaller eruption when we used a 3 millimeter nozzle.

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Procedure: Gather materials Take 3 12 ounce bottles of diet coke and open cap Place 3 mentos in each of the three bottles Measure the height of the eruption by using a meter stick Record the data you collected Repeat step 2 Take a drill and drill a 11 millimeter hole into all three caps Repeat steps 3, 4 and 5 Repeat step 2 Take a drill and drill a 3 millimeter hole into all three caps Repeat steps 3,4, and 5 http://eepybird.com/science.html http://eepybird.com/How%20To%20Do%20It%20Yourself!.pdf 12


NOZZLE DESIGNS CREATE SPRAY EFFECTS FOR MENTOS ERUPTIONS Taylor Smith and Rosie Steffen

Introduction: “The Mentos and Diet Coke Experiment” is caused when Mentos mint candies are dropped

into a bottle of a carbonated substance. The result is a jet of soda which spews from the neck of the bottle. The reaction is due to the rapid expanding of carbon dioxide bubbles on the surface of the candy. i

Experiment: In order to create a Mentos eruption, one releases a number of Mentos mint candies into a

bottle of Diet Coke. When the two elements of the experiment combine, they result in an explosion consisting of the carbon dioxide “fizz” of the Diet Coke. In this particular experiment, holes of varying sizes and patterns were drilled into the caps of the Diet Coke bottles prior to the release of the Mentos, thus causing the height and spray patterns to also vary. To enhance the height of the results, the holes drilled in the bottle caps must be smaller. When designing the experiment, drilling holes in a circular formation, created a fountain effect with the “fizz,” or by arranging the holes in a line formation, the “fizz” erupts in a similar fashion. In order to create a more horizontal effect of the spray, the holes should be drilled at an angle, pointing as much towards the opposite side of the bottle as possible. The holes cannot be drilled on the side of the cap itself; because of they would directly interfere with the cap‟s ability to hold onto the bottle, thus resulting with projectile qualities. In this particular experiment, the hole which created the highest and longest lasting spray effect was a single hole in the center of the cap drilled with a 4mm drill bit.

Conclusion: In this experiment, the best results were the single, 4mm sized

hole because the carbonation was so concentrated to a single are and therefore resulted in the highest height (6.09m or 20 ft.) and the hole which was drilled at an 8mm resulted in the lowest height (.9144m or 3ft.). This experiment could be modified for better results by applying further variations to the nozzle designs to better Caps with 8mm holes. shape the eruption and thus increasing the number of eruptions in order to achieve the desired effect. Caps with 4mm holes.

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Experiment Procedure:

Gather materials: 1 two liter bottle of Diet Coke (otherwise unflavored for best results), 1 package of at least ten mint Mentos, 12 cm of dental floss (or other string), a 5 cm (at least) thick piece of plywood, a 5cm roofing nail, a 4mm and 8mm drill bit, a power drill and two or three meter sticks. Step 1: Using the roofing nail, score ten Mentos by slightly applying pressure to the middle of the Mentos candy. Create a depression in the candy so that the drill bit will not slip off the Mentos when drilling. Do this for all ten candies. Step 2: Set up your drilling station by laying the plywood down. Ready your ten scored Mentos and begin to drill through them. Start by applying slight pressure downward on the candy while slowly drilling and only slightly increasing the drilling speed once the hard sugar coating is broken though. The speed increase after the coating, is necessary because the inside of the candy is gummy and a faster speed is needed to work through it. The candy might crack in half, do not use these because they could break apart during the experiment and cause a premature eruption. Repeat this process for all ten Mentos. Step 3: Drill the desired design in the bottle caps. It is better to collect other bottle caps and drill those because if the caps are removed from the test bottles, the carbonation in the soda will escape. Drill the desired designs in both diameters but on separate caps so that the height will vary. Remember that fewer holes in the caps create a greater concentration and therefore create the best results. Step 4: String your Mentos on the dental floss. Once you have completed that, take the string and thread it through one of the central holes in the drilled bottle caps. Step 5: Stand the three meter sticks end to end, vertically. Secure them as you see fit (duct tape is the best). Attach them to the Diet Coke bottle in the same fashion so that they will record the height of the eruption. Step 6: Open your test bottle and quickly remove enough soda so that when you screw on the drilled cap, holding the string of Mentos, the soda will not touch the candy resulting in a premature eruption. Once the drilled cap is securely on, hold the string of Mentos vertically and make sure it will not get stuck anywhere on the cap when it is released. Step 7: Before letting go of your sting, have a partner stand nearby to take pictures of the eruptions because this is a more accurate method of recording the eruption height. Step 8: Release your string and run!

(Repeat the procedure as many times as you wish, try varying the number of Mentos to achieve different heights.)

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The Effect of Soda Type on the Height of Mentos Eruptions

By Ethan Shore and Zack Brown

Summary: We tested the effect of different soda types on the height of mentos based eruptions in 2 liter soda bottles. We did 2 trials for each soda; Diet coke had explosions of .6 and 1.1m. Coke explosions of .1 and .15m . Sprite had explosions of .45 and .57m. Sprite zero had explosions of 1.1 and .95m. Sprite zero had the highest average explosion, with an average of 1.025m. Introduction: While many people have tried the Diet Coke and Mentos eruption experiment before, not many people have attempted to test different soda types with Mentos. However, the phenomenon was started by Steve Spangler, a science teacher, which got an explosion with Diet Coke and Mentos reaching 5.5 meters¹. He determined that as the rather heavy candy falls to the bottom of the bottle, carbon dioxide is released and the suddenly increased pressure pushes the liquid out of the bottle¹. One science class also attempted testing 44 different soda types on Mentos eruptions². Experimental: We tested each soda by opening the each bottle of soda, and then placing 5 Mentos inside the soda bottle, and then waited for the eruption. There were meter sticks behind the soda, so we could measure each eruption. We used 5 Mentos for each trial. Results:

The Effect of Mentos on Different Soda 120

Height

100 80

Trial 1

60

Trial 2

40 20 0 Diet Coke

Coke

Sprite Zero

Sprite

Soda

Conclusion: Based on our results, Sprite Zero causes the highest Mentos eruption with an average eruption of 1.025m. Diet Coke had the second largest explosion with an average of .85m. Sprite had the 3rd largest explosion, with an average of .51m. And Coke had the smallest average explosion, with an average of .125m. 15


This data was not 100% conclusive. During some of our trials, it was not clear whether all 5 Mentos made it into the bottle before the explosion occurred. Another factor lessening the conclusiveness of the results is the fact that after we dropped the Mentos in, we had to move out of the way very quickly. Sometimes, my hand partially hit an explosion, perhaps causing the height to drop. The results of this experiment were somewhat valid. Experimental Procedure Step 1: Gather 2, 2 liter bottles of Sprite, Diet Coke, Coke, and Sprite Zero. Step 2: Gather 40 Mentos, and a test tube (small enough for Mentos to fit in, large enough for them to fall out). Step 3: Take the plastic bin from the front of Dr. Bâ€&#x;s room, and place it at one of the back tables. Step 4: Tie 2 meters sticks together behind it, making sure that the sticks are straight. Step 5: Place a bottle of Diet Coke in the bin. Step 6: Place 5 Mentos in the test tube. Step 7: Open the bottle. Step 8: Drop the Mentos in the bottle. Step 9: Record the height of the explosion in your data. Step 10: Repeat steps 5-10 for Diet Coke once more, and each other soda twice more. References: šhttp://sciencecentered.blogspot.com/2007/04/mentos-and-diet-coke-geysir.html ²http://www.geysertube.com/blog/

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How the Coatings of Mentos affects the size of the Mentos Eruption by Carly Clark and Jenn Agamie Introduction: For our experiment we decided to test the different effects of mentos coatings on diet coke to see the different heights of eruptions. To test our theory we used a control, which was the regularly coated mentos, mentos without any coating, and mentos drenched in dish soap. After three trials we were able to clearly see that the regularly coated mentos had the best eruption by far. Summary: Throughout our experiment we concluded that the non-coated mentos had the worst height. The average height in centimeters after three trials was only 33.33 cm. This shows that there was hardly any eruption at all. The mentos soaked in dish soap averaged to be 58.33 cm, which is better than the non-coated but still not superb. Finally, we were able to test the regular mentos and received an average height of 230 cm. We made sure to use exactly ten mentos per liter of diet coke so that we had a constant throughout our experiment. Experimental Section: The design of our experiment was to see what actually made the mentos in the diet coke to erupt. After several ideas were tossed around we decided to see if the coating had anything to do with the eruptions. In order to test this idea we de-coated ten mentos and covered ten more in Dial dish soap. Then we gathered ten more mentos and left them with their regular coating. Instead of stringing the mentos onto a wire and dropping them into the diet coke bottles we decided to place all ten of them into a graduated cylinder and hold a thin piece of paper over the opening. We flipped the graduated cylinder upside down so that the opening covered with paper was lined up to the top of the diet coke bottle. We tried to let as little carbonation out of the bottle as possible, so that there was more of a reaction. Procedure: 1. First, we gathered our materials, which consisted of a graduated cylinder, 3 liters of diet coke, and 2 packages of mentos. We also used dial dish soap, a beaker, and thin pieces of paper, two-meter sticks, and a bucket. 2. Then we made three piles of ten mentos. One set we covered in soap, then next set was regular, and the third we soaked in a beaker full of hot water so that the coating would dissolve. 3. After the mentos were ready, we placed one liter of diet coke in the bucket so that when the eruption occurred soda wasnâ€&#x;t sprayed everywhere. 4. Next, we taped two-meter sticks together and tied them around the diet coke bottle so that we were able to see the height of the eruption. 5. Then one of us held the graduated cylinder upside down above the top of the bottle. While the other person unscrewed the cap. 6. As soon as the cap was unscrewed the person holding the graduated cylinder moved the paper and released the mentos into the diet coke. 7. We made sure to stand far enough from the eruption so that we wouldnâ€&#x;t get soaked in soda, but close enough to see the height of the eruption. 8. Once each different type of mentos underwent the experiment we recorded our data into a table. 9. We performed the experiment two more times. Each time recording our data to make sure the height 17


was accurate. We then averaged the height of the different mentos to see the results as one. 10. Once each trial was through, we cleaned our station and compared our results to our hypothesis. Conclusion: After having tested our experiment many times we came to a conclusion that the mentos with the regular coating had by far the best eruption. While it averaged in 230 cm the other two only went up to 58.33cm (soap), and 33.33 cm (non-coated). As we thought, there is something in the coating of the mentos that effects the eruption. During our experiment we were very much in awe to see that the two mentos that were changed had such a low height.

References:

1.”Mentos Geyser.” Making Science Fun. Feb.10, 2008. http://www.stevespanglerscience.com/experiment00000109. 2. “Diet Coke and Mentos Eruption.” Wikipedia, the Free Encyclopedia.Feb. 10,2008 http://en.wikipedia.org/wiki/Mentos-eruption. 3. „How to Make a Soda Bottle Volcano.” Extreme Diet Coke and Mentos Experiment, Wikihow. Feb.11, 2008 http://www.wikihow.com/make-a-soda-bottle-volcano.

The Effects of Different Mentos Coatings in Diet Coke

300

200

Series1 Series2 Series3

150 100 50 Averages

Regular Coated Mentos

NonCoated Mentos

0 Soap mentos

Height(cm)

250

Different Coatings

18


Warm Soda has a dramatic effect on the Height of a Mentos Eruption by Justin Husted While numerous experiments have been done with the coke mentos eruption, sometimes called the coke mentos geyser or rocket, very few have tried testing the effects of the temperature of soda before adding the mentos. Some brave experimenters have come to the conclusion that the reaction rate appears to double for every 10 degrees Celsius that you heat the diet coke. Similarly for every 10 degrees that the soda is cooled (or frozen) the reaction power and height is cut in half. 4 Also according to www.stevespangler- science.com, the temperature of the soda greatly affects how much force and height the geyser of soda fizz will shoot up to.5 My goal is to duplicate their experiments in an attempt to find if the temperature of the diet coke actually affects the height of the mentos eruption. The Experiment: By submerging bottles of coke into different water temperatures, we can safely control the temperature of the soda inside. The three temperatures being used in this experiment are cold, (262 K) room temperature (298 K) and warm diet coke (approximately 308 degrees K). Using eight mentos in each bottle, they will be set up to erupt and see which yields the biggest eruption. Summary of findings: The results of the experiment were clear and as expected. The coldest coda resulted in the small and shortest eruption of diet coke. The room temperature soda had expected results and was a relative increase from the cool soda. The warm diet cokeâ€&#x;s results sky-rocketed. Of the two warm test trials, both blast the coke into the air with a large amount of force, resulting in an average height more than double what the room temperature soda achieved. Conclusion: At the conclusion of this experiment I found that, as expected, the warmest soda temperature produced the biggest results of the three. The coldest soda temperature barely erupted out of the bottle. The cold soda was submerged in water measured at 263 degrees Kelvin. After putting in eight mentos, the following eruption resulted in about 20 centimeters of height. The next largest was the soda that was left in the classroom for two days to ensure it was the average temperature of the room. The temperature was measured at 298 degrees Kelvin. The resulting eruption was approximately one meter exactly. (100 centimeters). The final trial was of the warmest soda was that which was heated in water measured at 308 degrees Kelvin. The resulting reaction resulted in an eruption of 300 centimeters (three meters). By the results of the data, it is easily safe to conclude that the warmer the diet coke temperature, the more height the eruption gained.

Experimental Procedure: The following steps will lead to the exact duplicate of the above experiment. 4

Username: “Labmonkey� Yahooanswers.com January 10th, 2008

5

www.stevespanglerscience.com, mentos and soda temperature.

19


1) 2) 3) 4) 5) 6) 7) 8)

Obtain materials, needed is: three 2 liter bottles of diet coke, exactly 24 mentos candies, a thermometer, meter sticks, and glass cylinder containers to house hot and cold water. Submerge one sealed bottle of diet coke into a cylinder of cold water, measured at 262 degrees Kelvin. Leave in for at least ten-twenty minutes. Submerge a second bottle into warm water. Use the thermometer to measure the temperature of the water to 308 degrees Kelvin. Leave in for ten-twenty minutes. The third and final bottle should be left in normal room temperature conditions (approx. 298 degrees Kelvin) Set up a measuring system of at least two meters sticks in a container to catch the spraying coke. Tape or string should be used to attach two sticks together. Using a graduated cylinder to house eight mentos, un-attach cap of the first bottle and drop mentos inside, stand back, observe and measure height using meter sticks. Repeat step six for the remaining two bottles of diet coke. Use exactly eight mentos each time and record each height in a table for future reference. Graph and conclude data.

20


Creating a “Misting Mentos Eruption” By Gabriella Necklas and Kiersten Wall

Summary: For our experiment we tested how the shape of the opening that the soda sprays through affects the height of the geyser. Our goal was to determine which nozzle created the greatest height. From our experiment we were able to conclude that the smaller the hole the higher the geyser created. We were also able to see that a circular shape works better than a slit in the cap does. Introduction: In the field of Mentos eruptions there is still some debate over how the reaction occurs. However, there is one relatively accepted reason for the reaction. “When you drop the Mentos into the soda, the gelatin and gum arabic from the dissolving candy break the surface tension. This disrupts the water mesh, so that it takes less work to expand and form new bubbles. Each Mentos candy has thousands of tiny pits all over the surface. These tiny pits are called nucleation sites - perfect places for carbon dioxide bubbles to form. As soon as the Mentos hit the soda, bubbles form all over the surface of the candy.” ii It is also well noted that a substance under pressure that is forced through a small hole will go higher than the same substance through a substantially larger hole. This is how we came to the hypothesis that our small hole would produce the largest geyser. Experimental Section: For our experiment we conducted two trials. Each trial followed the same procedure, our goal was to try and get the most accurate results possible. We dilled a hole into the center of each mento and then strung 10 mentos for each nozzle type. We then pulled the other end of the string through the nozzle so that the mentos would hang below the nozzle and into the bottle while we had about a two inch portion of string to hold onto until the designated time for eruption. We also attached two meters end to end and staked them into the ground behind our soda bottles in order to measure our eruptions. Once all of these preliminary steps were taken care of we screwed on the nozzle that was being tested and let go of the string in order to release the mentos into the Diet Coke. Results Section: 21


Nozzle Type Trial 1 Trial 2 Control 1 meter 1.2 meters Small Hole .7 meters About 3.5 meters * Straw .5 meters 2 meters Small Slit .2 meters 1.5 meters Measurements have been rounded. *Our measuring device only went up to two meters, for this measurement we had to estimate its final height. Our first trial is significantly different than our second trial for all of our experimental nozzles because of a malfunction we had with our release cord. For our second trial we were able to fix the problem and our results are much larger because of it. Conclusion: Our results conclusivly show that the small hole is the optimum nozzle size to produce a large geyser. The small hole went 1.5 meters higher than its closest rival, the straw. Even though the straw and the small holeâ€&#x;s openings had the same diameter they both had drastically different results, we believe that the length of the straw affected the height of the geyser. Also while the small slit did manage to go higher than the control, by only .3 meters, we were able to see that at a certain point the hole becomes too small for the geyser and it has the affect of creating a much shorter eruption. We noticed during our trial of the small slit that more of the soda was coming out in a mist like fashion creating a much shorter and less impressive eruption. For follow up experiments it would be a good idea to try nozzles of different lengths. For instance cutting a straw into three different lengths in order to see if it was really the length of the straw that caused it to create a shorter geyser than the small hole. Another possible follow up experiment would be to have holes that gradually increase in diameter to check if the small slit really was too small and if the small hole really is the optimum size.

1. 2. 3. 4.

5. 6. 7. 8.

9. 10.

Procedure: Gather 8 two liter bottles of Diet Coke, 4 boxes of Mentos, string, a drill, a straw, and a pastry nozzle used to make ribbon like lines. Drill a Âź inch hole into a soda cap, this will be the small hole nozzle. Drill another Âź inch hole into another soda cap and insert the straw into the hole so that when the cap is screwed onto the bottle the strawl will stick up on the outside. This will be the straw nozzle Now drill a hole into another cap that is large enough to fit the pastry nozzle. Then insert the pastry nozzle into the hole so that when the cap is screwed onto the bottle the nozzle is on the outside. Hot glue the pastry nozzle into place so that no liquid can escape. This will be the small slit nozzle Now drill a hole into the center of 80 Mentos, this will be enough for both trials on each nozzle. Tape two meter sticks end to end and stake them into the ground so as to measure the eruptions. Place an open Diet Coke infront of the meter sticks. String 10 drilled Mentos and hold them so that only the bottom two Mentos are in the neck of the bottle. Count down from three and drop the Mentos into the soda. Record the eruption, this will be your control. Repeat step 8 for the second trial of the control. Now string another 10 Mentos. Run the top of the string through the small hole and screw the small hole nozzle with the mentos dangling beneath it onto a new Diet Coke bottle, make sure that the Mentos will not touch the diet coke, you may need to pour out some soda. Place the ready bottle infront 22


11. 12.

13. 14.

15. 16.

of the meter sticks and count down from three then drop the Mentos into the soda and record the eruption.This will be your small hole trial. Repeat step 10 for the second trial of the small hole. Now string another 10 Mentos and run the top of that string through the straw nozzle. Screw the nozzle onto a new Diet Coke bottle so that the mentos hang below it, make sure they do not touch the soda, you may need to pour some soda out. Place the readied bottle infront of the meter sticks and count down from three, then drop the mentos into the soda and record the height. This will be your straw trial Repeat step 12 for trial two of the straw nozzle. String another 10 Mentos and run the top of the string through the small slit nozzle. Screw the small slit nozzle onto a new bottle of Diet Coke so that the mentos hang inside the bottle, make sure they do not touch the soda, you may need to pour some soda out. Place the bottle infront of the meter sticks, count down from three and let the Mentos fall into the soda. Record the geyser, this will be your small slit nozzle trial Repeat step 14 for trial two of the small slit. Clean up the workspace. Gabriella Necklas and Kierstin Wall

i

“Diet Coke and Mentos Eruption,� http://en.wikipedia.org/wiki/Diet_Coke_and_Mentos_eruption

ii

http://www.stevespanglerscience.com/experiment/00000109

23


The Guilford Journal Of Chemistry Volume 2 October 1, 2008 This is our second issue dedicated to the investigation of the well-known Mentos Eruption.


The Guilford Journal of Chemistry Dr. Harry Brielmann, Editor

The premier, state of the art venue for publication and broad dissemination of first-rate, fundamental research in all of chemistry and Mentos Research. Volume 2

Table of Contents Featured Paper #1 A Four-Way Remotely Controlled Simultaneous Release Mechanism for Diet Coke and Mentos Eruptions by Ryan Johnson and Will Graziano Featured Paper #2: Diet Pepsi – Not Diet Coke - Results in the Highest Mentos Eruption When Compared to Other Diet Carbonated Drinks By Angelise Musterer and Lindsay Ruotolo Featured Paper #3: Cinnamon Mentos Eruptions are 20% Higher than Mint Mentos Eruptions By Allison Federici and Jess LaChance A Time Delayed Diet Coke and Mentos Experiment By Mike Amento and Scott Leone Volumes Effect on a Mentos Explosion By Kaitlyn Earles and Megan Graham Six Meter Coke and Mentos Eruption Achieved by Heating the Bottle By Mary Melillo and Artem Guryanov Eruptions Caused by Mentos Increase with Smaller Nozzle Sizes By Holly Aery and Adam Sierzputowski

2


Comparable Reaction of Diet Coke as Opposed to JOLT Energy By Dylan Klett and Trevor How the Amount of Mentos Affects the Height of the Eruption By Matt Feldman and Alex Monte Communications Discovery of the Worlds Longest Mentos Eruption: One Hour and Forty Minutes.

By Sam Taylor and Will Schaffer

Drilling a 5 mm Hole in a Mentos Candy Results in a 20% Increase in Eruption Height.

By Nick Hill and Kyle Gaboury

Cold Soda Increases the Height of a Mentos Eruption

By Andrea Cawley, Morgan Ehrler, and Pam Salmeron

Mentos Sliced in Half will Double the Height of a Mentos Eruption Karo Syrup Quenches the Mentos Eruption Serendipitous creation of a Mentos Rocket

By Emilyâ€&#x;s Ring and Kipness

By Kelsey Robins and Laura Turcio By Alex Jagielski and Eric Hedberg.

.

3


Introduction to the second issue of the Guilford Journal of Chemistry Like the first volume,1 this second volume of The Guilford Journal of Chemistry includes groundbreaking discoveries and applications of the mentos eruption. Prior to the publication of the first volume of this Journal, numerous theories have been purported to explain the science behind the Mentos Eruption2. These sources have been analyzed by numerous students, and with the single exception of the well known Mythbusters investigation3, no significant experiments had been documented, a deplorable condition considering the popularity of this phenomen. The first issue of this Journal documents the first publication of peer-reviewed research in the Mentos Eruption. Several exciting discoveries were made, including the bizarre observation by Cutler and Smith4 that both cold and warm mentos will increase the height of a mentos compared to a standard room temperature eruption. Other studies created long sustained eruptions,5 and numerous special effects were demonstrated, including a remote-controlled eruption device by Mulligan and Searles.6 All of these discoveries were tested in this second volume, and numerous new discoveries were found. Numerous investigators designed experiments to confirm (or invalidate) the unique results of Cutler and Smith. It was confirmed by most but not all of the investigators that either heating or cooling a mentos will increase the height of an eruption. A careful, convincing study is badly needed to confirm or reject this observation. This also led to a accidental discovery by Taylor and Schaffer7: A melted mentos will erupt at a very slow, sustained rate, continuing for nearly two hours. Two careful studies refuted common mentos assumptions. It is widely assumed that mint mentos produce the highest eruptions. In fact Federici and LaChance8 found that cinnamon mentos will create an eruption that is 20% higher than mint mentos. Perhaps one of the most widely assumed conclusions is that diet coke creates the highest eruptions of all carbonated beverages. However, Musterer and Ruotolo9 found that Diet Pepsi is the soda of choice, creating an eruption that is, amazingly, over 100% higher relative to diet coke. This important discovery needs independent confirmation. A creative study by Earles and Graham10 suggests that the power of an eruption should not be measured by eruption height, but rather by the volume of the eruption. Interestingly, the remaining volume of soda for a variety of soda sizes was constant, suggesting that there is a fixed relationship between soda size and eruption volume. One of the most surprising results concerns the work of Kipness and Ring,11 who found that a mentos cleanly sliced in half erupts higher than a whole mentos. A similar conclusion was determined by Hill and Gaboury,12 who determined that a drilled mentos erupts higher than a normal mentos. What is this due to? It is our hope that the researchers of Volume Three of the Guilford Journal of Chemistry can sort this out.

4


Among numerous others, two other studies merit mentioning here. A study by Robins and Turcio13 designed to use the power of the mentos to simulate a volcanic eruption instead accidentally discovered that the reaction can be entirely quenched by an additive. However, it was never finally determined if the effect is due to corn syrup or red food dye. Finally, in a featured paper, one of the most spectacular eruption was performed by Johnson and Graziano,14 who created a remote controlled four-way simultaneous mentos eruption. Researchers who are interested in special effects techniques and remote insertion methods should read the details concerning these methods. And in an accidental discovery certain to create numerous follow-up studies, Jagielski and Hedberg created and launched a Mentos Rocket.15

In summary, despite over twenty published articles in the first two Journals, two of the fundamental theories regarding this eruption have yet to be investigated, including: 1. Is gum Arabic the key group of substances in the Mentos Eruption, or is that simply a myth? 2. What is up with the nucleation sites? Many experiments have indicated that the surface character of a mentos is critical to the height of an eruption, but the actual surface shape (topology) has never been photographed, either alone or during the eruption, although time release photography has come close. This key theory needs to be tested. As it stands now, Guilford High School is, to our knowledge, the only place where the Mentos Eruption is being carefully studied leading to published results. That being the case, there is every reason to believe that significant discoveries will continue to be made in this wide open field of research. 1. Guilford Journal of Chemistry, Volume 1 (2007), H. Brielmann, editor. Available online at http://chemistryadventure.com/Documents/guilford%20journal%20of%20chemistry%20volume%201.pd f 2. For an informative historical account of the Mentos Eruption, Speve Spangler‟s website is recommended: http://www.stevespanglerscience.com/experiment/00000109. Note that the original Letterman Show Mentos Eruption may be viewed on the internet at http://www.chem.uic.edu/marek/letterman0/video/mentos.htm. For accounts of Mentos-like eruptions dating back to the 1980‟s, see: Marek at http://www.rimmkaufman.com/rkgblog/2007/12/21/stevespangler/. 3. The mythbusters investigation of the mentos eruption may be found at http://dsc.discovery.com/videos/mythbusters-diet-coke-and-mentos.html. A fairly lame christmas themed investigation called “Merry Blastmus can be viewed at http://dsc.discovery.com/videos/mythbusters-merry-blastmus.html. And an ultra-slow motion mythbusters view of the eruption is at http://dsc.discovery.com/videos/time-warp-soda-fountain.html . 4. Rachel Cutler and Emma Smith, Guilford Journal of Chemistry, Volume 1, Pages 6-12 (2007). 5. For example, see Steffi Marsh and Taylor Smith, Guilford Journal of Chemistry, Volume 1, Pages 1316 (2007). 6. Although details are unavailable, see Paul Mulligan and Jared Searles, Guilford Journal of Chemistry, Volume 1, Page 12 (2007) 7. Sam Taylor and Will Schaffer, Guilford Journal of Chemistry, Volume 2, Page 38 (2008). 8. Allison Federici and Jess LaChance, Guilford Journal of Chemistry, Volume 2, Pages 15-16 (2008). 9. Angelise Musterer and Lindsay Ruotolo, Guilford Journal of Chemistry, Volume 2, Pages 12-14 (2008). 5


10. Kaitlyn Earles and Megan Graham, Guilford Journal of Chemistry, Volume 2, Pages 21-22 (2008). 11. Emilies Kipness and Ring, Guilford Journal of Chemistry, Volume 2, Page 38 (2008). 12. Nick Hill and Kyle Gaboury, Guilford Journal of Chemistry, Volume 2, Page 38 (2008). 13. Kelsey Robins and Laura Turcio, Guilford Journal of Chemistry, Volume 2, Page 38 (2008). 14. Ryan Johnson and Will Graziano, Guilford Journal of Chemistry, Volume 2, Pages 9-11 (2008). 15. Alex Jagielski and Eric Hedberg, Guilford Journal of Chemistry, Volume 2, Page 38 (2008).

6


Introduction to the first Issue This first issue of the Guilford Journal of Chemistry includes groundbreaking discoveries in the field of Mentos Eruptions. In its simplest form, the Mentos eruption involves dropping Mentos candy into a soda (usually diet coke), resulting in a foamy eruption, which can often be several meters in height. The first widely viewed Mentos eruption occurred on September 14, 1999 on the David Letterman show,1 though earlier eruptions using other candies (with less spectacular results) had been used primarily by teachers dating back to the 1980â€&#x;s.2 In terms of scientiic research this field is still in its infancy, sinc e this area of research has almost no peer-reviewed published research results,3 although numerous videos documenting riveting eruptions are available on the internet,4 and on commercial television.5 Several unverified explanations have been offered to explain the eruption6, usually focusing on the physical shape of the mint (so-called nucleation sites), or on the various ingredients in the mint, particularly gum arabic. It is important to note that none of these hypotheses have been scientifically verified. This journal represents the first attempts to scientifically investigate the mentos eruption. Several previously unrepoted discoveries are documented in this journal. Perhaps the most fascinating discovery was made by Cutler and Smith.7 This featured papers reveals that that the height of a mentos eruption can be dramatically increased by freezing a mentos candy prior to dropping it in the soda. Coupled with the predictable observation that heating a mentos candy will increase the height of an eruption, this creates a bizarre result: the the height of a mentos eruption is relatively high when the candy is cold, low when the candy is at room temperature, and then high again when the candy is warm or hot. This discovery could in principle create world-record eruption heights (the current record is 29.2 feet). Another serendiptous discovery was made by Marsh and Moalli.8 While attempting to create a timedelayed Mentos eruption, they chanced upon a method for sustaining an eruption for over 40 seconds. More importantly, their graph suggests that this method could be applied to create eruptions that occur for several minutes in theory, though there were some occasional reproducibility issues that will have to be addressed. Several of these papers are design-based, in which an eruption of a certain type is desired and executed. Methods for creating several spectacular effects are published in this issue. Those interested in creating a unique misting effect should read the work of Necklas and Wall.9 Those looking for both an extremely high as well as a sustained eruption should turn to the work of Davis and Dillon.10 Space does not permit the higlighting of all articles. However, all of these investigations created spectacular eruptions and we hope you enjoy reading about them Dr. H. Brielmann Editor in Chief 7


The Guilford Journal of Chemistry

References: 1. For an informative historical account of the Mentos Eruption, Speve Spanglers website is recommended: (http://www.stevespanglerscience.com/experiment/00000109. Note that the original Letterman Show Mentos Eruption may be viewed on the internet at http://www.chem.uic.edu/marek/letterman0/video/mentos.htm. 2. For accounts of Mentos-like eruptions dating back to the 1980â€&#x;s, see: Marek http://www.rimmkaufman.com/rkgblog/2007/12/21/steve-spangler/

3. For example, the search term Mentos gives no results currently from popular scientific search engines currently (2008), including PubMed or Google Scholar. Online material is available from the Royal Society of Chemistry (http://www.rsc.org/education/teachers/learnnet/pdf/learnnet/classicdemos/mentosexplosion.pdf), but no experiments were performed in either case to test their ideas. For interesting reading on the explosion of popular online science sources, see http://www.rsc.org/chemistryworld/Issues/2007/December/SurfingWeb20.asp . 4. In addition to YouTube, other websites have arrived that are dedicated to the mentos eruption. Of particular mention is geysertube (http://www.geysertube.com/blog/ UPDATE 2009: dead site), where one can view the Mentos Eruption in ultra-slow motion. 5. For example, on the popular television series Mythbusters (http://dsc.discovery.com/fansites/mythbusters/mythbusters.html). 6. Most literature on the Mentos Eruption cites the website of Fred Senese (http://antoine.frostburg.edu/chem/senese/101/consumer/faq/mentos.shtml), however there are no experiments performed or cited in support of these hypotheses.

7. Rachel Cutler and Emma Smith, Guilford Journal of Chemistry, Volume 1, Pages 6-12 (2007). 8. Steffi Marsh and Taylor Smith, Guilford Journal of Chemistry, Volume 1, Pages 13-16 (2007). 9. Gabriella Necklas and Kiersten Wall, Guilford Journal of Chemistry, Volume 1, Pages 33-35 (2007). 10. Aaron Davis and Travis Dillon, Guilford Journal of Chemistry, Volume 1, Pages 17-18 (2007).

8


The First Four-Way Remote-Control Release Mechanism for Diet Coke and Mentos Eruptions by Ryan Johnson and Will Graziano

Ever since the discovery of the Diet Coke and Mentos phenomenon, numerous experiments have been done for the betterment of science, for "cool factor," or simply for fun. However, we have for a long time been barred from reaching our true potential in the extremity of these experiments for fear of being covered in sticky, fizzy Diet Coke. Many have wondered, "How can we release the Mentos into the Coke without getting soaked? And how can we do multiple releases simultaneously without the need for multiple people to do it manually?" My colleague, Will, and I wondered the very same thing; we wanted to perform a spectacular four-way simultaneous eruption from a safe distance using a remote control device - and after much brainstorming and several different plans, we found a way to do just that. The Experiment Using a table which was approximately .75 meters by 1 meter as our surface, we fixed the engine of a remote control car on its side to the middle, and built a special four-way hook device to hold (and release) fishing lines which would be connected to the Mentos. Four posts of approximately 30 centimeters were fixed to the corners of the table, one in each corner, to which one bottle of Diet Coke each was also secured. With four lengths of fishing line, three Mentos each, and one paper clip each, we devised a line which would hold the Mentos up inside the bottle until the device was activated. When activated, the remote control car engine at the center and the hook device attached to it would spin, unhooking all four lines at the same time and thereby releasing the Mentos into the bottles. Summary of Findings The device, crude though it was, worked just about perfectly - however, we found that the remote control car we used for the experiment was faulty and did not run immediately, so in future experiments a more reliable engine should be used. The result was a spectacular quadruple geyser of Diet Coke spraying into the air, and much applause from our classmates. Conclusions 9


With the success of the device, it is our firm belief that we have revolutionized the Diet Coke and Mentos phenomenon - with added improvements from our successors, it will now be possible to pull off much messier and more impressive displays using the Diet Coke and Mentos combination. Such suggested experiments could be a simultaneous eruption of more than four bottles, or perhaps a wheel device that uses the force of the erupting Coke to spin. The possibilities have suddenly expanded tenfold with this amazing discovery. Experimental Procedure Materials: Supplies to build a table approximately 3 square feet, or such a table pre-built, with a 12-inch post secured to each corner. 4x 2-liter bottles of diet Coke 1x box of Mentos (approx. 24 Mentos) - 12 are needed for the experiment 1x spool of fishing line - any pull strength 1x remote control car -shell removed 1x roll of duct tape - use more as needed 1x board that will fit underneath the remote control car and raise it slightly off the table. 8x paper clips - use more as needed 2x drill bits - one 1/8" and one 2mm wide 4x additional bottle caps for 2-liter Coke bottles - for drilling the holes Safety goggles Procedure: Remote Control Device: 1. Secure the engine to the table such that the wheel is facing up and is as close to the dead center of the table as possible, and that the smaller board is keeping the bottom wheel off the table. Secure tightly with duct tape. 2. Unbend the largest bend of each of four paper clips so that it forms an L-shaped hook with the rest of the paper clip untouched. 3. Secure the paper clips together using duct tape so that it makes a pinwheel-shaped device. 4. Tape this hook device onto the wheel so that the tip of the hooks are all facing in the opposite direction that the wheel is turning. Mentos Strings: 1. Drill one hole in each of the 12 Mentos you will use, using the 2mm drill bit 2. Cut four pieces of fishing line (string), each long enough to cover the distance between the bottle cap and the hook plus about five inches. 3. tie a paper clip onto one end end of each piece of string, conserving as much length as possible. 4. String three Mentos onto each line - the paper clip tied onto the end should prevent the Mentos from slipping off. 5. Tie a small knot on the other end of each string - should be slightly wider than the hooks. 6. Cut extra slack off. 7. Drill one hole in the center of each of the four extra bottle caps using the 1/8" drill bit. 8. String one bottle cap onto each of the lines so that when screwed onto the bottle the Mentos will be inside the bottle. Assembling the whole contraption: 1. Tape one Coke bottle to each post, facing towards the center of the table. 2. Unscrew the bottle cap and screw on the bottle caps with the lines through them. (Note: Recommended this part of the assembly be done after transporting the whole device to the appropriate site for the eruption to reduce the risk of accidental release of the Mentos)

10


3. Loop the knots on the other end of the lines onto each of the hooks - there should be no slack between the hook and the bottle, and the mentos should be hanging as high inside the bottle as possible. The lines should be without slack, but not tight. The eruption: Be sure that the whole device is relocated to an appropriate spot for the eruption - it will be very messy, so a flat surface outdoors would be ideal. Hit "forward" on the remote (having already made sure everything is turned on) and the wheel will spin, unhooking the lines and dropping the Mentos into the Coke bottles simultaneously. Suggestions for later repeats - Improve the reliability of the device: Use a higher quality remote control car engine; use safer hooks which will not release until the wheel spins; use more reliable materials to secure the engine and bottles to the table rather than duct tape and nails. - Improve versatility of the device: With a little ingenuity, this concept can be reconfigured for many different types of experiments. Also, contrive a means of making the engine waterproof for reusability. - Devise ever more fantastic and impressive displays of the powers of Diet Coke and Mentos.

11


Diet Pepsi –Not Diet Coke – Produces Highest Results in Mentos Eruption When Compared to Other Diet Carbonated Drinks By Angelise Musterer & Lindsay Ruotolo Summary: For our experiment, we took four different types of soda to see the effects of mentos on some carbonated drinks. The drinks we used were Diet Coke (as the control), Diet Pepsi, Fresca, and Sprite Zero. By doing this, we were able to see if this was just a reaction that would occur with Diet Coke and mentos or mentos and the other carbonated drinks too. In the end, Diet Pepsi reached the highest measurement of 94 cm, Sprite Zero came next with a close second of 79 cm, Diet Coke came in third with a height of 43 cm, and Fresca came in last with 15.24 cm. Introduction: When the mentos eruption was tested by the Mythbusters, they concluded that the reason the reaction took place was due to the potassium benzoate, aspartame, caffeine, and CO2 gas in the Diet Coke and the gum Arabic and gelatin in the mentos (http://en.wikipedia.org/wiki/Mentos_eruption the results concluded by the Mythbusters‟ experiment). We tested this theory by using different types of soda, and we noticed that in our trials, the Diet Coke did not have one of the biggest eruptions. The world record has been set for the highest eruption using Diet Coke, but we believe that if someone tried other kinds of soda, there might be a new world record. Experimental: 1. Get 2 Litters bottles of 4 different types of soda (Diet Coke, Diet Pepsi, Fresca, Sprite Zero) 2. Get a couple packs of mint mentos 3. Place a measuring tape against a wall, preferably outside!! 4. Set a bottle on a flat ground in front of the tape 5. Get a small plastic tube about the same diameter as the opening of the bottle and insert 3 mentos; place a piece of paper under tube so that mentos don‟t fall out 6. Unscrew the cap and put on safety goggles 7. On a count of three pour in the mentos or slide the paper out and step back 8. Watch for the height of the eruption and record how high it goes (its helpful if at the peak of the eruption you take a picture to more accurately know/see the height) 9. Repeat steps 4-8 twice (once for each trial) with each type of soda 10. record all data in a table

Conclusion: In our experiment, we found that the soda that actually worked the best was the Diet Pepsi. This may have something to do with the ingredients in the soda or just may have been experimental error. Since we did only one test for each type of soda due to lack of supplies, we can‟t be certain that our results were accurate. In another experiment, in which people used different types of soda and Diet 12


Coke as a control, they did two trials. It was found that there was a drastic difference between the first and second trial (The Guilford Journal of Chemistry, results by Ethan Shore and Zack Brown). Maybe if we did two trails, we would have also seen an increase or even a decrease as they did; finding that our first trial was flawed. Another experimental error could have been that for our first trial using the Diet Coke and Sprite Zero, we used a piece of string to drop in the mentos and in the last two sodas, we dropped them in by hand. This was shown through the fist two sodas, which were the ones that went the shortest height. Other than these errors and the unusual mistakes in measurement and uncontrollable variables, such as the wind or the amount of carbonation that was left in the bottle before we could do the eruption, our experiment went very well. We believe our results are still accurate because the difference between the two sodasâ€&#x; data (diet Coke and Diet Sprite), it would be hard to justify it as just an experimental error. According to out results, if you were trying a mentos eruption to see how high it could go, it would be best to use Diet Pepsi instead of Diet Coke. References: 1. For background on the mentos eruption, Wikipedia website was very useful and also provided other links that were helpful as well: (http://www.wikipedia.com/). 2. The very popular t.v. show Mythbusters added to our research and ideas: (http://www.dsc.discovery.com/fantacies/mythbusters/mythbusters.html). 3. Dr. H. Brielmann. The Guilford Journal of Chemistry, Volume 1, pages 4-5 (2008). 4. Ethan Shore and Zack Brown. The Guilford Journal of Chemistry. Volume 1, pages 15-16 (2008).

Diet Pepsi Highest Results in Mentos Eruption When Compared to Other Carbonated Drinks

40

35

30

25

Height(inches) 20 37 31

15

10 17 5 6 0 Fresca

Diet Coke

Sprite Zero

Diet Pepsi

Type of Soda

13


different flavors resulted in different eruptions. We found that the flavor which had the biggest reaction was cinnamon, with an average height of 10 cm; followed by mint and fruit which had the same reaction, with an eruption height of 8.5; sugar free was second to last with a height of 4.5 and then sour had the smallest eruption with a height of 3.5. We also noted that the sugar free mentos had more foam flow out of the bottle whereas the fruit reacted quickly but left a large amount of foam inside of the soda bottle. The sour mentos was much different as its eruption lasted a long time, with foam and larger bubbles. This leaves cinnamon, which was the quickest reaction and foamiest. 1. Guilford Journal of Chemistry, Vol. One, Page 5. (2008) www.rimmkaufman/rkgblog/2007/12/21/steve-spangler) 2. Guilford Journal of Chemistry, Vol. One, Page 17-18. (2008) 3. Guilford Journal of Chemistry, Vol. One, Page 6-12. (2008) 4. “Fruity vs. Minty� Guilford Journal of Chemistry, Vol. One, Page 2. (2008)

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Cinnamon Mentos Erupt 20% Higher than Mint Mentos By Allison Federici and Jess LaChance

The Mentos and Diet Coke is a very well known experiment that can be dated way back to the 1980’s.1 This experiment deals with dropping any number of mentos into a carbonated soda (usually Diet Coke). When the chemical reaction occurs, a huge eruption of foam shoots out of the top of the bottle. Starting this experiment we knew that mint mentos were the classic or most well known flavor to make the biggest explosion. When people tested different variables they always used either Mint mentos or Diet Coke as their control. 2,3 Previously, some one had tested fruit and minty mentos, but details are not available.4 Since it wasn’t in their title, we assumed that they had not tested more than just fruit and mint mentos. As far as we knew, we would be the first to test five different flavors and their effect on eruption height in Diet Coke. For our experiment we tested the eruption height of Diet Coke depending on the different flavors of mentos. We experimented with regular mint, sugar-free mint, sour, fruit and cinnamon in 8 oz. bottles of Diet Coke. We found the sour and the sugar-free mentos had little to no eruption and the cinnamon mentos erupted only a few centimeters higher than the regular mint mentos. The fruit mentos erupted just as high as the regular mint ones. We were trying to find out if the mint mentos were the best to use, to get the highest eruption. 1. Gather materials, such as 10 8 oz. bottles of diet coke; sugar free, cinnamon, fruit, mint, and sour mentos; plastic tube; toothpick; meter stick and safety goggles 2. Place one bottle of diet coke into sink 3. Fill the plastic tube with 4 sugar free mentos 4. Secure the mentos with toothpick 5. Put on safety goggles 6. Place the tube into top of bottle 15


7. Have meter stick ready next to bottle to record height 8. Pull toothpick out of tube, releasing mentos into soda; quickly pull tube away 9. Record height 10. Repeat steps 2-8 using cinnamon, fruit, mint and sour mentos 11. Repeat steps 2-8 using all 5 mentos flavors for second trials

The Effects of Different Flavored Mentos 12

10

Height (cm)

8

1 2 avg.

6

4

2

0 Mint

Sugar Free

Fruit

Sour

Cinna.

Flavors

The results of our mentos lab were very conclusive. It was shown that, indeed, the different flavors resulted in different eruptions. We found that the flavor which had the biggest reaction was cinnamon, with an average height of 10 cm; followed by mint and fruit which had the same reaction, with an eruption height of 8.5; sugar free was second to last with a height of 4.5 and then sour had the smallest eruption with a height of 3.5. We also noted that the sugar free mentos had more foam flow out of the bottle whereas the fruit reacted quickly but left a large amount of foam inside of the soda bottle. The sour mentos was much different as its eruption lasted a long time, with foam and larger bubbles. This leaves cinnamon, which was the quickest reaction and foamiest. 5. Guilford Journal of Chemistry, Vol. One, Page 5. (2008) www.rimmkaufman/rkgblog/2007/12/21/steve-spangler) 6. Guilford Journal of Chemistry, Vol. One, Page 17-18. (2008) 7. Guilford Journal of Chemistry, Vol. One, Page 6-12. (2008) 8. “Fruity vs. Minty� Guilford Journal of Chemistry, Vol. One, Page 2. (2008) 16


Six Meter Coke and Mentos Eruption Achieved By Heating The Bottle By Mary Melillo and Artem Guryanov

Summary This experiment tested whether the temperature of a bottle of the Diet Coke would affect the height of a Mentos eruption. The first bottle was unheated and acted as our control for the experiment, while the second and third bottles were heated up to different temperatures. Our results made it clear that the higher the temperature rose inside the bottle, the height of the eruption rose in height as well. Introduction Mentos eruptions have been well-known since September 14, 1999, where one was performed on the Dave Letterman show, 1 but tests on effects of temperatures on the bottles before adding the Mentos are not very common. One experiment on the topic claimed that the reaction rate appears to double every ten degree in Celsius that you heat the Diet Coke, and that for every ten degrees the bottle is cooled, the reaction power is cut in half.2 The results of a recent experiment support the idea that warmer temperatures will result in greater eruption height.3 Our experiment tests that theory by heating up the soda to various temperatures and shooting it off, measuring the height of the fizz. Procedure 1. Gather materials: 3 2-liter bottles of soda, 15 mint Mentos (more preferred because some might break apart), string (skinnier is better), a drill, a sink that can produce hot water, thermometer (we used Celsius, but a Kelvin thermometer would eliminate the need for conversions later on), a fourth bottle cap, clamps/pliers, and some sort of measuring device (in meters) 2. Take the drill, pliers/clamps, Mentos, and the fourth bottle cap.

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3. Take the pliers and secure the Mentos to them one by one and drill a hole through them, the pliers are there for your hand‟s safety in case you slip and accidentally try and drill your own hand. 4. Drill a hole through the fourth bottle cap as well. 5. Tie a piece of string around the first Mentos and then slide four more on the same string (the length of the string can vary, for best results try a 2-5 inch string length). 6. Take the Mentos on the string, the bottle of soda, the measuring device, the bottle cap, and the thermometer outside. 7. Open the bottle, making sure none of the fizz spills out and slide in the thermometer and record the temperature. That is your control. (In order to best match our results, the control should be about 294.15 K, or 21°C) 8. Slide out the thermometer and slip the string through the hole in the bottle, making sure the five Mentos are on the inside of the cap and screw it on the bottle. 9. Make a countdown and release the string, causing the Mentos to fall into the soda and back away. 10. Watch the explosion and record the height in meters. 11. Repeat steps 3-10 for a second bottle, except this time fill a tub with hot water and rest the bottle in the tub until it reaches 298.15 K (25°C). 12. Repeat steps 3-11, this time for a second bottle and this time heating up the soda to 301.65 K (28.5°C) Note: Be careful when opening the bottles, especially the warm ones, as they will be pressurized when you open them. If you recorded your temperature in Celsius, you may want to convert it to Kelvin (as we did), which is the SI unit of temperature.

Results 18


The control (unheated) bottle of diet coke, which was 294 K resulted in an approximately 4-meter-high explosion. The second bottle, heated to 298 K, resulted in a notably higher explosion, reaching 5.5 meters. Finally, the warmest bottle – at 301 K – created an explosion about 6 meters high. It should be noted that we were not able to run multiple trials and so our data may not prove consisted over multiple tests.

Conclusions Our results clearly support the theory that using warmer Diet Coke will result in a higher Mentos eruption. Each time we raised the temperature of the soda, the result was a taller eruption, with our warmest bottle‟s eruption reaching six meters! This can certainly be taken as proof that raising the temperature of Diet Coke affects the eruption size. However, a follow-up experiment where multiple trials are used would be a good idea to test the consistency of this fact. Other follow-up experiments may include heating the soda up to even warmer temperatures, or testing both heating and cooling the soda to compare the effects. References 1. A video of this eruption can be found at: http://www.chem.uic.edu/marek/letterman0/video/mentos.htm 2. Information found from Justin Husted, Guilford Journal of Chemistry, Volume one, Pages 19-20 (2008), where the information is cited from “Username: „Labmonkey‟ Yahooanswers.com January 10th, 2008.” 3. Justin Husted,

Guilford Journal of Chemistry, Volume one, Pages 19-20

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Names: Mike Amento, Scott Leone Period: 2 Time Delayed Diet Coke and Mentos Eruption By Mike Amento and Scott Leone Introduction: We report here the first time delayed Mentos eruption. This practical device allows the scientist performing this experiment to get clear out of the way of the eruption, offering practical and safety advantage . Experiment: This technique is based on lighting a fuse to run up to the top of the Coke bottle. It was brilliant. The fuse was a long piece of string tightly holding the mentos at the top of the bottle. When we lit the fuse, it took about 10 seconds to burn through the string and break it apart. As the fuse broke, its tight grip on the mentos gave way and they were released into the Coke, thus causing the delayed reaction of the experiment. We were delighted to discover as well that the time delay had no effect on the size of the fountain we were able to form. Each fountain was consistently 6-8 feet tall, and displaced the same amount of Coke. Conclusion: In this experiment we used a flame as a remote device for a mentos eruption. The idea was very successful, and we were able to create a delayed mentos eruption. Our idea was that we use a piece of string as a fuse. We tied the string to the top of the coke bottle and the other end was taped down to the table. We had the mentos hanging off the end of the string, which meant that when the string dropped the mentos would fall into the coke. Then it was as simple as just lighting a candle and placing it close enough to the string so that it would burn it. We came out with times of 15 seconds, 8 seconds, and 10 seconds. This gives us an average time of 11 seconds. It may seem short but it is actually a very good amount of time to get far enough away from the eruption so that you won‟t get soda on you. This experiment was a success. Really the only things that we could have changed were the kind of string used, for more variability. References: 1. We got this great idea from Paul Mulligan and Jared Searles‟ experiment. They also tried to create a remote for a mentos eruption. “Creation of a remote controlled Mentos Eruption” 2. www.Stevespangler.com

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Title: Volume Analysis of a Mentos Eruption 3. A one paragraph summary of your experiment and results. By Kaitlyn Earles and Megan Graham

Summary: A quantitative volume-based (rather than height-based) measurement technique was developed to assay Mentos eruptions. To accomplish this we measured each explosion by soda displacement and how much was left in the coke bottle and we found the percentage of how much exploded. We were excited to do this experiment because no one has ever tested soda displacement. This technique can be used to measure the intensity of a Mentos eruption independent of eruption height or nozzle size. Introduction Although there have been many experiments that measure how high a mentos explosion is, there is none that is measured by soda displacement. Our observations show how big the explosion actually is by measuring the soda displacement. We tested different volumes and the volumes effect on the explosion. The bigger soda displacement the bigger the explosion, which volume do you think will have the biggest?

Experimental 1. Put on safety goggles 2. Drill one hole in 3 mentos 3. String the mentos and tie a knot at the end of the string 4. Unscrew Coke bottle and very quickly drop mentos inside 5. Measure the volume thatâ€&#x;s left inside the coke bottle 6. Find the percentage that is still inside and that has left the bottle. 7. Record all data in a table. 8. Clean up all materials

(use additional space if necessary)

21


Results

Volume

Trial 1

Trial 2

Trial 3

Average

12 fl oz 20 fl oz 67.6 fl oz

157 ml 243 ml 800 ml

180ml 267ml 900ml

164 ml 242ml 850ml

167 ml 250ml 850ml

% in bottle 47.3% 42.4% 42.5%

% out of bottle 52.7% 57.6% 57.5%

Most bottles ended up with half the amount it started with. Each explosion needed half the amount of the bottle.

Conclusions In wrapping up the experiment we concluded that the volume does not have an effect on the mentos explosion because as our results showed each bottle had around 50% of soda displacement which means each explosion was about half the size the volume. We were a little disappointed that the volume didnâ€&#x;t have a big impact on the explosion but we are excited to know that no matter how big the volume the explosion will be the same with the same amount of mentos.

(use additional space if necessary)

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Names: Holly Aery and Adam Sierzputowski

Period: 2

Eruptions Caused by Mentos Increase in Height with 3. A one paragraph summary of your experiment and results. Smaller Nozzle Sizes By Holly Aery and Adam Sierzputowski

Summary: We wanted to see how different nozzle sizes of diet coke bottles affect the size of Mentos eruptions. We drilled different sized holes in the caps of bottles creating nozzle sizes ranging from .5 cm up to 4 cm. After dropping in 4 mentos, we were able to see just what kind of eruption the nozzle sizes could create, which was a rather large one of 153 cm, considering we used 20 oz soda bottles.

Introduction: People have previously tried putting mentos in soda just to see it erupt, however it is also very fascinating to learn about why this reaction occurs. According to several untested web sources,1 in the soda, the water is tightly linked around the carbon dioxide which creates a strong surface tension that resists the bubbles from forming and expanding. Then, when the mentos are dropped in the soda, the surface tension is broken from the gelatin and gum arabic in the mentos. These ingredients disrupt the way the water was linked to the carbon dioxide, making it easier for the carbon dioxide to expand, and create a large eruption. There have also been previous attempts by scientists at Guilford High School concerning the same nozzle-size experiments, and similar results were found. Aaron Davis and Travis Dillon found out that the smaller nozzlesizes create higher explosions, which is the same conclusion we had.2 We had also hypothesized that the smallest nozzle would create the highest explosion because it creates more pressure. After all, an explosion is a violent bursting as a result of internal pressure. 3 Therefore, the more pressure there is, the higher the explosion will be able to go.

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Experimental Procedure: The goal of this experiment was to alter eruption height by changing the nozzle sizes of the 20 oz diet coke bottles. At first, we only used 3 mentos but it did not create a large enough explosion so we increased the amount to 4 mentos and tied them on a string to drop them properly. However, we made sure not to include that test trial in our final results. Our positive control was the un-tampered regular sized bottle cap (3.2 cm). It created an explosion that we could compare our other results to because that is the cap size used in regular diet coke and mentos explosions. We did manage to find out, though, that the smallest nozzle size created the largest explosion just as we expected. 1. Gather Materials. - 3 20oz. bottles of diet coke with cap sizes of 3.2 cm - 1 20 oz bottle of vitamin water (empty) with a cap size of 4 cm - 12 mint flavored mentos - String (which you will tie the mentos to) - Drill (to put holes in the mentos/bottle caps - Meter stick 2. Drill a .5 cm hole into each of the mentos. 3. Fill the vitamin water bottle (with a cap size of 4 cm) with diet coke. 4. Drill a .5 cm hole into the cap of one diet coke bottles. 5. Drill a 1 cm hole into the cap of another diet coke bottle 6. String 4 mentos onto a piece of string and tie a knot at the bottom to ensure them not to fall off. 7. Go outside (so as to not make a mess) while taking the diet coke bottle with a 3.2 cm opening (the control) and quickly drop the string of mentos into the bottle. 8. Get about 3 feet away from the explosion and observe and record the height of the explosion. 9. Repeat steps 5-8 using the diet coke with the .5cm hole in the cap. Drop the mentos by holding the mentos string above the liquid through the hole and then dropping the string to create the explosion. 10. Repeat step 9 using the diet coke with the 1 cm hole. 11. Repeat steps 5-8 using the vitamin water bottle (with 4 cm cap) filled with coke 12. Now that all the experiments have been completed, clean up and recycle all soda bottles.

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Results The results we found during the experiment were that the smaller the hole, the higher the soda sprayed. The highest spray came from the bottle with the smallest hole. The hole was .5 cm. around and the soda sprayed 153 cm. high. The largest hole got the least height. It was 4 cm. around and barley got 1 cm. high. Our control went the third highest with an open cap 3.2 cm. around. The control went about 30 cm. high. A 1 cm. hole went 60 cm. high.

160 140 120

Control Open Top .5 cm

100 80 60

1 cm

40 4 cm

20 0 open .5 cm 1 cm top

4 cm

25


Conclusions Due to the data we received we can infer that the smaller the opening the higher the soda will spray and the larger the opening the lower the soda will spray. We found that a hole that was .5 cm. around sprayed about 153 cm. high. We also found that the larger the hole was the least height it got. A hole of 4 cm. (the largest hole) barely got 1 cm. high. From our data we can conclude that the smaller the spray hole the higher the soda will spray. But several issues could have interfered with these results. Number one, we had to pour soda into one of the bottles. This could have made the soda go flat. Two, the bottles could have been shaken causing the soda to become flat. Three, the mentos could have fallen off of the string before the experiment was ready to begin causing an early spray. Some of these miscalculations could have messed up the data we received. To make this experiment more valid we could have done more trials. In a follow-up experiment you should add more trials. Also you have smaller hole sizes to see if the results are valid enough to conclude.

(use additional space if necessary)

26


Title: Comparing Mentos Eruptions of Diet Coke as opposed to JOLT energy supplement By Dylan and Trevor Summary: We decided to compare the Mentos eruption using diet coke with that of JOLT energy supplement. Unfortunately, The reaction using JOLT energy supplement failed to produce a reaction. However, we discovered that the key ingredients in Diet Soda that causes the violent reaction with mentos are Potassium Benzoate and Aspartame. Introduction There is no information prior to our experimentation that could possibly confirm or deny the possible allegations that “liquid energy supplements” do or do not cause a “reaction” with.mentos. The reason that We decided to do our test using liquid energy supplements was by reasoning that synthetic ingredients in the soda cause the reaction. This was found to bot be the case and JOLT energy supplement failed to produce a reaction. However, it led to us to take a closer look at our ingredients, and to discover that Potassium Benzoate and Aspartame are the causes of the reaction with mentos. Experimental 1. Gather Materials (JOLT Energy supplement, copious amounts of Mentos.) 2. Set up controlled environment 3. Don Goggles (no other protective gear required) 4. Create mentos dropping apparatus: mold paper tube to slightly larger diameter to that of the mentos roll, use tape (any kind) to keep in place. Run a toothpick through the extreme on one end, across the diameter. Drop mentos in other side of tube, until full. 5. Suspend full mentos dropping apparatus above can of JOLT, then open can of JOLT and release mentos (remove toothpick from the bottom end of apparatus) 6. STEP BACK. 7. Record data, clean up materials. Results 1 inch eruption Conclusions Our conclusion is that Energy drinks are not the best reactive substance, nowhere near diet coke’s potency. To achieve maximum effect, use as much diet coke as possible, with as many mentos as possible, as unfortunately energy drinks simply cannot produce the desired reaction. There may have been some room for error in the preparation state, perhaps they were shaken up at one point or another, unbeknownst to us, causing them to loose carbonation. If we could do it again, we would definitely use diet coke instead of energy drinks, to achieve maximum explosion. References 1. www.youtube.com/watch?v=IZDFn4VFe9s&feature=related

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HOW THE AMOUNT OF MENTOS AFFECTS THE HEIGHT OF THE ERUPTION Matt Feldman and Alex Monte Introduction: Over the years several scientists have used diet coke and mentos to make a large reaction with only a liter of coke. Many experiments have been conducted to see what factors really do go into making the eruption actually go. Many people have also attempted to break the world record of 29.2 feet in many different forms. Others tried experimenting with different cap sizes, amount of mentos, pressure added to the reaction, and even temperature. We wanted to experiment using a large amount of mentos to get a very high reaction to see if it really had an affect on the height. It requires a large amount of mint mentos, and a lot of confidence in what you are doing. Based on a slip-up by Mr. Monte, future testers are advised to remember to get out of the way after the mentos have been put into the liter of diet coke! Summary: While coming up with this experiment, we had one goal to accomplish when making this test; to break the 29.2 foot record set by previous scientists. We made a careful plan to try and produce the best results and even considered several factors to get the highest reaction. This task was easier said than done, and ended up requiring a lot more mentos to get the record. In the end, we used 5, 10, and 40 mentos as our test, and they each produced a different height. Materials: Regular Mint Mentos (Approximately 9 packages of 14) 3 Liters of Diet Coke Several sheets of 9” X 8” Sheets of Paper Science beakers (Able to accommodate large amounts of mentos) Safety Goggles Tape Measure A Bin to Catch the Eruption if you are Experimenting Inside Safety Rules *Always wear your safety goggles *Be careful with the glass beakers *Do not mess around while conducting the experiment * No horseplay Procedure: 1 Gather materials required to conduct the experiment 2. Take a piece of 9” X 8” piece of paper and roll it into a funnel. Make sure the mentos can get through the smaller end of the funnel, and can accommodate the large amounts of mentos that are going to slide down the funnel. 3. Test the funnel numerous times by putting about fifteen mentos in and out of the funnel so you know the funnel works. 4. Put on Your Safety Goggles

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5. Make sure you are in a safe environment and are in an area where you can measure the height easily. You might want to have someone record a video so you get the exact height. Then take the liter of diet coke, put it in a secure position so it doesn‟t fall down and quickly take off the cap. 6. Then quickly place the funnel over the liter of diet coke so the small hole is going into the opening of the bottle. Then pour the beaker of 5 mentos into the wide end of the funnel. 7. Remove the funnel to get your reaction and back up as much as you can so you don‟t get sprayed. 8. Repeat steps 4-6 only this time use 10 and 40 mentos for your trials. Don‟t forget to write your results in your data table. 9. Make sure to pour the mentos in very quickly or else the reaction will occur too fast and you won‟t have an accurate eruption height.

Height of Mentos

Height (Meters)

3.5 3 2.5 2 1.5 1 0.5 0 5

10

40

Number of Mentos This graph indicates that the more Mentos entered into the diet coke, the higher the eruption. When only 5 Mentos were entered the eruption was only 1.02 meters, when 10 were placed in 1.09 meters was the height, and when 40 was put in there was a drastic change and the eruption was 3.5 meters. CONCLUSION After we finished our three trials in the experiment, we determined that the amount of mentos does affect the height of the eruption. The more mentos we put into the bottle, the higher eruption we got. Although we realized that our goal of breaking the record of 29.2 feet was out of reach, we still had fun and realized that trying to get 40 mentos into one liter of coke, and get accurate results is easier said than done. While conducting this experiment, we came up with several flaws that affected the outcome of the experiment. First, while putting the mentos into the liter of coke, we found that it was hard to get every single mentoe into the liter before the reaction actually occurred. A practice test that we conducted, which ended up producing no results at all, showed us that we had to come up with a really good way to get the mentos in quickly and affectively. In the end of that practice test, our method did 30


not work because the funnel slid away, causing no mentos to go in. Therefore we had to result to using a funnel where the small end almost went into the liter. When doing the 40 mentoe trial we poured the beaker of mentos into the funnel which allowed the mentos to slide into the liter. However, the reaction occurred too quickly resulting in the infamous splash on me. This produced flawed results because that could mean that the soda was only reacting to the mentos that made it into the bottle, not all forty. On the other hand, the reaction could have gone higher if I didn‟t get in the way. Another thing that we could have changed while conducting the experiment was adding in more trials. We only conducted 1 five, ten, and forty mentoe test, mainly because that was all the supplies that we had. However, if a flaw occurred, like so in the forty mentoe test, we might not get the results we were looking for compared to an average height with 3 trials for each amount of mentos. We also didn‟t have a reliable measuring device to get a fully accurate height. We had a tape measure at the wall, and had a video recorder in case we missed the height. Especially for the 40 mentoe test, we had to estimate the height because we were too busy worrying about the slash of soda that we just got on our bodies. As an end result, we did discover that the amount of mentos really does have an affect on the height of the stream. Although we didn‟t get completely accurate results, the height of the eruption did climb, the more mentos we put into the liter of coke. From the 5 mentoe test to the 10, the height climbed 0.07 meters and from the 10 mentoe test to the forty, 2.41 meters. That was all we needed to prove our hypothesis. (The more mentos will create a bigger eruption) We had a fun time, and found that setting a record is harder than it looks.

REFERENCES: “Mentos.” Wikipedia, The Free Encyclopedia. 2008. September 9, 2008. http://en.wikipedia.org/wiki/Mentos (world record) Rachel Cutler and Emma Smith. Guilford Journal of Chemistry. Volume 1. Pages 6-12. (2008) (structure of the lab report, expectations guide) Mike Moalli and Steffi Marsh. Guilford Journal of Chemistry. Volume 1. Pages 13-16. (2008) (graph/results guide) Carly Clark and Jenn Agamie. Guilford Journal of Chemistry. Volume 1. Pages 17-18. (2008) (procedure guide)

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A New Accelerant for the BatMobile By Tim Brooks and Ashley Chello

Summary: The experiment tested was to see whether or not Diet Coke and Mentos had a strong enough force to move a toy car. The reaction of Mentos and Diet Coke has always been a mystery, but the wonder if the combination makes a force that is powerful enough to move things, has been solved.

Introduction: This experiment tested something both different and interesting. It was a test to see if a car can accelerate with the help of Mentos and Diet Coke. It was proven true. During this experiment, the hypothesis was, „If more Mentos are added to the Diet Coke, then the toy car with go farther.â€&#x; There have been experiments with making Mentos Rockets ( 1) and the Mentos reaction height higher but there has not been an experiment along the lines of using it as an accelerant. This is a unique and new way of making toy cars work and move. In this experiment, the group conducted a lab that tested the possibility that using Mentos and Diet Coke will move a toy car. It was successful in making the car move and the group found that the Mentos and Diet Coke lengthened the distance that the car traveled. The control of the experiment was using no Mentos at all. The car along with the Diet Coke taped on top, was tested on the ramp and was found that it traveled a shorter distance then the other trials. The first trial added four Mentos to the Diet Coke. The second trial added six Mentos to the Diet Coke. Both of these trials had an increased distance from the control. Although the experiment was successful, the hypothesis was wrong. Interestingly enough, the trial with only four Mentos traveled a longer distance then the one with six Mentos. Errors might have contributed to the different distances but both were able to show that with the force from the Diet Coke and Mentos, the car was able to move.

Experimental: 1. Begin by gathering duct tape, a toy car (long enough to fit a 2 liter bottle of Diet Coke on it), 3 two liter bottles of Diet Coke, two strips of Green Apple Mentos, a 2x4 piece of wood, a chair, a 25 foot measuring tape, 2 tooth picks, a 2 inch nail, a hammer, a clear, outside area, and safety goggles. 2. Start by making holes in the center of ten Green Apple Mentos with the nail and hammer. 3. Pour out Diet Coke until the soda is at the logo of the Diet Coke. 4. Tape one of the three 2 liter bottles to the toy car. Have the bottle lying on the car, the opening of the bottle pointing to the back and the bottom of the bottle pointing towards the front. Tape it in the center of the car, as straight as possible 32


5. When there are holes in all ten of the Mentos, stick 4 Mentos on one tooth pick and 6 on another. 6. On a flat, clear surface outside tape the 2x4 to the edge of the chair seat. It will make a ramp. 7. Align the measuring tape as straight as possible next to the pathway that the car will be traveling down. 8. Put on safety goggles 9. Test the control to see how far it goes without any Mentos. 10. Put the bat mobile with the Diet Coke at the top of the ramp and let it go. 11. Record the distance the car traveled on your data sheet 12. Test the trials that have Mentos along the same lines. Be sure that when the Mentos are dropped that you have safely released the car as it starts to fizz up.

Results: We tested the effect of a mentos powered car in three different trials. In the first trial we held our controlled experiment where we let the car roll down the ramp by itself without the mentos jetpack. This resulted in the car only traveling 2.15 meters. In our second trial, we duck taped the two leader diet coke to the car so the caped end was facing backwards. Then we added four mentos to it as we released it down the ramp. With the addition of the four mentos, the car traveled a total of 8.33 meters right to the end of the tape measure. Lastly, in our third trial we used the same amount of diet coke in a two leader bottle, but we added seven mentos to it instead of four. This resulted in the car traveling only 4.4 meters. Both the 1st and 2nd trials preformed smoothly without any serious error in the car making it the length of the track. But in the 3rd trial we noticed that the front bumper of the car made contact with the sidewalk as it dismounted the ramp. This caused the car to loose much of its speed that was gained by the exploding soda.

33


How the Number of Mentos Effects the Distance Traveled

Distance Traveled (Meters)

9 8 7 6

Zero Mentos

5

Four Mentos

4

Six Mentos

3 2 1 0 1 Number of Mentos

Conclusion: In conclusion, our hypothesis was correct. We predicted that the more mentos that were added to the car, the further the car would travel. We tested our hypothesis in three different trials, a control, and two other trials with the coke, but different amounts of mentos. In the 1st trial, we tested our control, which involved letting the car roll down the ramp with no other force besides gravity. This resulted in the car traveling 2 meters. In our 2nd trial, we attached a two letter diet coke bottle to the 34


car so that the capped end was facing towards the end of the car. We then added four mentos to the bottle and released the car so that the eruption could start as the car was rolling down the ramp and onto the pavement. This resulted in the car going a further distance of 8.25 meters. In our 3rd and final trial, we added another coke bottle, but kept it in the same position. Instead of adding four mentos, we added seven. This resulted in the car only going 4.18 meters. We discovered after examining the car after the trial, that as it disembarked from the ramp, the front bumper made contact with the pavement. This caused the car to loose much of its velocity and therefore the car traveled a shorter distance. This was one of the many errors that may have taken place in this experiment. Other errors that may have occurred were, human20error, and mechanical trouble with the materials. Human error was the easiest kind of error to make in an experiment that requires so much human work and measuring. It is possible that the two trials that the soda was used in may have been slightly different in a few ways. One soda may have been more carbonated than the other or the angle at which they were mounted to the car was slightly different. There were many small errors that were possible. Other than human error, mechanical problems with our material may have caused some influence on the total distance to take place. It is possible that while performing the trials with the soda, that some soda may have spilled into the car, thus resulting in a larger total weight for the 3rd trial to push. Lastly, there was also the problem with the terrain that the car was rolling on. It was a sidewalk that had many cracks and crevices. This may have influenced the total distance of the car because it didnâ€&#x;t follow the same specific track in each trial. To summarize, our hypothesis was correct in which the car with the soda explosion on it traveled a further distance than a car without any means of chemical acceleration. But because of error our idea of how much the mentos make a difference can not be compared accurately.

References 1. http://www.metacafe.com/watch/748953/mentos_diet_coke_rocket_missile/

35


The Effect of Diet Drinks on the Height of a Mentos Eruption By Lauren Cutuli Summary: This study tested the effect of different types of diet drinks on the height of a mentos eruption. I tested a twelve ounce bottle and five mentos for each trial, and conducted two trials per drink. Diet Tonic Water produced the greatest eruption with a height of .31 meters and .27 meters. Diet Coke had an explosion of .30 meters and .25 meters. Diet Dr. Pepper had an explosion of .21 and .23. Sprite Zero created the smallest eruption with the results, .19 meters and .21 meters. Introduction: The experiment I conducted is one that is different from the norm, especially while using a tonic water drink. In many drinks, there is an invisible carbon dioxide gas that is released after a bottle is opened. Also, inside the drink, water does not let the carbon dioxide bubbles expand. When the mentos are dropped inside the drink, the gum arabic and the gelatin separate the carbon dioxide gas allowing bubbles to expand and form new ones as well.1 The weight of the mentos plays a role in this experiment as well. As the rather heavy candy falls down towards the bottom of the bottle, carbon dioxide is released. The amount of pressure given off by the carbon dioxide pushes the drink out of the bottle.2 Experimental: The design of my experiment was to test the reaction of mentos and different types of diet drinks. I tested four different types of drinks; Diet Coke, Diet Dr. Pepper, Sprite Zero and Diet Tonic Water. I conducted two trials per drink by using mentos to drop into each one. A meter stick was held by the soda so that when the drink erupted, a measurement could be recorded. I used twelve ounce bottles for the drink and five mentos per trial. Procedure: 1. Gather two twelve ounce bottles of Diet Coke, Diet Dr. Pepper, Sprite Zero and Diet Tonic Water 2. Gather three packages of mint flavored mentos and a plastic tube with a hole at the bottom 3. Get a meter stick for measurement records and have someone help hold the meter stick for you 4. Get and put on safety goggles 5. Place the bottle in the sink 6. Put five mentos in the tube with a toothpick at the bottom, keeping the mentos secured 7. Open the top of the bottle 8. Place the tube in the top of the bottle 9. Remove the toothpick 10. Record the height of the eruption 11. Repeat all steps for the same type of drink then again for additional drinks to complete two trials each

Results:

36


The Effect of Diet Drinks on the Height of a Eruption(m)

Height of

Mentos Eruption 0.4 0.3 0.2 0.1 0 Diet Coke

Diet Dr. Pepper

Sprite Zero

Trial One Trial Two

Diet Tonic Water

Type of Diet Drink

Trial One Diet Coke

Trial Two 0.3

0.25

Diet Dr. Pepper

0.21

0.23

Sprite Zero

0.19

0.21

Diet Tonic Water

0.31

0.27

Conclusions: My conclusions show that the Diet Tonic Water and Diet Coke were reactive drinks when mentos were put in the bottle. The Diet Tonic Water, after both trials, recorded the highest eruption with the heights of, .31 meters and .27 meters. Diet Coke was the second most reactive drink, from my results, with the combination of mentos. The heights for this drink were .30 meters and .25 meters. Diet Dr. Pepper was the third most eruptive drink and the measured heights for this diet drink were .21 meters and .23 meters. Lastly, the Sprite Zero had the smallest reaction towards the mixture with mentos and the heights were .19 meters and .21 meters. References: 1. For information about Mentos eruptions: (http://www.newscientist.com/channel/fundamentals/dn14114-scienceof-mentosdiet-coke-explosions-explained.html) 2. For a historic record about Mentos eruptions: (http://www.stevespanglerscience.com/experiment/00000109)

37


Communications (summaries only) Discovery of the Worlds Longest Mentos Eruption: One Hour and Forty Minutes. By Sam Taylor and Will Schaffer Melted mentos and diet coke will create a sustained eruption lasting consistently over one hour in duration.

Drilling a 5 mm Hole in a Mentos Candy Results in a 20% Increase in Eruption Height. By Nick Hill and Kyle Gaboury Modified mentos were tested in 1 liter Mentos candies eruptions.Eruption heights were 95 cm for standard mint mentos candies, 20 cm for mint mentos candy powder, 65 cm for mint mentos with the coatings removed, and 120 cm for mentos candies with a 5mm hole drilled in the center.

Karo Soda Cold SyrupIncreases Quenchesthe theHeight MentosofEruption a Mentos Eruption By Andrea Cawley, By Morgan KelseyEhrler, Robinsand andPam Laura Salmeron Turcio A simulated The effect of volcano soda temperature eruption using ondiet the coke, height mentos, of a mentos corn syrup, eruption andwas redinvestigated. food coloringInproduced a side byno Mentos side study, eruption cold diet whatsoever. coke produced It is suggested, an eruption but ofhas 275not cm,been compared tested, tothat 150 Karo cm for Syrup roomistemperature the ingredient diet coke which quenches this reaction. . Mentos Sliced in Half will Double the Height of a Mentos Eruption

By Emilyâ€&#x;s Ring and Kipness In a height-comparison study of the Mentos eruption, it was found that average eruption heights were 58 cm for a cleanly sliced half-mentos candy, 35 cm for crushed mentos, and 25 cm for unmodified mentos candy.

Serendipitous creation of a Mentos Rocket Several researchers have confirmed that cold or warm mentos erupt By higher Alex Jagielski than room andtemperature Eric Hedberg. mentos, including Andrew Austin and Rachel Spadacenta, Ray Trombetta and Brad Tucker, Kevin Kelly andtaping By Matt Husted, an inverted, Kiersten drilled Kenefick graduated and cylinder Kristen Fradiani to a 2 L bottle of diet coke, a visually stunning sixway horizontal eruption was created. During one of these trials the taping came loose, resulting in a three meter upward flight of a mentos rocket. If developed safely, this could form the basis for numerous mentos ballistics investigations.

38


Unit 3: Matter How do we find out what everything is made out of?

Look around you. What do you see? In front of you are all kinds of stuff- all sorts of matter. Some of this matter you can see, and there’s more that you can’t. Some substances, such as those in your body, are undergoing transformations as we speak. And most of it is all mixed together, which complicates things further. What’s it all made out of? It’s a big mess. What we need to make sense of it is a way to sort things out.

Our primary goal for this unit is to classify the matter that is all around us. First, we’ll consider what we can say about mixtures. As you might guess, not very much…it varies from sample to sample. So, we will explore some purification techniques. We will spend the remainder of our time finding out what we can about pure substances- these are the materials that the universe as we know it is made from. And since nearly all understanding of matter begins with pure substances, purification is the first step in chemical research.

Here’s the plan:

Lesson 1: Introduction to matter. Classifying mixtures. Separation techniques. Lab: Separation Experiment pre-lab. Lesson 2: Pure matter and it’s properties. Lab: Separation Lab. Lesson 3 States of matter. Liquid crystals and plasmas. Lab: Chromatography. Lesson 4: Review for Matter test. Lab: Complete chromatography lab. Lesson 5: Matter test.

1


1. What is it? 2. Mixtures: types 3. Mixtures: purification 3. Pure matter and it’s properties 4. States of matter 5. Liquid crystals

What is everything made out of? matter What is matter? Anything that has mass and occupies space How do we find out what everything is Classify it made out of? We need to Matter is either a Element

Molecule

Constant properties

or a

Mixture

Properties vary Separation needed

Unit 3 Dr. B.’s ChemAdventure

2

Matter

2


1. What is it? 2. Mixtures: types 3. Mixtures: purification 3. Pure matter and it’s properties 4. States of matter 5. Liquid crystals

Element, molecule, or mixture?

gold element

ocean mixture

milk mixture

copper

glass

element

molecule

Think of an example of each. Element:

Molecule

Mixture

3 Unit 3 Dr. B.’s ChemAdventure

Matter

3


4


Names______________________________ Separation Lab

Period____________ Lab3.1

10 Points

Chemists typically spend more than half of their time purifying substances- separating them into their individual pure components. In this lab you will be given a mixture of 5 solid ingredients. Typically, these are sand, sugar, salt, iron filings, corn kernels, and pebbles. This year, they are: 1:_______________ 2: ______________ 3: ______________ 4: ______________ 5: ______________ 6: ______________ Your goal is to separate all ingredients of your mixture quantitatively, and analyze your results. You will be graded based on your choice of methods, your report, and how close your amounts are to the actual amounts provided. Tonight: Discuss this with your partner and come up with a plan. Write it as a diagram below. You are welcome to use any equipment in the lab as long as you work safely and have it approved by me. Be ready to begin your experiment the following day. You will be allowed to dry any wet samples overnight. Note that no student has yet come up with a quantitative method to separate salt from sugar. Sample Separation Scheme

pebbles Iron filings Method salt sugar sand

sand Iron filings pebbles

pebbles

Iron filings Method salt sugar

salt

Method Iron filings

Iron filings salt sugar

salt Method sugar

5


Most common errors: -No separation or only partial separation of salt and sugar. -Samples still wet after overnight drying. 1. Homework: Draw a neat diagram showing how you will separate the mixture, using the same general format as the scheme shown on the previous page.:

Approval stamp:

2. In class: Receive your approval stamp on the bottom of the previous page. Get your mixture. 3. Record the total mass of your mixture: _______ g. Begin your experiments! Record your procedure and observations below. Be sure a stranger could repeat your procedure.

The following day, record your results: 4. What are the masses of each separated component? (You will be allowed one day for drying if any of your samples are wet). Component 1 = __________. Mass: _____ Component 2 = __________. Mass: _____ Component 3 = __________. Mass: _____ 6


Component 4 = __________. Mass: _____ Component 5 = __________. Mass: _____ Component 6 = __________. Mass: _____ Total Mass:________ 5. Based on the mass of your starting mixture and total mass of isolated ingredients What is your % error?

6. What is the likely source of your % error?

7. Analysis. Write a paragraph summarizing your experiment, and reflect on the results. Be sure to include recommended improvements if you were to repeat the process. Use additional paper if necessary.

7


Name_________________________________ Period_______________

ws 3.1

Elements, molecules and mixtures worksheet What is everything made out of?

The universe as we know it has about 100 elements. Occasionally we see them in their isolated form- for example an engagement ring may be pure gold (Au), with a diamond on it, which is pure carbon (C ). More often we see the elements combined to form molecules, such as water (H2O) or table salt (NaCl). Sometimes called compounds, molecules are made out of multiple elements which are bonded together and they have constant physical properties. For example, water freezes at 0 oC, and table salt melts at about 2000 oC. If we look closely at the things around us, we find that most of them are mixtures of molecules. Drinking water, for example, is mostly made out molecules of water, but also has some molecules of salts (like NaCl) and may have added fluoride as well. Classify each of the materials below as an element, molecule, or mixture. The examples below should help get you started. It’s OK if you miss a few‌this is to get us thinking about what things are made out of. A key will be passed out after you complete this. Element, molecule, or mixture? A. Silver Answer: Silver is an element (Ag). B. Air Answer: air is a mixture of nitrogen (an element), oxygen (an element), and, among other things, carbon dioxide (a molecule). C. Ice Answer: ice the solid form of water, which is a molecule (H2O). Classify the 19 materials on the next page, then check the answer key to see how you did. 8


Element, molecule, or mixture? Material A. Silver B. Air C. ice 1. Mud 2. sugar 3. steam 4. Baking soda 5. Alumninum foil 6.brass 7. blood 8. Bubble gum 9. gatorade 10. chalk 11. glass 12. Soy sauce 13. grasshopper 14. gasoline 15. urine 16. snow 17. milk 18. tobacco 19. Pencil lead (graphite)

Element? 

Molecule?

Mixture? 

20. Look around you. Try to find examples of elements, molecules, and mixtures in front of you right now. 1. An element in front of me right now is _____________ 2. A molecule in front of me right now is_____________ 3. A mixture in front of me right now is____________ After you have completed this, we will discuss the answers and provide you with a key.

9


Name___________________________________Period_________

ws3.2

Introduction to Matter and Purification Worksheet 1. The essential question that we will be asking all year is:________________________ _____________________________? 2. This unit on matter is our first chance to take a shot at answering it. Our first observation is that most of the matter around us is not pure- it is a _____________ of substances. Air for example is a mixture of many substances, including nitrogen, oxygen, and carbon dioxide. 3. What is a heterogeneous, and what is a homogeneous mixture?

4. In this room I see wood, glass, aluminum foil, water, a cup of coffee, and tortilla chips. Describe each as a pure substance, a homogeneous mixture, or a heterogeneous mixture.

5. Give two examples of liquid-solid homogeneous mixtures:

Suggest a method for isolating: 6. Pure water from drinking water 7. Individual ink pigments from a magic marker 8. Salt from salt water 9. Oxygen from the air 10. What is the difference between an element and a substance?

11. In order to understand what everything is made out of, all mixtures must be separated into their individual substances. Why?

10


11


12


13


Names______________________________ Period_______

Leaf Pigment Chromatography Lab

lab3.3

20 Points

Pre-lab: Please read the introduction and answer the questions. Introduction New England is famous for its dramatic fall foliage. Every fall “leaf peepers” come from all over the country to witness the explosion of colors the blanket our Connecticut landscape. Some years are bright and bold, others muted and sublime. Every year is different, and every leaf is different. Our goal is to isolate and identify the individual chemicals that create this show. Today after school collect some fall leaves. We will analyze them the following day. Background: Light is a form of electromagnetic radiation. The different colors of light we see are a combination of many reflected wavelengths that vary from 380 - 750 nm (nanometers) in length. Each wavelength also has a specific amount of energy measured in particles, called photons. In general, shorter wavelengths have more energy than longer ones. Every leaf contains hundreds if not thousands of individual chemicals. We’ll focus on three visible groups with characteristic fall colors: the carotenes, xanthophylls, and chlorophylls. Their chemical structures and typical colors are shown on the following page.

14


Leaf Pigments

Carotenes: Gold to Orange O

O

Xanthophylls: Light Yellow

N

N

Mg N

N

O O

O O

O

Chlorophyll A: grass green O O

O

O

O

N N

Mg N

N H O

Chlorophyll B: Olive Green

We can separate the different pigments found in leaves by using paper chromatography. First we’ll mush up the leaves in ethanol to dissolve the chemicals. Then we’ll spot the solutions on some paper,

15


and put them in a jar that contains some solvent and let the solvent rise up the paper, separating the chemicals based on how strongly they adhere to the paper. Reading a chromatogram The distance your chemical travels up the paper is called it Rf value. If it didn’t move at all if has a value of zero. If it went as high as the solvent did it that is a value of 1. Here is a spot with a Rf value of about 0.75:

* CAUTION: The leaf extract and the chromatography solvent contain aromatic organic solvents. It is very important that you do not breathe the fumes from the solvent. Be very careful with this solvent and wash your hands thoroughly after this exercise. The leaf extract will stain clothes. Do not spill either the leaf extract or the chromatography solvent. If there is an accidental spill, notify your instructor immediately. In this lab we will isolate the four substances shown on page 2. For those drawings to make sense, included in this pre-lab is a brief lesson on: Reading chemical structures Chemical drawings of carbon-based molecules are usually written in a form known as shorthand notation, based on the following rules: a. Most contain H, O, N, and C, where hydrogen tends to form one bond, oxygen two, nitrogen three, and carbon forms four bonds (HONC if you love chemistry). b. Carbon atoms are not drawn. Instead, any bend or end of a line indicates a carbon atom. c. Hydrogen atoms are also left out. It’s easy to know how many hydrogen atoms are attached because of the HONC rule. See the examples. d. Atoms other than carbon or hydrogen are included in the chemical structure. e. A more detailed type of drawing molecules called bond notation is also used, where every atom is drawn. The examples on the next page show how this is done: Examples: Ethyl alcohol is drawn in shorthand notation as:

16


O

H

Which we can re-draw using bond notation as:

H

H H

C

C

O

H

H H Note that the HONC rule is obeyed: each hydrogen atom has one bond, oxygen two, and carbon four. Here’s another molecule known as tetrahydrofuran, shown in shorthand and bond notation

H

O

C

H H shorthand notation for tetrahydrofuran

H

O C C

C

H H

H H

bond notation for tetrahydrofuran

Note that tetrahydrofuran has 4 carbons, 8 hydrogens, and one oxygen: it has a molecular formula of C4H8O. Pre-lab questions 1. Complete the following table by filling in the four rectangular areas: molecule shorthand bond notation notation

cylohexane

molecular formula C6H12

H

H

butane

H

C

C

H H H

C

H

H

C H

H

N pyridine C5H5N

17


2. Here are the typical Rf values of a leaf chromatogram: Molecule Carotenes Xanthophylls Chlorophyll A Chlorophyll B

Rf value 0.8 0.7 0.5 0.45

Draw what your leaf chromatogram should look like tomorrow, identifying each spot, and use a colored pencil to indicate it’s color.

3. Draw beta-carotene using bond notation below, and give its molecular formula. (The shorthand notation for this molecule is on page 2).

Tomorrow, bring to class several leaves of a known type. Draw your leaf here and identify the common name of the plant:. Common Plant Name ____________________________. That completes the pre-lab. _________________________________________________________________________ Leaf Chromatography: Procedure: Your lab instructor will demonstrate how to prepare your leaf sample and chromatograph it. (Instructors: use about two mL of acetone for dissolving leaf in mortar and pestle, and use 95% hexanes/5% acetone for chromatography solvent: all 4 bands can be separated using this procedure. Attach your chromatogram and identify the location and Rf values of the carotenes, xanthophylls, chlorophyll A, and chlorophyll B.

18


Name______________________________Period________________3ws3.1L2 Introduction to Matter Summary Worksheet Wordbank (not all of the words are in this story) Crystalline Amorphous Matter Substance Compound Solid Gas Heterogeneous Homogeneous Liquid crystal Liquid Sublimation Deposition Boiling Melting Condensation Chemical Physical Silicon Oxygen Ozone Precise accurate

19


While walking down the beach one day, I spied a small object. I noticed it has both mass and took up space, so I was sure it was ___________. I picked it up and took a look at it under a magnifying glass. I could not see any impurities in this glassy object, therefore I was pretty sure it was _____________________. I assumed it was pure, so I classified it as a ____________________. I took it home and heated it over a fire, but it did not melt, so I can’t really say anything about that __________________(physical, chemical) property. I hammered it and it did not flatten; it is not _____________. I tried to stretch it and could not; it is not _______________. This material is a colorless solid. By the way, The other states of matter are ___________, _____________, and _____________. A few believe that _____________ represent a fifth state of matter, and this phase could either be in a ____________ or _____________ state. My little rock is just a simple solid. Since it is shiny I could say it is ___________. If I had the right equipment I could heat it up to a liquid (_________ it), or perhaps even heat it further from a liquid to a gas (_______________). It’s possible that when I heat it up it might go directly to a gas (_______________), but I doubt it. I do know that iodine vapors can cool directly to form a solid (_______________), but that has nothing to do with my story. I happened to have some hydrofluoric acid kicking around, and when I dropped in my substance to that nasty acid, it dissolved. That _____________(physical, chemical) change was weird. I sent it out to an analysis lab and they told me that my 600 milligram sample consisted of 280 milligrams of Si (_______________), and the rest was O (_______________). The percent composition of my sample is therefore _______% Si, and ________% O. And I thought my substance was a pure element, but really it is a just a _________. I submitted several similar samples I found at the beach and they all gave exactly the same analysis; this data is very ___________. I assume the people at the lab know what they are doing so it is probably __________ as well. My substance is______________.

20


How to ace the Matter quiz

Howtoaceitunit3

Be able to provide detailed answers to the questions below. Have a thorough understanding of the concepts below. Be able and ready to separate a mixture if given one. 1. What is matter? Matter is_____________________ 2. What is a substance? A substance is a __________ _________ or ____________ 3. What is a physical property? 4. What is a chemical property? 5. How could I separate sand from aluminum powder? 6. What are the states of matter? 7. Where can I observe plasma? 8. What are liquid crystals? 9. What are the two types of liquid crystals and how do they differ? 10. Describe the six conversions of matter states (boiling, melting‌)

11. What is the law of conservation of mass?

12. Define malleable and ductile and give examples of each. 13. Heterogeneous mixture = ___________________; homogeneous mixture =___________________ Homogeneous mixtures can be solid/liquid (______________), liquid/liquid (______________), gas/liquid (______________), gas/gas (______________), or even solid/solid (______________). 21


14. How to separate mixtures a. Sugar from sand b. Iron from sand c. Water from the ocean d. Blue ink from black ink 15. What is an element? 16. What is a compound? 17. Why is chromatography such a powerful method for the separation of chemical mixtures? 18. Draw a chromatogram of a sample that has a Rf of 0.75 19. What does HONC mean? 20. Draw methanol, CH4O, using both bond and shorthand notation

21. Draw butane, C4H10, using both bond and shorthand notation‌can you assemble it another way?

22. What is the periodic table?

22


The Atom Unit 4 How do we know that Atoms Exist?

Our Essential Question:

All year we will be trying to answer a simple question: What is everything made out of? Right now, we can say that everything is composed of matter. True, but it doesn’t tell us much. We also have heard that matter is composed of individual atoms. But‌how do we know that is true? People have been asking themselves that question ever since Democritus popularized the idea 2400 years ago. We will be asking ourselves the same question this week: How do we know that atoms exist? To help answer this question we will take a look at how this question has been answered historically up to 1907, at which point most scientists believed the evidence was overwhelming. We will also work together on a project to find modern visual evidence - real pictures - of individual atoms.

Day 1:

Day 2:

Day 3:

Day 4:

Day 5:

Here is the tentative plan: Lesson: History of the atom presentation. Lab: Seeing the atom web-based project day 1 of 2 Homework: History of the atom worksheet Lesson: The atom Lab: Seeing the atom web-based project day 2 of 2. Homework: Lesson: Percent composition, average atomic mass, and isotopic abundance Lab: Rehearse Seeing the Atom presentations Homework Lesson: AtomTest Review Lab: Seeing the Atom Presentations Homework: Review for test Atom Test Introduction to Unit 5: Electrons.

1


The Atom How do we know that Unit 4 the world is made out A historical approach. of atoms? 400 BC

1907

What would convince you? write it below

1 Unit 3 Dr. B.’s ChemAdventure

Matter

The atom: Early Ideas Symbol Inventor

Idea The atom

Democritus

400 BC

Aristotle

Earth, air, fire, and water

400 BC

toxicology Paracelsus

1500 AD

Their Evidence:

Unit 3 Dr. B.’s ChemAdventure

Nothing!

2

Matter

2


First Evidence for the atom Mg + S

24 g 32 g

Mass is conserved Lavoisier

MgS

56 g

Atoms combine in small whole numbers

Dalton

3 Unit 3 Dr. B.’s ChemAdventure

Matter

• Mass percent ws

What is the atom made out of?

1. The Crooke’s Tube Mystery

4 Unit 3 Dr. B.’s ChemAdventure

Matter

3


Thomsons 1897 experiment: Are you convinced?

1. Bends “light”

2. Moves a propeller

3. 1000X smaller than a hydrogen atom • Proposes: The Electron • Thomson 5 Unit 3 Dr. B.’s ChemAdventure

Matter

Where are the electrons?

Rutherford’s 1907 Gold Foil Experiment Conclusion:

Most particles go right through the ultra-thin Gold foil.

Rutherford

nucleus

1. Electrons are outside the nucleus 2. The atom is mostly space But..No idea of electron organization 6

Unit 3 Dr. B.’s ChemAdventure

Matter

4


The atom. Evidence-based Ideas: Inventor Symbol Concept Mass is conserved

Lavoisier

Atoms combine in small whole numbers

Dalton

Electron

Thomson

Nucleus

Rutherford

7 Unit 3 Dr. B.’s ChemAdventure

Matter

d Rut her for

T ho mso n

Dal ton

isie r Lav o

lsus Par

ace

otle Aris t

Dem ocri tu

s

The atom: 400 BC-1907

• Brief video summary:1:00-1:57

Unit 3 Dr. B.’s ChemAdventure

8

Matter

5


Atomic Particles

• Video: 1:55-3:38

Particle

Charge

Mass #

Location

Electron

-1

0

cloud

Proton

+1

1

Nucleus

Neutron

0

1

Nucleus

Atomic Number = # of protons = Z “the blue number” 2He

Correct?

Yes

Unit 3 Dr. B.’s ChemAdventure

The atom song

Element

32S

# of protons = Z

Carbon

6

Phosphorus

15

Gold

79

No

9

Matter

Ions, Mass Number, and Isotopes

Protons Electrons

1 1

1 0

1

2

What is it?

H

H+ H-

+= cation -= anion

1. Ions: Different # of electrons.

3. Isotopes: Different

2.Mass Number

# of neutrons. Symbol

Protons + neutrons

p+

n0

e-

Oxygen - 18

8

10

8

Oxygen -

8

9

15

16

17

Phosphorus- 31 Unit 3 Dr. B.’s ChemAdventure

Mass # 18

8

17

15

31

18 8

O 17 8

31

O

P

10 15

Matter

6


Determination of average atomic mass

• Element X has 2 isotopes: • Isotope a 10 protons, 10 neutrons. • Abundance: 40%

• Isotope b has 10 protons 11 neutrons • Abundance: 60%

• What is the average atomic mass of Element X? • Solution: • (0.4)(20) + (0.6)(21) =

• 20.6 amu • a.a.m = sum of (abundance)(mass #) Unit 3 Dr. B.’s ChemAdventure

11

Matter

You try one: Element Guryanovium (Gu) • P N • 15 15 • 15 17

abundance Average Atomic Mass? 66% • 30.68 amu 34% How many neutrons is too many?:

The “Band of Stability” • In general •

n/p >1.5 = unstable = radioactive • All elements >82

Unit 3 Dr. B.’s ChemAdventure

Matter

Elements and isotopes video 3:40-7:40

12

Ions: 7:40-9:30

7


You try one: Element Guryanovium (Gu) • P N • 15 15 • 15 17

abundance Average Atomic Mass? 66% • 30.68 amu 34% How many neutrons is too many?:

The “Band of Stability” • In general •

n/p >1.5 = unstable = radioactive • All elements >82

Unit 3 Dr. B.’s ChemAdventure

Matter

Elements and isotopes video 3:40-7:40

12

Ions: 7:40-9:30

How do we know that atoms exist? Unit 3 Dr. B.’s ChemAdventure

Matter

d

Rut her for

mso n T ho

Dal ton

isie r Lav o

lsus P ar

ace

otle Aris t

Dem

ocri tu s

End Atoms. Next: Electrons 

13 video

8


Name__________________________________ Period________

lab4.1

How do we know that atoms exist? Images of the Atom Project 30 Points UPDATED 10/15/2008 Introduction All year we will be trying to answer a simple question: What is everything made out of? Right now, our best answer may be: everything is composed of matter. True, but it doesn’t tell us much. Another answer many be that all matter is composed of individual atoms. But…how do we know that is true? People have been asking themselves that question ever since Democritus popularized the idea 2400 years ago. We will be asking ourselves the same question this week: How do we know that atoms exist? To help answer this question we will take a look at how this question has been answered historically up to 1907, at which point most scientists believed the evidence was overwhelming. But most of you have indicated that the most convincing evidence for the existence of an atom would be to observe one. The goal of this project is to provide as much compelling visual evidence as you can that atoms do in fact exist. An important warning: Beware of doctored images on the web…anyone can create a fake image of an atom; we are looking for the real thing. A scoring rubric for this project is on the next page.

9


Scoring Rubric for Seeing the Atom Powerpoints 30 Points Your score will be based on completing each step below. Use the 1989 IBM image as a model when preparing your 2 pages, and check off each item on the list below. 1. Topic Chosen from the list given on following page (2 points) Your own topic chosen: 5 bonus points 2. Two page PowerPoint on your topic Submitted in color (2 points) Page One: Includes at least 2 relevant atomic scale images on page 1 (2 points) Images are authentic images of atoms, and if not an explanation is given (2 points) An abstract (summary) is included (2 points) The identity of the atoms (carbon, xenon, etc.) is given (2 points) The images are sourced (2 points, see IBM sample for examples) Page Two: A narrative (no bullet-points) description of the research is given that includes: How this research provides evidence that atoms exist (2 points) The device used to create the image is given (2 points) The date of the research is given (2 points) Other interesting information of any type, such as information about the author of the work, is included (2 points) A minmum of three references are included (8 points; note high point value): These are not websites- they are either books or scientific journals They are properly formatted (see 1989 IBM image references for proper formatting) They are numbered as endnotes and cited in the text using superscripts that look like this.1 These powerpoint presentations will be printed in color, presented orally, and then posted in the room. Hopefully, they will help convince us what the scientists say is true: that all matter is made out of atoms. A sample presentation is provided to help you complete this project.

10


Images of the Atom Project: Topics Here are some suggested topics that relate to actual images of atoms. Before choosing one, feel free to search the web so that you may discover your own topic. Five Bonus Points to any one who creates their own topic, or who defends the position that images of the atom are artificial: we have never seen the atom with these devices. 1. The 1989 IBM atomic image Suggested website: http://www-03.ibm.com/press/us/en/pressrelease/22260.wss 2. Silicon atoms imaged in 1981…the first images of the atom? Suggested website: http://www-03.ibm.com/press/us/en/photo/22264.wss 3. IBM’s molecular switch Suggested website: http://www-03.ibm.com/press/us/en/presskit/22242.wss 4. The worlds smallest abacus? Suggested website: http://www.research.ibm.com/atomic/nano/roomtemp.html 5. The first 3-dimensional images of atoms using MRI? 6. The scanning tunneling microscope 7. The atomic force microscope 8. The NIST atomic image and hip-hop atomic sound Suggested website: http://www.nist.gov/public_affairs/releases/hiphopatoms.htm 9. The Penn State atomic image 10. Observing the “wings” of atoms Suggested website: http://web.utah.edu/unews/releases/03/jun/orbitals.html 11. Simulation of a virus (note this is a simulation only, but state of the art) 12. Our government at work: atomic images from the National Institute of Science and Technology (NIST). Suggested website: http://www.metallurgy.nist.gov/facilities/TEMgallery.html 13. Gold and other atoms imaged by the National Center for Electron Microscopy Suggested website: http://ncem.lbl.gov/frames/tecnai.htm 14. Aluminum nitride images from Cornell University: Suggested website: http://www.cns.cornell.edu/Nanocharacterization06.html 15. Individual nickel atoms Suggested website: http://radio.weblogs.com/0105910/2004/09/06.html 16. Art and nanotechnology Suggested website: http://www.mrs.org/s_mrs/doc.asp?CID=1920&DID=171434 17. Kanji atomic image: Suggested website: http://www.nanopicoftheday.org/2003Pics/atomkanj.htm 18. Individual atoms on the surface of a microbe Suggested website:http://www.nature.com/nrmicro/journal/v2/n6/fig_tab/nrmicro905_F2.html 19. How big the atoms should be, relatively speaking Suggested website: http://www.camsoft.co.kr/CrystalMaker/support/tutorials/crystalmaker/resources/VFI_Atomic_ Radii_sm.jpg 20. The nanocar Suggested website: http://www.media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=7850

11


Here is a completed presentation that can serve as a guide:

The 1989 IBM Atomic Image

By Your Name Here

Abstract: In 1989 Don Eigler from IBM ushered in the nanotechnology revolution by moving individual Xenon atoms to create the image shown above.

35 Xenon Atoms

Source: http://www-03.ibm.com/press/us/en/pressrelease/22260.wss

Eiglers Lab Notebook

Eigler with his STM Source: http://www.tainano.com/chin/Eigler.htm

Don Eigler (2006)

Source: http://www.theregister.co.uk/2006/06/13/don_eigler_valley/

Source: http://www.flickr.com/photos/jurvetson/456735511/in/set-30000/

12


Don Eigler and the 1989 IBM Atomic Image The question “What is everything made out of” is one of the most fundamental questions of mankind, right up there with “Why are we here?”, and “Will that be on the test?”. Recorded ideas date back over 6000 years,1 first popularized in the west by the work of Democritus. Arguably the most compelling evidence for the atom being the fundamental particle of nature involves the human senses- smell, touch, sight, etc. Because of the small size of the atom, none of these are directly possible, so perhaps the next best thing is to observe it with the help of an instrument. This may have first occurred as early as 1981,2 but the image that popularized it was taken by Dr. Don Eigler in 1989.3 Don Eigler is a ponytailed, well educated physicist and surfer. In 1989, he designed his own scanning tunneling microscope. An image of him with his instrument was taken during a 2006 interview.4 While studying the surfaces of solids, he came up with the idea of limiting the movement of atoms by performing his experiments at a few degrees Kelvin- close to absolute zero. In his own words from the 2006 interview, he found that “Through a combination of hard work, some horse sense and good, old fashioned blind luck, I happened to be positioned to discover that I could manipulate individual atoms with a scanning tunneling microscope.” Having discovered the ability to move individual atoms, Eigler decided to create a work of art to document his discovery. What he created is an image of the letters I B M using the noble gas Xenon, a dense and unreactive colorless gas. Was he forced at gunpoint to do the bidding of his IBM bosses?? According to Eigler: “I made that decision on my own. Management never said anything to me beforehand, and I did it with a very clear purpose in my mind. IBM gave me a job, gave me the opportunity when I needed one, gave me the opportunity to excel at doing the things that I love in life, and it was payback time. I pull no punches on that. It was my way of giving back to the corporation some of what the corporation gave to me.” Does Eigler get bored recounting the discovery, now that two decades have passed? “I don't mind talking to people when they're curious, for instance, about what I was thinking about or why did I do this or something like that. The thing is that I always get introduced to people as the guy who wrote I-B-M in atoms. After you have heard that enough times, you don't really need to hear it five more times.” Eiglers current interests are in the field of Spintronics,5 a speculative field where future computers will be based not electricity (the translational movement of electrons) but on their spin…a sort of electricity where the electrons stay where they are. Sources: 1. Gangopadhyaya, Mrinalkanti (1981). Indian Atomism: History and Sources. Atlantic Highlands, NJ: Humanities Press. ISBN 0-391-02177. 2. G. Binnig, H. Rohrer “Scanning tunneling microscopy” IBM Journal of Research and Development 30,4 (1986) reprinted 44,½ Jan/Mar (2000). Available on the web at http://researchweb.watson.ibm.com/journal/rd/441/binnig.pdf 3. Imaging Xe with a low-temperature scanning tunneling microscope. DM Eigler, PS Weiss, EK Schweizer, ND Lang - Physical Review Letters, 1991 1189-1192. 4. A man and his microscope: IBM's quest to make atom-sized chips. The silver surfer speaks. Ashlee Vance, The Register, June 13, 2006. Available on the web at http://www.theregister.co.uk/2006/06/13/don_eigler_valley/ 5 Spintronics: A Spin-Based Electronics Vision for the Future. S. A. Wolf et al., Science 2001, Vol. 294. no. 5546, pp. 1488 - 1495

13


Name_________________________________________ Period______

4ws4.1

History of the atom worksheet Complete this worksheet after listening to the presentation on the history of the atom from 400 BC to 1907 AD. Refer to the notes on your slides if you need to for each question. 1. What is the essential question for this course? 2. What is the essential question for this unit? 3. What would you need to see, know, or observe to become convinced that atoms exist?

4. By now you have seen a presentation on some ideas and experiments concerning the atom from about 2400 BC to 1907. Fill in the table below to summarize the work and significance of some of the key players. name

Democritus

Aristotle

Paracelsus

Lavoisier

Dalton

Thomson

Rutherford

Symbol

Contribution

5. How is Daltons model of the atom different from that of Democritus?

6. Draw a picture of the Cathode Ray tube used by Thomson:

7. What happened when Thomson put a magnet near the Cathode Ray Tube?

8. Why was that important? 14


9. How big is an electron compared to a hydrogen atom?

10. Draw a figure and explain Rutherford’s Gold foil experiment:

11. Lavoisier’s experiments indicated that mass is never lost when chemical reactions occur. Daltons experiments suggested that elements come in different sizes, and they combine in simple ratios. Thomson showed there is something smaller than hydrogen, and Rutherford showed that there is a lot of empty space in matter. Still, some scientists did not accept at that point that atoms exist. Put yourself in their shoes. Write a paragraph stating why this is still not enough evidence to prove that atoms exist.

15


Name______________________________Period_________________

WS4.2

Atomic Bookkeeping Worksheet:

Atomic Particles, Atomic Number, Mass Number, Ions, and Isotopes Here are some quick facts to help you keep track of the names and numbers associated with the atom:

Protons are in the nucleus, each has a +1 charge, and identifies the element. Neutrons are in the nucleus, each has no charge, and determines the isotope. Electrons are outside the nucleus, each has a -1 charge, and determines the reactivity. Atomic Number is the number of protons. Mass number is the number of protons + neutrons Average atomic mass is the averaged mass for a mixture of isotopes An ion has either more or less electrons than protons, so it is charged. Isotopes vary only in the number of neutrons for an element. 1. Pick an element, any element. My element has the symbol _______, which stands for ____________. It has ______ protons, and when uncharged also has _________ electrons. The average atomic mass of this element is ________ atomic mass units. If it has one extra electron, this would give it a _____ charge. If one atom had two more neutrons than protons, the mass number would be ________ atomic mass units. 2. Fill in the blanks below: Hydrogen 1 H 1.008

____________average atomic mass ____________chemical symbol ____________chemical name ____________atomic number

3. Complete the following table: Element O (oxygen) Zn (zinc)3+ Sn (tin)Fe (iron)3+ C (carbon) H (hydrogen)+ Sg (seaborgium)

Number of protons 8

Number of electrons

Average atomic mass 15.999

16


4 What is an isotope? 5. What is the difference between mass number and atomic number? 6. Draw the complete symbol for the isotope of silver that contains 47 protons and 60 neutrons: 7. Complete the following table. (Note that here we are calculating the mass number for that particular isotope. This is not the average atomic mass) Element Number of Number of Number of Mass number protons electrons neutrons 2+ C (carbon) 6 6 10 12 26 57 Hg (mercury) 204

8. What is the difference between mass number and average atomic mass?

17


Name______________________________

Period__________________________

WS4.3

Atomic mass/average atomic mass worksheet

1. Complete the following table: Element Number of protons O (oxygen) 8 Zn (zinc) Sn (tin) Fe (iron) C (carbon) H-(hydride) Note the negative sign! Sg (seaborgium)

Number of electrons 8

Number of neutrons 9 37

Mass number 17 118

30 14 0

266

2. Mass number and atomic number are easy to confuse. To determine atomic number one only needs to know the number of _____________, whereas the mass number also includes the number of_____________. 3. Chlorine has two naturally occurring isotopes, Cl-35 and Cl-37. The lighter isotope is _____ which contains _____ protons and _____ neutrons. The heavier isotope is _______ with _____ protons and _____ neutrons. 4. Here is a problem that is solved for you. As you read the problem, imagine how you could solve it without a calculator, then see how it is done, and apply the solution to #5. An imaginary element X has two isotopes, one with a mass of 20 atomic mass units (amu), and the other with a mass of 22 amu. They both occur with equal (50%) abundance. What is the average atomic mass of X? Solution: (0.5)(20) + (0.5)(22) = 21 a.m.u. 5. What would the atomic mass of element X above be if the abundances of X-20 was 25%, and the abundance of X-22 was 75%? Solution (fill in the missing numbers: ( )( ) +( )( ) = _____ a.m.u. 6. Silver has 2 isotopes. One has a mass of 106.905 amu (52%) and the other has a mass of 108.905 amu (48%). What is the average atomic mass of this isotopic mixture of silver?

18


Name______________________________ Period__________________________

WS4.4

Isotopes, ions, atomic mass, and average atomic mass worksheet The number of protons, electrons, and neutrons is usually symbolized in an element box in the following manner: For example: 235 41 Mass number

19

(p + + n 0) 24

Charge (p + + e -)

9

Na+

F-

2+

Ca

20

U

92

11

9 protons 10 neutrons 10 electrons

atomic number (p + )

20 protons 21 neutrons 18 electrons

92 protons 143 neutrons 92 electrons

Once the number of each atomic particle is known, it is an easy matter to identify isotopes (atoms that vary only in the number of neutrons) or ions (atoms that do not have the same number of protons and electrons). 1. Fill in the blanks

34

35

16

17

S

___protons ___ neutrons ___electrons

Cl

-

238

6+

U

92

___protons ___protons ___ neutrons ___ neutrons ___electrons ___electrons

32

35

238

16

17

92

S

Cl

4+

U

___protons ___ neutrons ___electrons

___protons ___protons ___ neutrons ___ neutrons ___electrons ___electrons

7 protons 9 neutrons 8 electrons

105 protons 8 protons 132 neutrons 8 neutrons 106 electrons 8electrons

2. Which pairs of elements are isotopes?

3. Which elements are ions? 4. Fill in the boxes below.

1 protons 0 neutrons 1 electron

23 protons 24 neutrons 22 electrons

5 protons 6 neutrons 8 electrons

19


5. Are the following pairs of compounds isotopes, ions, or different elements? Also, provide the full atomic symbol for each substance 20 Example: Ne 10 a. Substance 1: 10 protons, 10 neutrons, 10 electrons: b. substance 1: 10 protons, 11 neutrons, 10 electrons Relationship: isotopes

21

Ne

10

c. Substance 1: 10 protons, 10 neutrons, 10 electrons d. substance 1: 9 protons, 10 neutrons, 10 electrons Relationship:________________ e. Substance 1: 10 protons, 10 neutrons, 11 electrons f. substance 1: 10 protons, 10 neutrons, 10 electrons Relationship:________________ 6. Determine the average atomic mass for the following imaginary elements, using the first question as an example.

Solved Example. Isotope 1: 4 protons, 4 neutrons. Abundance : 91% Isotope 2: 4 protons, 5 neutrons. Abundance : 9% Average atomic mass = sum of (abundances)(mass number) = (0.91)(8 amu) + (0.09)(9 amu) = 8.09 amu a. Isotope 1: 14 protons, 14 neutrons. Abundance: 62% Isotope 2: 14 protons, 16 neutrons. Abundance : 38% Average atomic mass =

b. isotope 1: 94 protons,104 neutrons. Abundance : 52% Isotope 2: 94 protons, 112 neutrons. Abundance: 48% Average atomic mass =

c. Isotope 1: 24 protons, 24 neutrons. Abundance : 40% Isotope 2: 24 protons, 25 neutrons. Abundance : 39% Isotope 3 : 24 protons, 28 neutrons abundance = 21% Average atomic mass =

3. Level One Only: Boron has two naturally occurring isotopes. Boron -10 (abundance = 19.8%; mass = 10.013 amu) and another isotope (abundance 80.2%). The average atomic mass of boron is 10.811 amu. What is the mass of the other isotope? 20


How to ace the Atom unit

Howtoaceitunit4

In this our fourth unit, we explored the atom. Our goal was to answer the question: How do we know that atoms exist? We began with a chronological study, starting with the ideas of Democritus, and ending with the discovery of the nucleus by Rutherford. We also considered what it would take to convince us that atoms in fact do exist, and we found evidence that atoms have been individually observed and moved. We then focused on the three primary subatomic particles. We considered their location, mass and charge, and this led to an understanding of atomic number, mass number, and average atomic mass. Finally, we applied this to isotopes, and finished with the band of stability- the ratio of protons to neutrons for a stable atomic nucleus. In our next unit we will focus on the subatomic particle that determines the chemical behavior of each element: the electron. To ace this unit you should review the powerpoint slides, the atom worksheets, and this study guide. You should also review the results of our Seeing the Atom project. Here are some quick questions on each topic we covered. 1. The history of the discovery of the atom: a. Aristotle and his four “elements� b. Democritus: symbol and what he got right c. Paracelsus: Symbol and contribution d. Lavoisier: Symbol, contribution, and his untimely end e. Dalton: symbol and his major contribution f. Thomson: symbol, what he discovered, device he used, evidence . g. Rutherford: symbol, and his key experiment 2. The 3 subatomic particles, their mass in atomic mass units (amu), and charges

3. Atomic number

Example: What are the atomic numbers for each element in baking soda, NaHCO3? Why can Magnesium never have 13 protons?

21


4. Mass number

Example: What is the mass number of an oxygen atom that has 8 neutrons and 9 protons?

5. Average atomic mass formula

Example: Element X has two isotopes. One has an abundance of 63% and an atomic mass of 10 a.m.u. The other has an abundance of 37% and an atomic mass of 15 a.m.u. What is the average atomic mass of element X?

6. Isotopes- definition (watch out for cases that are different elements, not different isotopes)

Example: How many protons and neutrons are present in an atom of Cs-111?

7. Ions- know how to calculate charge on an atom

Example: How many protons, neutrons, and electrons are present in an atom of C-13?

Example: Draw element boxes that show an example of a fluoride monoanion (-1), and a calcium dication (+2).

8. Nuclear stability

Example: Circle the stable isotopes: U-238 Po-208 C-14 9. Chemical symbols for elements 1-20

What are the symbols for

hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, argon, potassium, and calcium,? 10. How do you know that atoms exist? Provide quantitative evidence in addition to imaging. Be sure to review the Seeing the Atom Presentations from each of you. Good luck on the test. 22


The Electron Unit 5 Our Essential Question: Where are the electrons in an atom? In our previous unit, The Atom, we looked for evidence to support what some have been saying for over 2000 years: that the universe is composed of 82 naturally occurring types of atoms known as elements. Evidence in support of this idea includes the experiments of Thomson and Rutherford, and numerous images compiled since 1955.

But where are the electrons? Rutherford showed that they are in the vast space that exists outside the nucleus of each atom. What purpose do the electrons serve? How are they organized? How do they help explain the molecules, like water, that are all around us, and that we are made out of? To find out we’ll complete our historical look at the atom with the discovery of Niels Bohr, aided by the mathematical breakthroughs of Rydberg and Balmer.

Our plan for the week: Day 1: Lab: Flame Test Lab Lesson: Light Day 2: Lab: Spectroscopy Lab Lesson: Bohrs Epiphany Day 3 Lesson: Electron Configuration Lab: Problem Solving Day 4 Review for Electron Test Day 5: Electron Test 1


Our Essential Question:

Unit 5: Electrons

Where are the electrons in an atom?

X

?

The answer lies in this mystery:

1

And so First, we must understand… Unit 5 electrons Dr. B.’s ChemAdventure

How does light travel? • What happens when we shine a flashlight through a slit?

?

• What happens when we shine a flashlight through two slits?

2 Unit 5 electrons Dr. B.’s ChemAdventure

2


Young’s Double-Slit Experiment: Instructions here; explanation here

1. Light travels in waves

Speed of light = 3 x 108 m/s

2: really fast. short wavelength high frequency

S=wf

long wavelength Low frequency

Speed of light (m/s)

= wavelength (m) x frequency (1/s) Hz

S-1

3

Unit 5 electrons Dr. B.’s ChemAdventure

What is the wavelength of violet light in nanometers; f = 7.23 x 1014 s-1? L2 review scientific notation Here

• S=wf • 3 x 108 m/s = (w)(7.23 x 1014 s-1) w = 3 x 108 m/s • 7.23 x 1014 s-1 • = 4.15 x 10-7 m =0.000000415 m • = 415 nm 4 Unit 5 electrons Dr. B.’s ChemAdventure

3


The Electromagnetic Spectrum

400-700 nm:

Roy G. Biv

constant

often

dangerous

safe

5 Unit 5 electrons Dr. B.’s ChemAdventure

The story of Bohr’s Epiphany Balmer

Hydrogen Rydberg

w(nm) =656, 486, 434, 410…What number is next??

L1:Try it for n = 3

1 w= 1   1 0.01097 2 − 2  w = 656 nm 2 n  6

Unit 5 electrons Dr. B.’s ChemAdventure

4


Bohr sees the connection

w=

Between light and the electron

1 1   1 0.01097 2 − 2  2 n 

XX w

656

486

435

410

397 ?

n

3

4

5

6

7

Electron Emission Is Light 7

Unit 5 electrons Dr. B.’s ChemAdventure

Hydrogen Atom

5

-e

4

434 nm

3  2:

3

2

656 nm

-e

Emission

1

-e

+P

13: absorption

486 nm

-e

-e

410 nm

8 Unit 5 electrons Dr. B.’s ChemAdventure

400 nm

700 nm

5


It all fits.

Bohr

• 1. Jimmy neutron: no • Shells: yes • 2. evidence: emission

nucleus

2 8 18 32

9 Unit 5 electrons Dr. B.’s ChemAdventure

Where the electrons are exactly: Aufbau order (to Argon) shellNuc. 1 2 3

1 2

# electrons total

2 8

orbitals:

Paired electrons

s s, and p

3

18

s, 3p

And d Video animation: 16:54- 17:20

again

Aufbau order to Ar: 1s2 2s2 2p6 3s2 3p6

# electrons

2 2 6 2 6 10

level

Config. orbital # e’s

1s2 2s2 2p6 3s2 3p6 (Soon) 10

Unit 5 electrons Dr. B.’s ChemAdventure

6


1H:

Electron Configuration of… 1s1 2He: 1s2

3Li:

1s22s1 8O: 1s22s22p4

2 2s2 2p6 3s2 3p4 1s S: 16

Orbitals and # electrons: s(2)

p(6) d(10)

f(14)

Orbital Notation

A detailed way to show electron configuration

3Li:

Orbital Notation

1s2 2s1

Electron configuration For each orbital Pauli Principle: electrons pair up with opposite spins Hund’s Rule: electrons spread out within orbital groups 11 Unit 5 electrons Dr. B.’s ChemAdventure

Orbital Notation of Carbon: 6C:

No!

X

1s2 2s2 2p2

1s2 2s2 2p2

Yes!

Hund’s Rule: Electrons spread out within orbitals

Please give the electron configuration with orbital notation for Sulfur

16S:

1s2 2s2 2p2 3s2 3p4

12

Unit 5 electrons Dr. B.’s ChemAdventure

7


Heisenberg’s Uncertainty Principle • We can never know the exact position and velocity of an electron at the same time. • Why? • (Even the smallest amount of energy moves it unpredictably)

13 Unit 5 electrons Dr. B.’s ChemAdventure

“Build up”

Note: 4s< 3d

Aufbau Order

14

Unit 5 electrons Dr. B.’s ChemAdventure

8


[He] [Ne] [Ar]

Aufbau Order

[Kr] [Xe] [Rn] “shorthand Notation” Fill in blank table 1s2

2s2

2p6

3s2

3p6

4s2

3d10

4p6

5s2

4d10

5p6

6s2

4f14

5d10

6p6

7s2

5f14

6d10

7p6

1s22s22p63s2 [Ne]3s2 9F: 1s22s22p5 [He]2s22p5 1s22s22p63s23p64s23d1 [Ar]4s23d1 [Kr]5s24d3 21Sc: 12Mg:

41Nb:

1s22s22p63s23p64s23d104p65s24d3

15

Unit 5 electrons Dr. B.’s ChemAdventure

Principles and rules of electron configuration Principle or rule Heisenberg

(e-position uncertain)

Aufbau (build up) Hund’s Rule (spread out) Pauli (opp. spins)

Bad

1s22p1

1s2 2s2 2p2 1s2

Good

1s22s1

1s2 2s2 2p2 1s2

16

Unit 5 electrons Dr. B.’s ChemAdventure

9


Valence Electrons

• Outermost shell of electrons • Easily predictable from Periodic Table.

1

(2)

2

8

3 4 5 6 7 2 2 2 2 2 2 2 2 22

All 217 Unit 5 electrons Dr. B.’s ChemAdventure

Electron Dot Structures:

• Quick look at valence electrons

Ne

Li

X

Be

Be

No!: always spread out all 8

Try H,O,N,C H O N

C

Valence electrons are the key to understanding: Chemical reactivity Fortunately, it is nicely categorized in our next topic: The Periodic Table

18

Unit 5 electrons Dr. B.’s ChemAdventure

10


The Electron: Lab Experiment, Problem Sets, and Study Guide This Unit includes two experiments, four problem sets, and a study guide. Bohr was fascinated by the brightly colored lights emitted by various chemicals when placed in a flame, and wondered if there was a chemical explanation. You wil create the same colors in the Flame Tests Lab, and use it to identify unknown samples. And between 1907-1913 Bohr and other scientists competed to explain the sharp lines of light that each element forms when heated or charged. Using spectroscopes, you will observe these lines as well in the Spectroscopy Lab, and will be asked to consider why they appear as they do for each element. Since there is a fundamental relationship between light and the electron, you will complete a problem set on Light, and this will be followed by several problems concerning how electrons are organized around the nucleus: Electron Configuration. This includes the idea of pairs, or orbitals organized around the nucleus, and shows us where they are most likely to be, including the direction of spin they are rotating in. We will see that it may be impossible to ever determine where they are and how fast they are moving at the same time.

11


Names___________________________________________Period______________ lab5.1 Flame Tests Lab 20 points Safety Notice: This lab is exciting, but please be cautious. Wear goggles. Assume all salts are toxic, as are all gases produced. Introduction: We have all seen the beautiful colors that can form when substances are placed in a flame. Pockets of gas in wood can form green and blue colors when they ignite. What is happening when this occurs? This answer was the key to unlocking the secrets of the electron, now known as quantum theory. In this experiment we will observe some of these colors, and will make some initial attempts to explain it. Finally, the color of the emitted light will be used to identify the unknown salts. Materials: Bunsen burner; Paper Clips Beaker of water

Salts and unknowns: 1. __________ 2. __________ 3. __________ 4. __________ Unknown numbers:

Procedure 1. Goggles on please, and go to your stations. The rule all year will be that if the instructor is wearing goggles, you are as well. 2. Listen to the Bunsen burner lesson 3. Each student should safely light the Bunsen burner and adjust the gas/air mixture. 4. Turn off Bunsen burner 5. Get your set of test tubes and unknowns 6. Dip the paper clip to see what color it turns on its ownâ&#x20AC;Śif you see this color it may be due to the metal in the paper clip. 6. Dip each of solutions using a paper clip and place in flame for less than 2 seconds each. Write down the color of the flame, and estimate the wavelength in nanometers(a color chart will be available). 7. Fill in table 1 during testing. Identify the unknowns based on flame color. 8. Clean up: wet matches in trash. All stations will be inspected, including sinks. 9. Take your normal seats. 10. Answer questions at your desks. Turn in lab (one per group of two).

12


Chart: Wavelength (in nanometers) of visible light

Table 1: Color and wavelength in nanometers of emission spectrum of salts and unknown. Salt

Flame color

Estimated wavelength (nm)

1. 2. 3. 4. Unknown #_____ Unknown #_____ Analysis 1. Each of the known compounds tested contains chlorine, yet each compound produced a flame of a different color. What does this suggest?

2. We will learn this week that the movement of electrons in atoms produces the colors we observed. What specifically may be going on with the electrons to produce color? (take your best guess)

13


Team Names_________________ and ____________________ Period _____ Lab 5.2

Spectroscopy Lab Introduction: In our previous lab we observed the vivid colors emitted by placing chloride salts in a flame. This was followed by a demonstration where we observed how a spectroscope (a prism, really) can divide up light into separate wavelengths. The purpose of this lab is to combine these two observations by repeating the flame test experiment, this time using a spectroscope. This experiment is similar to that performed by Niels Bohr and others, and begs the question: what does it all mean? How do the spectral lines relate to the structure of the atom? Safety: As before, this lab uses flames and toxic salts. Please wear goggles. Procedure: 1. Put on goggles. 2. Each group will perform a 5 minute experiment at each of 6 stations, and then proceed to the next. As precisely as you can, draw the component wavelengths observed at each station. Follow the instructions for each station, clean up, and be ready to move to the next station. Station 1: Sunlight. Each student should point through the spectroscope directly at the sun, and draw the component wavelengths observed. If weather permits, see if the colors are the same when you are not looking through a window. Station 2: Artificial light Each student should point through the spectroscope directly at the fluorescent lights, and draw the component wavelengths observed: Station 3: Copper Chloride Dip a paper clip into a copper chloride solution, and place it in the flame for less than two seconds while your partner observes the emission of light through the spectroscope. Repeat as necessary, but be cautious not to ignite the splint. Station 4: Magnesium Combustion Request a piece of magnesium metal from your instructor. Holding it in tongs, ignite the magnesium and observe the spectrum through the spectroscope. Warning: The light is extremely bright, and burns at 2000 degrees Celsius. Station 5: Hydrogen gas Turn on the hydrogen gas spectrum tube and observe the component wavelengths through the spectroscope. You should see individual spectral lines.

14


Station 6: ______ Gas Turn on the ________ gas spectrum tube and observe the component wavelengths through the spectroscope. You should see individual spectral lines. Data: Draw what you see through the spectroscope as accurately and precisely as you can. The marks are at 450, 550, and 650 nm. 400

500

600

700

400

1. Sunlight 400

500

600

500

600

700

400

2. Fluorescent Light 700

4. Magnesium combustion

400

500

600

500

600

700

3. Copper Chloride 700

5. Hydrogen Gas

400

500

600

700

6._______

Please answer the following questions at your normal seats: 1. Describe what you observed at each station: 1. 2. 3. 4. 5. 6. 2. Which light source provided the simplest spectrum? 3. Which light source provided the most complex or varied spectrum? 4. What were the wavelengths (in nanometers) of the individual lines from hydrogen in nanometers? 5. What were the colors of the individual lines from hydrogen? 6. Now that you have seen a variety of emission spectra, what do you believe causes the â&#x20AC;&#x153;linesâ&#x20AC;??

15


Name_____________________________ Period_________

WS5.1

Wavelength worksheet

Please show your work, not just the answer ď &#x160;. If you look down from Diamondhead in Hawaii, you will see waves rolling in at a steady rate. Some days they are nicely spread apart, meaning they have a long wavelength. Other days they come in more frequently; this is more dangerous for the surfers. The surfers prefer the long wavelength days. They know that as the wavelengths get shorter, their frequency gets higher, and there is more energy- more danger â&#x20AC;&#x201C; to the high frequency waves. This is summarized in the diagram:

Light travels in the same way. It travels at a steady rate: about 300,000,000 meters per second, or 3 x 108 m/s. And as the wavelength decreases, the frequency must increase:

8

S = speed of light = 3 x 10 m/s

S = wf

w = wavelength in meters (m) f = frequency in waves per second (Hz, or s-1)

Example. What is the frequency of green light, which has a wavelength of 4.90 x 10- 7 m? Solution: s = wf; f =

s 3 x 10 8 m/s = = xxx s -1 -7 w 4.90 x 10 m

In addition to a scientific calculator, you will need a wavelength chart to answer these questions. 2. An X-ray has a wavelength of 1.15 x 10-10 m. What is its frequency?

3. What is the speed and wavelength of an electromagnetic wave that has a frequency of 7.8 x 106 Hz?

16


4. A popular radio station broadcasts with a frequency of 94.7 megahertz (MHz). What is the wavelength of the broadcast? (1 MHz = 1,000,000 Hz)

5. Cable television operates at a wavelength of about 1300 nanometers. Which wavelengths is this between in the Electromagnetic Spectrum?

6. Which is more dangerous, a radio wave or ultraviolet light?

7. The moon is 234,000 miles from earth. Light travels at 3 x 108 meters per second, and there are 1.62 kilometers in a mile. When you shine a flashlight on the moon, how long does it take for the light to hit the moon?

8. The smallest particle of light is the photon. Max Planck discovered that the energy of light can be calculated, where it is simply equal to a constant number multiplied by the frequency of the light: E = hf Where E is the energy of the light in joules h = Planckâ&#x20AC;&#x2122;s Constant = 6.626 x 10-34 joules .seconds f = the frequency of light in Hz (which is 1/seconds)

What is the energy of a photon of green light? (See question number 1)

9. What is the energy of a photon of light with a wavelength of 2 meters?

10. Since s = wf, and E = hf, can we calculate energy using wavelength, by combining the two formulas? Please show the combined formula. (Hint: note that f appears in both formulas).

17


Name____________________________ Period_______

WS5.2

The Bohr Model of the Atom Prior to the work of Niels Bohr, it was known that electrons existed outside of the nucleus, but beyond that very little was known. 1. What was the observation that Bohr based his research on?

2. The Balmer formula is : Solve this formula for n = 4.

w=

1 1   1 0.01097 2 − 2  n  2

3. The heart of Bohr’s discovery was that he was able to come up with real meaning to this formula. Draw a hydrogen atom with several energy levels (“shells”) around it and show electronic emission from the fourth shell to the second shell.

4. Draw diagrams indicating atomic emission and absorbance.

5. All of the visible atomic emissions for hydrogen enter the second energy level. What wavelength of light is emitted when an electron moves from the second energy level to the first energy level? What type of light is this?

18


Name:_______________________________________

Period:______

WS5.3

Electron Configuration (L1 only) Directions: Draw the electron configurations with orbital notation for each of the following atoms. Example: Here is the electron configuration of Sulfur with orbital notation. 16S:

1. Scandium:

1s2 2s2 2p2 3s2 3p4

2. Gallium:

3. Silver:

4. Krypton:

5. Iron:

6. Bromine:

7. Californium

8. Write the electron configuration using shorthand notation of the following elements: a. sodium

19


b. An oxygen anion, O-

c. Radon 9. Two substances that have the same number of electrons are isoelectronic. For example, both the fluorine anion F- and neon have ten electrons, they are isoelectronic. a. The bromine anion is isoelectronic with what uncharged element? b. Argon is isoelectronic with which monocation?

20


Name___________________________________ Period __________________

WS 5.4

Electron Configuration NOT! Worksheet (L1 only) In this unit we have seen how the electrons are organized around the nucleus. It is a very detailed view of the electrons location, and various rules to help keep it all straight have been devised, and are shown below.

Principles and rules of electron configuration

In each problem below, the electron configuration is incorrect. Fix it, and explain what law or principle (not Principal!) was violated. EXAMPLE: Law Violated: Aufbau Principle Fixed: 1. 1Hydrogen:

2s1

1s

Principle or rule Heisenberg

Bad

Good

Aufbau (build up) Hundâ&#x20AC;&#x2122;s Rule (spread out) Pauli (opp. spins)

1s22p1

1s22s1

(e-position uncertain)

1

1s22s22p2

1s22s22p2

1s2

1s2

Unit 5 electrons Dr. B.â&#x20AC;&#x2122;s ChemAdventure

Law Violated: __________ Fixed:

2. 17Chlorine

3. 39Yttrium (next page)

1s2

2s2

2p6

3s2

3p5

1s2

2s2

2p6

3s2

3p6

4s2

3d10

4p6

5s2

4d10

21


Law Violated: __________ Fixed:

Laws Violated: __________ Fixed:

4. 8Oxygen

1s2

2s2

2p4

5. 106Seaborgium

1s2

2s2

2p6

3s2

3p6

4s2

3d10

4p6

5s2

4d10

5p6

6s2

4f14

5d10

6p6

7s2

5f14

6d4

Law Violated: __________ Fixed:

22


Name:_______________________________________

Period:______

WS 5.5

Electron configuration and orbital notation self test Chemical behavior is determined by electron position. It’s a simple statement, but it says a lot. Another way of saying it is “Chemistry is all about where the electrons are”. That’s why we’ve been spending the last week focusing on electrons. However, somehow it always seems to bog down in some weird world of 1s2 2s2 2p6, and the Pauli Principle, and we forget our goal: if we know where the electrons are we know how the substance will behave. Why Neon is stable, and sodium is very unstable, and in fact why all the elements and the substances they form behave the way they do. Let’s pick an element. We know that oxygen contains ___ protons. And since it is not charged, it contains _____ electrons. We know that ____ of the electrons occupy the first shell, and the other six are in the second shell. We know that the first shell consists of a _____ orbital that holds _____ electrons, and so we say that the electron configuration of that first shell is 1s2. For the second shell we have six electrons, and we have learned that the first two will occupy a ____ orbital, and the next four go into ____ orbitals. Thus the electron configuration of oxygen is____________________. We can go into more detail, and show the exact orbitals that the electrons are in, which even show the direction the electrons are spinning in. An atomic orbital is simply a ______ of electrons, and the Pauli Principle tells us that electrons prefer to pair up with _________ spins. The first shell of oxygen contains one orbital, which we draw with a box like this:_______, showing that the electrons are paired up with opposite spins. The second shell begins with one more orbital for the two electrons of the 2s subshell, for a total of four electrons so far. We have ______ more electrons in oxygen, and they will occupy the three p orbitals. We remember to apply _________’s rule and spread these electrons out as far as possible in those three boxes. Thus we can draw the electron configuration of oxygen with its orbital notation right above it:

Note that this tells us that oxygen has four electrons in its outer (second) shell, and the two of them are unpaired….we also know from HONC that oxygen likes to form two bonds…a coincidence?? Let’s work out the electron configuration of nitrogen and see if we get three unpaired electrons: Nitrogen has _____ electrons, so the electron configuration with orbital notation is (be sure to spread out your p electrons): Does this orbital notation show 3 unpaired electrons?? If this makes sense, continue to the “how to ace it” guide.. If not, see me so we can do more examples. 23


How to ace the Electrons Exam

Howtoaceitunit5

In this Unit our goal was to determine where the electrons are in atoms. To find out, we performed two experiments that revealed the sharp lines that excited pure elements produced. We then analyzed this data from a historical perspective, beginning with the work of Niels Bohr. For this we needed to review the properties of light, including frequency, wavelength, energy, and, common types. This involved the use of the speed of light equation (s = wf) and an understanding of the electromagnetic spectrum. We then showed how the key mathematical solutions of Balmer and Rydberg allowed Bohr to put it all together to postulate energy levels, where atomic emission explains light, and produces the spectral lines observed for all elements. This was followed by a detailed look at the electron around the nucleus. We found that not only do electrons reside in shells, there are also subshells or orbitals within each shell. We observed how they spread out within an orbital (Hundâ&#x20AC;&#x2122;s Rule), and even how they spin when near each other (the Pauli Principle). We learned the configurations of electrons for all elements following the Aufbau Order, and how to write it all down by electron position, configuration, or orbital notation. This can rapidly tell us how many electrons are in each shell and subshell, the spin of each electron, and the number of unpaired electrons. The limits of observation of the electron are a result of the Heisenberg Uncertainty Princliple, which states that it is impossible to measure the position and velocity of an electron simultaneously, due to the extreme sensitivity of the electron. Finally, we showed how valence is easy to determine using the periodic table, and that valence may be drawn using electron dot formulas, also known as Lewis Dot Formulas. During this study we found that the periodic table is well designed to show the number of valence electrons for any element. In our next unit we will apply this to our understanding of the periodic table. To dominate this test, review all of the material in his packet: The lessons, the labs, and the worksheets. Here is some of the key information you should know: To ace this exam you should know:

24


1. Draw the symbols for Democritus, Aristotle, Paracelsus, Lavoisier, Dalton, Thomson, Rutherford, and Bohr 2. What is the significance of each symbol? Try to assign one or two key words for each symbol. 3. What are the dangerous wavelengths of light? 4. How does light relate to electrons? 5. What is wavelength? Units? 6. What is frequency? Units? 7. Rearrange the speed of light equation to show what frequency is equal to. 8. The electromagnetic spectrum: what is it? 9. Frequency: how does it relate to energy and safety? 10. Wavelength- how does it relate to frequency? 11. Energy: which rays have the highest energy? 12. Safety: why are radio waves generally considered safe? 13. Types of radiation Really long waves include ___________ and _______________; really short waves include __________ and ____________. The ___________________ (long/short) waves are dangerous. 14. Convert 452 nanometers to meters (107 nm = 1m) 15. Use s = wf to find the frequency of 452 nm light. 16. (Level one only) The Balmer formula. Find it in your notes: 17. Significance 18. Solve for the n= 3 to n = 2 transition: 19. Atomic Emission Spectra: How did we observe it? 20. Emission vs. absorbance- what is the difference? 21. The Bohr model of the atom- draw a model 21.5 What is the difference between electron configuration, and orbital notation?

25


22. Electron names to zirconium. For example, manganese has the symbol ____ 23. L1 only: Electron configurations- all elements…do iodine using noble gas notation. 24. L1 only: Orbital notation: all elements. Do silicon. Include the number of valence electrons, and the number of unpaired electrons. 25. The Heisenberg Uncertainty Principle. State what it is and why briefly. 26. L1 only: Orbitals: s, p, d, and f…how many electrons for each? How many orbitals for each? 27. L1 only: Aufbau principle. Give an example where it is broken, and fix it.

28. L1 only: Pauli exclusion principle. Break it and fix it.

29. L1 only: Hund’s Rule. Break it and fix it.

30. Lewis Dot Structures. Draw oxygen, for example

31. Valence Electrons. Do each column in the periodic table..

32. Why is it important to use scientific references, rather than websites, when writing a scientific paper?

33. Where are the electrons in an atom?

26


The Periodic Table Unit 6 What is the periodic table good for?

Introduction

The universe is composed of approximately 120 elements. These are pure substances with a fixed number of protons: hydrogen has 1, helium 2, carbon 6 etc.

They could be listed in a few rows:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120

But that wouldn’t really tell us much. Or maybe they could be organized another way, since for example 5 x 4 x 3 x2 x 1 = 120… but would there be a reason for organizing it that way? If the universe only has about 120 elements, it seems reasonable to expect some sort of organization to them. That is what the periodic table is about: trying to figure out how the most basic matter in the universe is organized. But there’s a problem. The periodic table just doesn’t look right. Here it is below: An important concept in science is known as Occam’s Razor, which suggests that the simplest

answer tends to be the right one.

In the table on the left most rows and columns are of different length, and it is in two pieces. This is

1


not a simple table. Could it be that we humans just havenâ&#x20AC;&#x2122;t figured it out yet? Iâ&#x20AC;&#x2122;m hoping you can do better. Somebody should. 1s2

A Basic Idea for the Organization of Matter.

2s2 2p6

We learned in our last unit that the periodic table is organized based on electron configuration. A good idea. But

3s2 3p6

3d10

4p6 4d10

4f14

consider this:

4s2 5p6 5d10

5f14 5g18

On the right is an organizational layout of the periodic table

5s2 6s2 6p6 6d10

6f14 6g18

7s2 7p6

7d10 7f14

8s2 8p6

8d10

9s2 9p6

10s2

based only on electronic configuration, that looks much more symmetrical. Notice how it closely it resembles a triangle. Is this a better scheme for the elements? This basic design may be a fundamentally better way of creating a more symmetical and revealing periodic table. A periodic table based on this idea is shown on the following page. Other more creative periodic tables have been created, including spiral designs like the one below (my favorite).

While we look at how the elements are organized, give some thought to your own organizational scheme. Me, being German, I am looking for major organization and balance. Maybe your are comfortable with a more abstract pattern to the universe, like the one I found on the web shown at the bottom:

2


Keep your mind open to your own pattern to the elements as we study them, and keep in mind that nobody has yet created the perfect periodic tableâ&#x20AC;Śit is still a mystery waiting to be solved. - In our lab activity you will create your own pattern.

3


Name_______________________________ Period_________

lab6.1

Instructions: Please read this and answer the 8 questions within it as you go.

What is everything made out ofâ&#x20AC;Ś on Planet Kalamata? Imagine that you are the scientific expert traveling to a far away planet, and everything seemsâ&#x20AC;Ś.different. You are asked to find our what everything is made out of. How would you do it? This is the goal of the Kalamata Science Expedition Project you are about to begin. You will be given progressively more data on all the weird matter on Planet Kalamata, and you need to arrange things so that some sense can be made out of it. Fortunately for you, this has already been done on another planet: Earth. The quest for a systematic arrangement of the elements on our home planet started with the discovery of individual elements. By 1860 about 60 elements were known and a method was needed for organization. In fact many scientists made significant contributions that eventually enabled Mendeleev to construct his table. The periodic table did not end with Mendeleev but continued to take shape for the next 75 years. There is definitely still room for improvement. Use the information above to help answer the following question. 1. If you traveled to a foreign planet and were asked to find out what everything is made out of, what would you do first?

4


The development of the Periodic Table on Planet Earth. By 1860 about 60 elements were discovered, with some basic data on them- not much more than their masses. Using this data alone, some patterns were discovered.

The development of the periodic table begins with German chemist Johann Dobereiner (1780-1849) who grouped elements based on similarities. Calcium (atomic weight 40), strontium (atomic weight 88), and barium (atomic weight 137) possess similar chemical prepares. Dobereiner noticed the atomic weight of strontium fell midway between the weights of calcium and barium: Ca Sr Ba (40 + 137) รท 2 = 88 40 88 137 Was this merely a coincidence or did some pattern to the arrangement of the elements exist? Dobereiner noticed the same pattern for the alkali metal triad (Li/Na/K) and the halogen triad (Cl/Br/I). Li Na K Cl Br I 7 23 39 35 80 127 In 1829 Dobereiner proposed the Law of Triads: Middle element in the triad had atomic weight that was the average of the other two members. Soon other scientists found chemical relationships extended beyond triads. Fluorine was added to Cl/Br/I group; sulfur, oxygen, selenium and tellurium were grouped into a family; nitrogen, phosphorus, arsenic, antimony, and bismuth were classified as another group.

2. What was it that Dobereiner noticed about the masses of elements that he thought was interesting? Please use your own words to describe this.

3. Did Dobereiner arrange the triads into columns, or rows? ___________ Why do you suppose he did that?

5


The First Periodic Table It was a 19th century geologist who first recognized periodicity in the physical properties of the elements. Alexandre Beguyer de Chancourtois (1820-1886), professor of geology at the School of Mines in Paris, published in 1862 a list of all the known elements. The list was constructed as a helical graph wrapped around a cylinder-elements with similar properties occupied positions on the same vertical line of cylinder (the list also included some ions and compounds). Using geological terms and published without the diagram, de Chancourtois ideas were completely ignored until the work of Mendeleev. 3. Try to draw the shape, and include some elements, for the periodic table that de Chancourtois created:

Law of Octaves

4.

English chemist John Newlands (1837-1898), having arranged the 62 known elements in order of increasing atomic weights, noted that after interval of eight elements similar physical/chemical properties reappeared. This was huge. Newlands was the first to formulate the concept of periodicity in the properties of the chemical elements. In 1863 he wrote a paper proposing the Law of Octaves: Elements exhibit similar behavior to the eighth element following it in the table.

Look at Newlands Columns. Compare to our known periodic table. Based on this, Newlands a. Had a great idea and his columns are identical to the modern periodic table b. Had a great idea and his columns are very close to the modern periodic table c. Had an great idea but his columns bear little resemblance to the modern periodic table.

6


Mendeleev's Periodic Table Then in 1869, Russian chemist Dimitri Mendeleev (1834-1907) proposed arranging elements by atomic weights and properties (Lothar Meyer independently reached similar conclusion but published his results after Mendeleev). Mendeleev's periodic table of 1869 contained 17 columns with two partial periods of seven elements each (Li-F & Na-Cl) followed by two nearly complete periods (K-Br & Rb-I). In 1871 Mendeleev revised the 17-group table with eight columns (the eighth group consisted of transition elements). This table exhibited similarities not only in small units such as the triads, but showed similarities in an entire network of vertical, horizontal, and diagonal relationships. The table contained gaps but Mendeleev predicted the discovery of new elements. In 1906, Mendeleev came within one vote of receiving the Nobel Prize in chemistry.

5. Look at Mendeleevâ&#x20AC;&#x2122;s Columns. Compare to our known periodic table. Based on this, Mendeleevâ&#x20AC;&#x2122;s columns a. are identical to the modern periodic table b. are very close to the modern periodic table c. bear little resemblance to the modern periodic table.

7


Noble Gases Lord Rayleigh (1842-1919) and William Ramsey (1852-1916) greatly enhanced the periodic table by discovering the "inert gases." In 1895 Rayleigh reported the discovery of a new gaseous element named argon. This element was chemically inert and did not fit any of the known periodic groups. Ramsey followed by discovering the remainder of the inert gases and positioning them in the periodic table. So by 1900, the periodic table was taking shape with elements were arranged by atomic weight. For example, 16g oxygen reacts with 40g calcium, 88g strontium, or 137g barium. If oxygen used as the reference, then Ca/Sr/Ba assigned atomic weights of 40, 88, and 137 respectively. Rayleigh (physics) and Ramsey (chemistry) were awarded Nobel prizes in 1904. The first inert gas compound was made in 1962 (xenon tetrafluoride) and numerous compounds have followed (see xenon compounds)--today the group is more appropriately called the noble gases.

Moseley's Periodic Law

Soon after Rutherford's landmark experiment of discovering the proton in 1911, Henry Moseley (18871915) subjected known elements to x-rays. He was able to derive the relationship between x-ray frequency and number of protons. When Moseley arranged the elements according to increasing atomic numbers and not atomic masses, some of the inconsistencies associated with Mendeleev's table were eliminated. The modern periodic table is based on Moseley's Periodic Law (atomic numbers). At age 28, Moseley was killed in action during World War I and as a direct result Britain adopted the policy of exempting scientists from fighting in wars. Shown below is a periodic table from 1930:

6. Circle any of Moselyâ&#x20AC;&#x2122;s columns that are identical with the current periodic table.

8


The Modern Periodic Table

The last major change to the periodic table resulted from Glenn Seaborg's work in the middle of the 20th century. Starting with plutonium in 1940, Seaborg discovered transuranium elements 94 to 102 and reconfigured the periodic table by placing the lanthanide/actinide series at the bottom of the table. In 1951 Seaborg was awarded the Nobel Prize in chemistry and element 106 was later named seaborgium (Sg) in his honor. 7. Note the atomic numbers of the lanthanides and actinides- these are the bottom two rows of the modern periodic table. Find where those numbers are missing on the periodic table. Mark that spot on the outline of the periodic table above. Now, draw what the periodic table would look like if these were properly inserted in the table, rather than dumping them down on the bottom:

8. Create a new element based on you. Include the symbol and name in the box.

Attention: New Addition to Periodic Table Name: Symbol:

Physical properties: Chemical properties: Usage:

Caution: Next, you will use what you have learned about the development of our Periodic Table of Elements on Planet Earth to create a Periodic Table of Elements on Planet Kalamata.

9


The Urban Chemical Consultant Company

From: The Planet Kalamata Science Expedition Date of Transmission: Nov 12, 2008 Earth Time Dear Consultants:

The scientists in our expedition are having some difficulty arranging the elements we have been studying according to their properties. We have heard that you on Earth are experts at this. Since we have had no luck perhaps you could help us. Following is all the information we have gathered so far. Your goal is to cut up these sheets and try to sort the elements into groups and then use them to create an organized table.

At this point we have only melting point, state (solid, liquid, and gas), and size (atomic radius). We hope to have atomic mass data soon.

Sincerely, The Kalamata Science Expedition Team

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φPhi

Tau Melting point (OB): -101 State: gas Atomic Radius (qm): 0.99

Upsilon Melting point (OB): -259 State: gas Atomic Radius (qm): 0.053

Melting point (OB): -218 State: gas Atomic Radius (qm): 0.066

ςChi

ΦPsi

ΩOmega

O

Melting point ( B): 817 State: solid Atomic Radius (qm): 0.125

Melting point ( B): -7 State: liquid Atomic Radius (qm): 0.111

Melting point (OB): 181 State: solid Atomic Radius (qm): 0.152

Alpha Melting point (OB): 3,550 State: solid Atomic Radius (qm): 0.077

Beta Melting point (OB): -189 State: gas Atomic Radius (qm): 0.191

Gamma Melting point (OB): -220 State: gas Atomic Radius (qm): 0.072

Delta Melting point (OB): 217 State: solid Atomic Radius (qm): 0.114

Epsilon Melting point (OB): 1410 State: solid Atomic Radius (qm): 0.117

Zeta Melting point (OB): 1,278 State: solid Atomic Radius (qm): 0.111

ΦEta

Melting point ( B): 64 State: solid Atomic Radius (qm): 0.227

ΦTheta

Melting point ( B): 113 State: solid Atomic Radius (qm): 0.104

Iota Melting point (OB): -249 State: gas Atomic Radius (qm): 0.160

Kappa Melting point (OB): 98 State: solid Atomic Radius (qm): 0.192

Lambda Melting point (OB): 660 State: solid Atomic Radius (qm): 0.143

Mu Melting point (OB): 30 State: solid Atomic Radius (qm): 0.122

Nu Melting point (OB): 2,079 State: solid Atomic Radius (qm): 0.083

Xi Melting point (OB): 839 State: solid Atomic Radius (qm): 0.197

Omicron Melting point (OB): -272 State: gas Atomic Radius (qm): 0.122

Pi Melting point (OB): 649 State: solid Atomic Radius (qm): 0.160

Rho Melting point (OB): 44 State: solid Atomic Radius (qm): 0.115

Sigma Melting point (OB): -210 State: gas Atomic Radius (qm): 0.070

O

O

O

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The Urban Chemical Consultant Company From: The Planet Kalamata Science Expedition Date of Transmission: November 14, 2008 Earth Time Further developments! We have just completed an analysis of the atomic mass of each one of our elements This information is listed below. We suggest that you add it to your element cards and make any needed adjustments in your group arrangements. Mass in trams Alpha 48.04 Beta 159.79 Gamma 75.99 Epsilon 112.34 Zeta 36.04 Eta 156.39 Upsilon 4.00 Psi 319.62 Theta 128.24 Iota 80.72 Kappa 91.96 Lambda 107.92 Mu 278.95 Nu 43.24 Phi 63.99 Omega 27.50 Xi 160.32 Omicron 16.00 Pi 97.22 Rho 123.88 Sigma 56.03 Tau 141.81 Chi 299.69 Delta 315.84

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The Urban Chemical Consultant Company From: The Planet Kalamata Science Expedition Date of Transmission: Nov 19, 2008 Earth Time

Dear Consultants: We have been working diligently to provide you more information about our elements. We have tried reacting each of our elements with the element Tau, and have determined the following ratios between each element and tau. Element Alpha Beta Gamma Delta Epsilon Zeta Eta Theta Iota Kappa Lambda Mu

Reacting Ratio Element: Tau 1:4 ----1:2 1:4 1:2 1:1 1:2 --1:1 1:3 1:3

Element Nu Xi Omicron Pi Rho Sigma Tau Upsilon Phi Chi Psi Omega

Reacting Ratio Element: Tau 1:3 1:2 --1:2 1:3 1:3 --1:1 1:2 1:3 --1:1

We suggest that you add this information to each of the element cards that we already sent. Then consider this information regarding your proposed groupings. Make whatever changes are needed to your groupings. We will continue to work with our elements and will fax you when we have some significant information.

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The Urban Chemical Consultant Company From: The Planet Kalamata Science Expedition Date of Transmission: November 23, 2008 Earth Time Further developments! After many experiments, the Kalamatian scientists have determined the oxidation state of each one of their elements. This information is listed below. We suggest that you add it to your element cards and make any needed adjustments in your group arrangements. We have adjusted our oxidation data so it is consistent with earth data. For example, element Alpha loses 4 fetas to form a +4 oxidation state, and Gamma gains one feta to form a -1 oxidation state. Element

Oxidation State

Element

Oxidation State

Element

Alpha Beta Gamma Epsilon Zeta Eta Upsilon Psi

+4 0 -1 +4 +2 +1 +1 -2

Theta Iota Kappa Lambda Mu Nu Phi Omega

-2 0 +1 +3 +3 +3 -2 +1

Xi Omicron Pi Rho Sigma Tau Chi Delta

Oxidation State +2 0 +2 -3 -3 -1 -3 -2

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The Urban Chemical Consultant Company From: The Planet Kalamata Science Expedition Date of Transmission: November 27, 2008 Earth Time Here is the final transmission from the Kalamatians. They have a major breakthrough. They have been able to analyze the nucleus and have discovered a subatomic particle called the vega. The number of vegas present in the nucleus of the atom of each element are listed below. Add it to your element cards and make further adjustments in your group arrangements. Element

Alpha Beta Gamma Delta Epsilon Zeta Eta Theta

Number of Vegas in the nucleus 24 72 36 136 56 16 76 64

Element

Iota Kappa Lambda Mu Nu Xi Omicron Pi

Number of Vegas in the nucleus 40 44 52 124 20 80 8 48

Element

Rho Sigma Tau Upsilon Phi Chi Psi Omega

Number of Vegas in the nucleus 60 28 68 4 32 132 140 12

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Kalamata Project Assessment Sheet Attribute

Points Possible

Original cards submitted with all information added Table submitted with three dimensional arrangement Table is color coded Table is attractively decorated An explanation of the horizontal alignment is present and is based on scientific fact An explanation of the vertical alignment is present and is based on scientific fact An explanation of the 3rd dimensional alignment is present and is based on scientific fact Explanations are combined into a KEY Table is sturdy A comparison of this table to the class periodic table is included and includes 5 points The prediction for element X are reasonable and are filled in on below. This sheet is completed by the team and is filled in. Total Points

10 20 10 5 5

Points assigned by team

Points assigned by CEO

5 5 5 5 10 10 10 100

Predictions for Element X The Kalamatians have reason to believe that another element, call it X, exists somewhere between Mu and Chi. They have requested that you use your element arrangement to predict the following properties of this unknown element X. Element X Melting Point:_______ State:________ Atomic Radius:________ Reacting Ratio, Element X:Tau_________ Atomic Mass:________ Oxidation State:_________ Number of Vegas in the nucleus:_______

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19


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Name___________________________________ Period_______

lab 6.2

Three-Dimensional Periodic Tables lab6.1

30 points Elements are not two-dimensional, so why should the periodic table be? In the introduction to this unit, you saw several unusual versions of the periodic table. Your goal for this project is to create a useful three-dimensional version of the periodic table. The design is up to you. An example of a 3D periodic table with rotating parts will be displayed to help get you started. Work in groups of 1 or 2. An incredible resource is available within meta-synthesis.com. The best way to get there is to google “periodic table formulations” and click on the first hit, which should be: http://www.metasynthesis.com/webbook/35_pt/pt.html . You’’ find more periodic table design ideas than you can shake a stick at. Here is the schedule for the project: Homework for Day 1: Bring in printouts of your favorite 3-D periodic tables you found on the web, and materials to make it happen. Be creative! Materials can include cardboard, clay, wood, legos, boxes, marbles, pennies, etc. You are only limited by your imagination. Your work can be based on things you found on the web, but must have original contributions to it. Note that any idea that includes functional lighting (for example using christmas lights) will receive 5 bonus points. Day 1 in-class: Using equipment you have brought in, and anything available in the lab, begin construction of your 3D periodic table. You will have two class periods to complete your table. Homework for day 2: Bring in more material for yourself and for others.

Day 2: Complete your 3D periodic table, and hang it or post it on the wall, or place it on a table. Homework: Prepare an informative presentation on your periodic table, that must include a handout. Day 3: Present your 3D periodic table. Your score will be based on 1. 10 points: Functionality: the added dimension (and lights, if you use them) serves a useful purpose 2. 10 points: Creativity: The design is unique and shows imagination without sacrificing utility. 3. 10 points: Timeliness: The project is finished on time; each daily task is completed on schedule. 21


To help you get started some ideas are shown on the following page: 3-D Periodic Table Idea Generator 1. Here is the periodic table in the shape of a box, and a pyramid

A sphere, an elephant, cylinders

A spiral, more cylinders:

Use these ideas to create your own original 3D periodic tables. If you prefer, you can also create a histogram that shows a conventional periodic table where some property of each atom is compared; some examples are shown on the first powerpoint slide of this unit. Have fun, while at the same time trying to create something that is not only coo-looking, but is also useful.

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Name: ______________________________________

Period: _____

WS6.1

Periodic Table WS I: History and organization 1. List three elements that were known for over 2000 years

2. Lavoisier was the first major contributor to the periodic table. What was his contribution?

3. What was the big breakthrough that led to the discovery of nearly 50 more elements, and who is credited with the discovery?

4. Around when did this take place?

5. What did John Newlands get right, and what did he get wrong?

6. What three elements did Mendeleev predict?

7. The least reactive group in the periodic table is the __________ __________ 8. Which group of metals desperately wants to lose an electron?

9. Which group easily loses 2 electrons?

10. This is the first element in the d-block.

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Name: ___________________________________Period: _____

WS6.2

Periodic Table WS II: Groups, periods, and reactivity 1. List three alkali metals 2. List two alkaline earth metals 3. What key feature do the families (also known as columns or groups) of the periodic table have in common?

4. How many valence electrons do the halogens have? 5. True or false: The noble gases are grouped together because of their high reactivity. 6. True or false: The noble gases all have 8 valence electrons.

7. Columns in the periodic table are known as __________ or _____________; rows are called _____________. 8. Write the ionic compounds that would form when the following elements combine: Example: Sodium and chlorine: NaCl Lithium and bromine:__________ Potassium and Iodine__________ Fluorine and Lithium___________ Beryllium and chlorine__________ Magnesium and oxygen____

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Name: ____________________________________Period: _____

WS6.3

Using Periodic Trends to Predict Atomic Radius Directions: Using the trends discussed in class, answer each of the following questions as â&#x20AC;&#x153;logicallyâ&#x20AC;? as possible.

1. Which of the following kinds of atoms has the largest atomic radius? 31Gallium

11Sodium

19Potassium

2. Which of the previous kinds of atoms had the smallest atomic radius?

3. Rank the following three kinds of atoms by increasing atomic radius, highest = 1. 76Platinum

79Gold

47Silver

4. Rank the following three kinds of atoms by increasing atomic radius, highest = 1. 15Phosphorus

17Chlorine

35Bromine

5. Which of the following kinds of atoms has the largest atomic radius? 21Scandium

22Titanium

30Zinc

6. Which of the atoms in question 6 had the smallest atomic mass?

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Name: ______________________________________

Date: ______

WS6.4 Period: _____

Using Periodic Trends to Predict Electronegativity Directions: Using the trends discussed in class, answer each of the following questions as â&#x20AC;&#x153;logicallyâ&#x20AC;? as possible. 0. What is electronegativity? 1. Which of the following kinds of atoms has greatest Electronegativity? 3Lithium

(Li)

11Sodium

(Na)

19Potassium

(K)

2. Which of the previous kinds of atoms had the lowest Electronegativity?

3. Rank the elements from highest (1) to lowest (3) electronegativity. 13Aluminum

14Silicon

17Chlorine

4. Rank the elements from highest (1) to lowest (3) electronegativity.. 34Selenium

17Chlorine

9Fluorine

5. Which of the following kinds of atoms has the greatest Electronegativity? 35Bromine

20Calcium

12Magnesium

6. Which of the atoms in the previous question had the lowest Electronegativity?

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Name: ______________________________________

Date: ______

WS6.5 Period: _____

Using Periodic Trends to Predict Ionization Energy

1. Which of the following kinds of atoms has highest Ionization Energy?

3Lithium

19Potassium

37Rubidium

2. Which of the previous kinds of atoms had the lowest Ionization Energy?

3. Rank the following three kinds of atoms by increasing Ionization Energy. 9Fluorine

16Sulfur

17Chlorine

4. Rank the following three kinds of atoms by increasing Ionization Energy. 3Lithium

5Boron

6Carbon

5. Which of the following kinds of atoms has the greatest Ionization Energy? 7Nitrogen

15Phosphorus

51Antimony

6. Which of the previous kinds of atoms had the lowest Ionization Energy?

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Name: ______________________________________

Date: ______

WS6.6 Period: _____

Using Periodic Trends to Predict Elemental Properties

1. Which of the following kinds of atoms has highest Ionization Energy? Fluorine (F) Francium (Fr) Cesium (Cs) 2. Which element wants electrons the most? Or, said another way, which element has the highest electronegativity? Oxygen (O) Sulfur (S) Selenium (Se) 3. Rank the following three kinds of atoms by increasing Ionization Energy: 1 = highest, 3 = lowest Fluorine (F) Sulfur (S) Chlorine (Cl) 4. Rank the following three kinds of atoms by increasing Ionization Energy. Lithium (Li) Sodium (Na) Potassium (K) 5. Which of the following kinds of atoms has the lowest Ionization Energy? Nitrogen (N) Oxygen (O) Carbon (C) 6. Which of the previous kinds of atoms had the lowest Ionization Energy? Cesium (Cs) Iron (Fe) Fluorine (F) 7. Which ionic compound has the highest melting point Cesium chloride (CsCl) cesium fluoride (CsF) cesium iodide (CsI) 8. Describe what electronegativity is using your own words.

9. Describe what atomic radius is using your own words.

10. Describe what ionic radius is using your own words.

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How to Ace the Periodic Table Quiz

Howtoaceunit6

To ace this quiz, review your notes, the Periodic Table PowerPoint, the worksheets, and the labs completed. Then, try the questions in this guide. Get help on anything you don’t understand, and finally, sleep well knowing you are in good shape. Know the history of the periodic table 1. List 3 elements known before 1790 2. Lavoisier: What was his contribution 3. Poor John Newlands: what did he get right, wrong 4. Mendeleev: Why is he “the father of the periodic table”? 5. Groups or families are ____________ 6. Periods are _________ 7. Metals, nonmetals, and metalloids: Where is the dividing line? Groups: For each below know where they are, ions formed, and why 8. Alkali metals 9. Alkaline Earth Metals 10. Halogens 11. Noble Gases 12. S,p,d, and F blocks- where they are, how many electrons in each 13. Lanthanides are the ____ column in the ___ block 14. Actinides are the ____ column in the ___ block 15. Valence electrons- know for each family 16.Know the number of valence electrons for charged and uncharged atoms. And be sure to know what elements the charged atoms are isoelectronic with. For example, Sc3+ is isolectronic with _______ The 4 Trends: 17. Atomic and ionic radii. Largest element/ion is___; Arrange Ca, Cs, Sr 18. Electronegativity and ionization energy: Highest value is for the element _______. Arrange Cl, Se, Te 16. Know how to draw simple ionic compounds based on charge. For example sodium chloride = NaCl 17.Magnesium chloride, potassium oxide 18. Aluminum fluoride, lithium sulfide 19. Be sure to know the names of elements 1-40. 20. Describe a useful 3D periodic table 21. What is the periodic table good for?

Answer

Be prepared to give a one paragraph answer Be prepared to give a one page answer. 29


30


Unit 7: Bonding

How do atoms bond together?

Introduction If we mix together sodium and chlorine, an explosion occurs. When it’s over we see a white powder: table salt. What is happening and why? Neon, on the other hand, never reacts with anything. Why is that? Hopefully you are thinking about electrons, particularly valence (outer shell) electrons, when pondering these questions. And maybe this is helping you understand what is going on in some of these cases. But it may not be as simple as you think…for example, when iron rusts, it combines with oxygen, but at least two products are formed- FeO, and Fe2O3. What is iron doing, and why? All of these observations can be understood by taking a close look at the electrons around an atom., especially the outer layer. In this unit we will use what we know about the electron to understand how and why chemical bonds form. And the same basic principles will be used in the following unit to see how these bonds break and new ones form when chemical reactions occur. To understand a chemical bond is an immensely powerful tool. Eating, breathing…these are chemical processes, with bonds breaking and forming. Your iPod, cell phone, batteries, the engine in your car, everything around you is happening based on the atoms within these things and their inherent and predictable desire to give up, take, share, or transfer electrons. Even thought itself is based on electrons moving in neurons, assisted by neurochemicals in your brain. A powerful tool indeed. Schedule: Day 1: Intro to Bonding 1. Salts Lab 2. Introduction to Bonding 3. Homework: WS 7.1 = Identifying Bond Types Day 2: Ionic Bonding I 1. Begin Become a Millionaire Project 2. Ionic Bonding 3. Homework: WS 7.2 = Monatomic Ions Day 3: Ionic Bonding II 1. Complete Ionic Bonding 2. Homework: 7.3 Polyatomic and Polyvalent ions Day 4: Covalent Bonding 1. Make a Giant Molecule Project

2. Introduction to Covalent Bonding 3. Homework: WS 7.4 = Bond Formulas Day 5: Metallic Bonding 1. Complete Covalent Bonding 2. In-class: WS 7.5 = Bond Formulas and Isomers 3. Homework: WS 7.6 = Additional Problems Day 6: Review 1. In-class: Bonding Review Worksheet 2. How to Ace the Bonding test 3. Homework: Review Packet for Bonding Test Day 7: Bonding test. 1


Names___________________and_______________ Period__________

Lab7.1

Forming Ionic Compounds Introduction: Ionic compounds are everywhere. Sometimes simply called salts, we add them to food (sodium chloride), â&#x20AC;&#x153;enhanceâ&#x20AC;? our food (monosodium glutamate, or MSG), preserve our food (sodium benzoate), or we may even take a bath in them (magnesium sulfate, or Epsom salts.) In this lab our goals are to explore the physical and chemical behavior of ionic compounds. Are they reactive? Are they soluble in water? Can we predict the products of a reaction? Do the individual ions show trends in terms of solubility or color? Procedure: 1. We have about 12 different types of dissolved ionic compounds. Write their names on the list below. As a class we will discuss how we can as a group mix together as many combinations as possible. Our equipment includes salt solutions, spot plates, pipettes, and graph paper. Our plan:

2. We need to briefly report our results, and look for any patterns, including color changes or other signs of a chemical reaction. Our plan:

Hand in your graph paper, with the matrix on one side, and the answers to questions 2,3, and 4 on the other.

Write down the names and formulas of your starting solutions: Names Ionic Compound Names (sodium chloride, Ionic Formulas (NaCl, for example) for example)

2


Questions: 1. Write five examples of chemical reactions that produced precipitates. Use the words, not the formulas for now. Example: Sodium chloride + magnesium iodide ď&#x192;  sodium iodide + magnesium chloride L1 only: Write balanced chemical equations for each one. For the above reaction: 2 NaCl + MgI2 ď&#x192;  2 NaI + MgCl2 1. 2. 3. 4. 5.

2. Do you see any patterns for types of compounds which tend to precipitate, or remain in solution?? Look for a common ion that always leads to a precipitate. Cations that tend to form precipitates: Cations that tend to not form precipitates (these are soluble salts): Anions that tend to form precipitates: Anions that tend to not form precipitates (these are soluble salts):

3. Can we determine the colors of the ions based on these reactions? Look for patterns of color that must have come from a specific anion or cation. Cations and their likely color:

Anions and their likely color:

In our next lesson we will use this data to determine the nature of the ionic bond.

3


Name_________________________________ Period_________

Lab 7.2

Become a Millionaire Project Connecticutâ&#x20AC;&#x2122;s Biotechnology Companies Want to make a million dollars? This week is your chance. Well, at least on paper. How it works: One of the best places to make (or lose, especially now) serious money is in the stock market. You invest money in a company, and if the stock value of that company goes up, you make money. Example: You purchase 1000 dollars worth of Google stock. On the day you buy it each share is worth 485 dollars. One month later the stock is selling at 560 dollars per share- its value has increase by 15%. You have just made a quick 150 dollars on your investment. In other words,

stock value =

new price x investment original price

Each student is given one million dollars. Invest it in any two of the following Connecticut Biotechnology Companies: UPDATE: Beware- several of these companies are in their death throes as they are going out of businessâ&#x20AC;Śthey are likely to be incredibly bad investments. 1. Neurogen (NRGN) 2. Achillion (ACHN) 3. Curagen (CRGN) 4. Vion (VION) 5. Pfizer (PFE) 6. Bristol-Myers Squibb (BMY) 7. Bayer (BAY) 8. Alexion (ALXN) 9. Covidien (COV) 10. Hologic (HOLX) Sample calculation: You invest half a million dollars in Covidien and the stock increased from 20 to 21.

stock value =

new price x investment original price

= 21/20 x $500,000 = 525,000. You just made 25,000 dollars. Go buy a new car.

Research these companies tonight and choose your investments. For example, you may put $700,000 into Pfizer, and the rest ($300,000) into Covidien. All student will be responsible for knowing the basics of each company. On the following page is a chart for keeping track of your stocks 4


Become a millionaire project Chart

Name______________________________

Stock #1:______________ Investment: $_____________Original Price:____________ Stock #1:______________ Investment: $_____________Original Price:____________ Sample calculation: You invest half a million dollars in Covidien and the stock increased from 20 to 21. Current value = new price/ original price x investment = 21/20 x $500,000 = $525,000. You just made 25,000 dollars. Go buy a new car. Date

Stock #1:

Stock #1

Stock #2:

Stock

Total

I have made

_______

Current

_______

#2

Value

(+) or lost (-)

New Price

value

New Price

Current

Today

value

Today

this much:

Final Value: In this project I made/lost $______________

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8


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Name____________________________________Period___________Date_______ lab7.1 Make a Huge Molecule Project

20 Points

Introduction: Organic molecules have incredibly complex and varied structures. Simple plants can produce them naturally, yet it takes people literally years to make them in the lab. Shown below are some examples of complex, large natural products from plants. H OH

O

O

O

O

O

OH

O

H H

O

O

OH

OH

O

O O

O

HO

H

NH O

O

H O

O OH O O

H

O

O OO

O O azadirachtin

1. taxol (paclitaxel)

N

O

N

O

O

N

N O N Co N N

N 3+ N

O N

OH HO

N

O N

O O

P

O O

O

R

O O

O

OH H

OH

O

H

HO

O

N HO

O

OH

O H O

OH OH

O O

OH

H

H O

H

OH OH 4. ginsenoside rb2 OH

3. Vitamin B12

OH

13


If you were an organic chemist and attempted to synthesize any of these molecules, it would take you years, or you might never get there. Your task as a group is to assemble one of these molecules. We will take a picture of the final molecule once it is fully assembled. Some helpful suggestions: 1. Pick a molecule 2. Subdivide the molecule into pieces. 3 from each group of 4 should assemble a selected region of the project. Label key attachment points. The other member should write a paper about the molecule being synthesized; see #5. 3. Those not assembling should check the work as it progresses for accuracy. 4. Each station should combine their pieces, and one â&#x20AC;&#x153;finisherâ&#x20AC;? from each group should combine the pieces together to make the final molecule. 5. Each group of 4 must also submit a one page paper about the molecule being made. This must be an original document with reliable citations. You may want to have one member of each station work on that exclusively. This is in every way a group project. Your grade will be determined by the accuracy of the final molecular structure, and by your submitted paper. Scoring Guide: 1. Molecule is assembled correctly in two dimensions (10 points) 2. All stereochemistry connections are correct (3 points) 3. The finishers correctly combined each fragment (5 points) 4. The structure of the final molecule is correct (2 points) Good luck assembling your molecule!

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NEW!!: Ions

ionchart This table is designed to help you memorize the ions on your own: cover the lines below with a piece of paper as you work your way down. Cations Anions 1+ 1Group 1: Lithium Rubidium + Li Rb+ Sodium Cesium + Na Cs+ Potassium Francium K+ Fr+

Group 7: fluoride Fchloride Clbromide Br-

iodide I-

Polyatomic: Ammonium NH4+ Monatomic: Silver Ag+

2+ Group 2: Beryllium Strontium 2+ Be Sr2+ Magnesium Barium Mg2+ Ba2+ Calcium Radium 2+ Ca Ra2+

Zinc Zn2+

Polyatomic Nitrite hypochlorite NO2ClONitrate chlorite NO3 ClO2Bisulfate chlorate HSO4 ClO3Hydroxide perchlorate OHClO4Cyanide bromate CN BrO3permanganate iodate MnO4IO3Bicarbonate acetate HCO3 CH3CO22Polyatomic Carbonate CO32Sulfite Chromate 2SO3 CrO42Sulfate Dichromate 2SO4 Cr2O72-

Group 6 oxide O2sulfide S2-

Monatomic:

3+ Group 3 Boron B3+ Aluminum Al3+

Group 5 Nitride N3Phosphide P3-

3-

Polyatomic: phosphate PO43-

All other metal ions are polyvalent and must be specified; for example Cu(II) is Cu2+. 15


NEW: Ion Flash Cards: Use these to memorize the Ions in groups of two

ioncardsfront

Lithium

Beryllium

Boron

fluoride

permanganate

oxide

Sodium

Magnesium

Aluminum

bromide

bicarbonate

sulfide

Potassium

Calcium

Chloride

hypochlorite

Rubidium

Strontium

iodide

chlorite

Cesium

Barium

Francium

Radium

nitrite

perchlorate

carbonate

Ammonium

Zinc

nitrate

bromate

sulfite

nitride

bisulfate

iodate

sulfate

phosphide

hydroxide

acetate

silver

chromate

dichromate

chlorate

cyanide

phosphate

16


NEW: Ion Flash Cards: Use these to memorize the Ions in groups of two

CrO42-

ioncardsback

O2-

MnO4-

F-

B3+

Be2+

Li+

S2-

HCO3-

Br-

Al3+

Mg2+

Na+

ClO-

Cl-

Ca2+

K+

ClO2-

I-

Sr2+

Rb+

Ba2+

Cs+

Cr2O72-

ClO33-

CO32-

ClO4-

NO2-

Ra2+

Fr+

N3-

SO32-

BrO3-

NO3-

Zn2+

NH4+

P3-

SO42-

IO3-

HSO4-

CH3CO2-

OH-

PO43-

Ag+

CN-

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Name________________________ Period___________

WS 7.1

Types of Bonds Worksheet Chemical bonds, like people, exhibit varying degrees of selfishness. Some bonds are shared unequally- one element is giving an electron, and the other element is taking it. We call these Ionic Bonds. Others share a pair of electrons evenly- these are covalent bonds. They may be very evenly shared (â&#x20AC;&#x153;nonpolar covalent) if the nonmetals are identical or if the bond is carbon to hydrogen, or polarized (polar covalent) if the nonmetals are not the same. Perhaps the most â&#x20AC;&#x153;sharedâ&#x20AC;? electrons in bonding are the metallic bonds, which involve a mobile sea of electrons.

Fortunately, the periodic table can assist us greatly when it comes to identifying bonds. The key dividing point is the staircase- the dividing line between metals and nonmetals (remember that H is a non-metal). Here is a helpful key to identifying bond types Bond is between

Type of bond

Two metals

metallic

A metal and a non metal

Ionic

Two identical nonmetals, or C-H

Nonpolar covalent

Two different non metals

Polar covalent

Identify each bond as metallic (M), ionic (I), nonpolar covalent (NPC), or polar covalent (PC). Examples: C-C: NPC Na-F: I Na-Na: M

1. Na-Cl: ____

2. C-O: ____

7. Si-Br: ____

8. Ca-O : ____

3. Br-Br: ____

4. Au-O: ____

5. Na-I: ____

6. C-H: ____

9. Y-Y: ____

10. Ca-S: ____

11. Fe-Cl: ____ 12. H-H: ____

13. Point an arrow to each of the 13 bonds and identify it as I (ionic), M (metallic), PC (polar covalent), or NPC (non-polar covalent).

O

Br N

H O

O

Si F

Na

Li 18


Name________________________________Period___________

WS 7.2

Monatomic Ion Worksheet For simple ionic compounds, name = cation anion with an “ide” ending. Exanple: sodium fluoride Write the name and formula of the ionic compound formed from the combination of the given elements. Remember to use the “switch the charges” trick. If no bond forms write NB for “no bond” Example: chlorine and calcium Solution: Salts are named “cation anion-ide, like sodium chloride. From the periodic table we know that calcium is a +2 cation and chlorine is a -1 anion, so we know that the name of the salt will be Calcium Chloride. It may help to write the charges above the element symbols: +2 -1 Ca Cl We then switch the charges ( and remove the signs), giving us Ca1Cl2, which we can write the formula simply as CaCl2. Why this makes sense: Calcium needs to remove it’s extra 2 valence electrons to create a full outer shell, which makes it much more stable than uncharged calcium. Chlorine needs to gain one electron to fill it’s outer shell, so the extra electron from calcium is used for a second chlorine atom, and the opposite charges form two strong attractive ionic bonds: Cl-+Ca+-Cl, or Cl-Ca-Cl.

1. Sodium and chlorine: Name: ___________ Formula: 2. bromine and sodium: (remember to always put the cation first) Name___________________ Formula______________ 3. Magnesium and chlorine: Name___________________ Formula______________ 4. Sodium and sulfur:

Name___________________ Formula______________ 5. Sodium and phosphorus: Name___________________ Formula______________ 6. Bromine and fluorine: Name___________________ Formula______________ 7. Magnesium and oxygen: Name___________________ Formula______________ 19


8. Calcium and sulfur: Name___________________ Formula______________ 9. Sodium and fluorine: Name___________________ Formula______________ 10. Magnesium and phosphorus: Name___________________ Formula______________ 11. Barium and Nitrogen:

Name___________________ Formula______________ 12. Arsenic and Beryllium: Name___________________ Formula______________ 13. Magnesium and calcium: Name___________________ Formula______________

2. Correct the names or formulas if they are incorrect, using the first two problems as examples. If they need no changes write OK. 1. Chlorine sodium: Sodium chloride 2. NaCl2: NaCl 3. potassium chlorine:__________________ 4. K2Cl: __________ 5. Magnesium oxygenide: __________________ 6. Mg2S3: ________________ 7. K203: __________________ 8. N2Mg3: _____________ 9. Chlorine potassiumide__________________ 10. NaI: _________________

20


Name__________________________________ Period____________

ws7.3

Polyatomic and Polyvalent Ions Worksheet Not all salts are as simple as, say, table salt (NaCl). Some, like baking soda (NaHCO3), contain an ion which has more than one atom- it is polyatomic. In this case the bicarbonate anion HCO3- is polyatomic. A list of the common polyatomic ions is provided, and this worksheet will help you become familiar with them. The cations of the d and f-block, and a few from the p-block can form more than one ion- they are polyvalent. The group charges and polyvalent region of the periodic table is shown below. If you went to the 0 stockroom to get +1 +2 +3 -3 -2 -1 some copper chloride, you would find that there are 2 types: Copper (I) polyvalent chloride, and copper (II) chloride. In these cases, the charges are specified using roman numerals. Practice working with both of these types of salts by solving the problems below.

A. Using your Ion List in this packet, provide formulas for the following salts. Some of these are done for you- this will help show when you need to use parentheses: 1. Sodium cyanide: NaCN 2. ammonium chloride: NH4Cl 3. Ammonium carbonate (NH4)2CO3 4. Ammonium oxide:______________ 5. Lithium sulfate: _____________ 6. Potassium permanganate:________ 7. Magnesium sulfide:__________ 8. Magnesium phosphide:_________ 9. Rubidium bromate (a bromate is BrO3-):________________ 10. Sodium chlorite:_______________ B. Provide names for the following salts. Use the solved problems to guide you. 1. NaI: sodium iodide 2. CaCO3: calcium carbonate 3. K3PO4:___________________ 4. K2SO4:_____________________ 5. Ra3N2: ____________________ 6. AlP: ____________________ 7. BeI2: ___________________ 8. Mg(ClO3)2: _____________________________ 9. BeF2: _____________________ 10. Al2(CO3)3: ____________________________

21


C. Fix any names or formulas below that are incorrect: 1. sodium dichloride: sodium chloride 2. CaCl: CaCl2 3. potassium dioxide: _______________ 4. Al3O2: ____________________ 5. Disodium sulfate: ___________________ 6. Mg2CO3: ________________________ 7. NH4O: ______________ 8. (NH4)3P:_______________ D. Provide formulas for the following salts: 1. Titanium (IV) chloride: TiCl4 2. Iron (III) dichromate: Fe2(Cr2O7)3 3. Silver chloride: _____________. 4. Yttrium (III) chloride: __________________ 5. Platinum (II) oxide: ________________ 6. Iron (II) sulfate:__________________ 7. Osmium (IV) sulfate:_______________ 8. Cobalt (VI) chloride:___________________ E. Provide names for the following salts. Only use roman numerals for polyvalent cations. 1. FeO: Iron (II) oxide 2. Fe2O3: Iron (III) oxide 3. Pd2CO3: ___________________ 4. AgCl: _____________________ 5. NaCl: Sodium chloride 6. CaO: _______________ 7. K2O: _________________ 8. NH4Cl: ______________________ 9. AlPO4: _________________ 10. CuS: __________________. F. Indicate if these are correct, and fix any that are wrong: 1. Scandium (II) chloride is ScCl3: ____________________________________ 2. CaCl2 is calcium (II) chloride: _____________________________________ 3. NiPO4 is nickel (III) phosphite: __________________________________ 4. BaI2 is barium (II) iodide: _______________________________________ 5. NaI is sodium iodide: ________________________________

22


Name_____________________________ Period__________________

ws7.4

HBrONClIF Worksheet One of the most common sources of confusion in a first year chemistry course concerns diatomic molecules. These are the elements that prefer to bond to themselves in their pure elemental state. The diatomic elements include hydrogen, bromine, oxygen, nitrogen, chlorine, and fluorineâ&#x20AC;Ś.hence the mnemonic HBrONClIF. The two most common errors are that 1. Students sometimes forget to write these elements as diatomic molecules. The oxygen you are breathing does not have a molecular formula of O, it is O2 (think HBrONClIF) 2. Students assume that if these elements are part of a molecule, they must still be in pairs. Not true. For example, water is H2O, not H2O2. Chloroform is CHCl3, not CHCl2.

Example: Correct the formulas for the following substances when necessary Formula O I C B Br N Cu Fixed O2 I2 (ok) (ok) Br2 N2 (ok) 1. Correct the formulas for the following substances when necessary Formula O Fe In Ru I F Fixed

Al (ok)

F F2

F

H

Ar

2. Write formulas for the following elements and molecules. The names provide hints. a. water: f. carbon monoxide b. Carbon dioxide g. Bromine c. Carbon tetrachloride e. Iodine d. Fluorine f. gallium e. Nitrogen 3. Why is chlorine diatomic? Draw a Lewis dot structure and two circles to show how each chlorine can assume a noble gas configuration by sharing a pair of electrons. Label the bonding electrons as well as the nonbonding lone pairs of electrons..

23


Name: ______________________________________

Date: _____

WS7.5

Covalent Bonding Worksheet #1: Bond Formulas Guide: We humans are loaded with covalently bonded molecules. How are these molecules bonded together? To find the number of bonds in an element, use the number of valence electrons to draw the electron dot structure. Paired electrons form non-bonding lone pairs of electrons, and unpaired electrons each form a bond. 1. Complete the table below to help guide you in bond formations below. A few are done to assist you: Element Valence electrons Lone pairs Bonds H 1 0 1 P 5 1 3 Cl O Si 2. Use this information to draw the molecules, including bonds and lone pairs of electrons. Again, some are done to assist you a. H2O

H-O-H

b. N2

N

c. CO2

d. NH3

N

e. CS2

f. CHCl3

g. H2S

h. C2H5Cl

i. NHO

j. SiCBr6

k. C2HF

l. COS

m. H2O2

n. CH2O

o. SiNCl

p. O3

Cl

Si N

24


Name: ______________________________________

Date: ______

Period:

WS7.6

Covalent Bonding Worksheet #2: Bond Formulas and Isomers Directions: For each of the molecular formulas given, draw all possible isomers in bond formula notation, using the example below as a guide: H

Example: C2H7N (2 isomers possible):

H N C H H C H H H

and

H H C H N H C H H H

1. H2O (1 isomer possible

6. CF4 (1 isomer possible)

2. C3H6 (2 isomers possible)

7. C2H5Cl (1 isomer possible)

3. CH4O (1 isomer possible)

8. NF3 (1 isomer possible)

4. N2H4 (1 isomer possible)

9. C3H7F (2 isomers possible)

5. C2H6O (2 isomers possible)

10. ____ (2 isomers possible)

25


Name________________________ Period______________

WS7.7

Covalent Bonding Worksheet 3: Additional problems. 1. Use Lewis structures to show how two hydrogen atoms can form a H2 molecule.

2. Use Lewis structures to show how two chlorine atoms can form a Cl2 molecule.

3. Draw hydrogen bromide

6. Draw a CHCl3 molecule

7. Draw an O2 molecule

8. Draw a N2 molecule

4. Draw a H2O molecule

9. Of all of these molecules, which has the strongest bond?

5. Draw a CH4 molecule

10. Draw sulfur dioxide NaC2H3O2

11.

Name the following molecules AlCl3

As2O3

PCl5

B

26


Name ___________________________ Period ___________

ws 7.8

Bonding Review Worksheet 1. Draw the Lewis dot structure for Bromine and indicate what type of ion it is likely to form.

2. Why do atoms form chemical bonds?

3. What is an ionic bond?

4. What is a covalent bond?

5. What is a metallic bond? 6. Draw the bond formula for sodium chloride, including the sodium to chlorine bond, and any lone pairs of electrons present:

7. What is the formula for calcium chloride?

8. Which ionic compound has the highest mass: MgCl2, MgBr2, or Mg I2?

9. What is the formula for iron (III) oxide?

10. What is the formula for chromium (VI) cyanide?

11. What is the formula of aluminum oxide?

12. Name me: Cu(NO3)2

13. Name me: ZrCl3 27


14. What are some differences between naming ionic compounds and covalent molecules?

15. A hydride anion has the formula H-. Write the formula for calcium hydride.

16. Fix me: Ammonium carbonate has a formula ofNH4(CO3)3

17. Fix me: Na2OH

18. Fix me: CH5

19. Fix the formula of ammonium hydroxide: NH3OH

20. What are the oxidation states of each atom in NaCl?

21. What are the oxidation states of each atom for CH4?

22. What are the oxidation states of each atom for the carbonate dianion?

23. Give the oxidation state of each atom of titanium (IV) chloride.

24. What are the differences in physical properties of metals and ionic compounds?

25. Draw the structure of carbon dioxide, including lone pairs.

26. Draw the structure of ammonia: NH3, including lone pairs.

27. Draw the structure of phosgene, COCl2, including lone pairs.

28


28. Draw the structure of sand: SiO2, including lone pairs.

29. Show the charges on each atom and the overall charge of the ozone (O3) molecule shown below:

30. L1 only: Draw the resonance structure indicated by the arrows:

O O

+

O

-

31. L1 only: Give the shape and bond angle of methane (CH4)

32. L1 only: Give the shape and bond angles of water: (H2O)

33. L1 only: Which molecule contains the strongest bond: Cl2, N2, or SiCl4?

34. Characterize each bond as ionic, nonpolar covalent or polar covalent: Cl2 (Cl-Cl bond) OF2 (O-F bond) NaOH (Na-O bond) SiF4 (Si-F bond)

29


7. How to Ace the Bonding Test

HTAIBondingUnit

In this our 7th unit we investigated bonding. We began by considering the basic idea of an ionic, covalent, or metallic bond. We then focused on ionic bonding. We considered the ions that elements in groups 1, 2, 3, 5, 6, and 7 would form, and how they could combine to form ionic compounds. We learned to write formulas and names for these compounds, and we took a look at their properties based on the nature of the ionic bond and the elements involved. This included both monatomic and polyatomic ions. We finished by mixing together lots of different ionic compounds, and predicted what products would form. For some classes this included memorizing all of the mono- and polyatomic ions, and balancing the chemical reactions of ionic compounds. We then briefly looked at metallic bonds, which are characterized by a sea of electrons, which helps explains the malleability and electrical conductivity of these materials. Finally, we investigated covalent bonding. Consisting of the bonds formed by sharing electrons between nonmetals, these are often organic (carbon-based) substance with a huge variety of chemical structures and properties. We spent much of our time assembling these molecules with models using bond and shorthand notation. We observed numerous examples of isomers, and learned how to name these types of molecules. We also took a look at several Connecticut biotechnology companies, focusing on what they do, and whether they may represent a good investment. In our next unit we will look at the reactions that these chemical substances undergo.

1. What is a chemical bond?

To ace this exam ask yourself: 2. What is an ionic bond?

3. What is a covalent bond?

4. What is a metallic bond?

5. What ions are formed from groups 1, 2, 3, 5, 6, and 7?. 7. Give an example of a polyatomic ion

6. Give an example of a monatomic ion:

9. Know how to write an ionic formula given a ionic compound name. Ex.: What is the formula for aluminum oxide?

10. Predicting the products of mixing ionic compounds. Ex. What two products form after mixing sodium iodide and potassium permanganate?

11. L1: Balancing reactions: Write a balanced equation based on mixing ammonium oxide and aluminum chloride.

12. How to write an ionic compound name given a formula. Ex.: Name Fe(CN)3.

13. What does oxidation number mean? Ex.: What is the oxidation number for silver in AgClO4?

14. Structures of ionic compounds. Draw the 3D lattice formed by NaCl:

8. Know the names and charges of all ions. For example, write the carbonate anion and the ammonium cation:

30


15. What are the typical properties of ionic compounds?

16. Why are ionic compounds not malleable, but metals are?

17. What are the typical properties of metals?

18. What is an alloy?

19. How does the electron sea model show the malleability of metals? Draw a cartoon.

20. Pick a Connecticut biotechnology company and describe what they do.

21. How do you calculate the value of a stock. Ex. You buy 1000 dollars of stock valued at 5 dollars per shareâ&#x20AC;Śit is now worth 4 dollars per share. How much money did you lose?

22. What is a covalent bond?

23. Which elements combine to form covalent bonds?

24. Use electron dot formulas to draw a chlorinechlorine bond, including lone pairs of electrons.

25. Know how to draw and interpret electron dot structures. Ex.: Draw the electron dot structure of oxygen. How many bonds would it form? How many lone pairs of electrons does it have?

26.

27. Be able to Interconvert molecular models, molecular formulas, bond formulas, and shorthand formulas. Ex.: Draw the bond formula and shorthand formula of any isomer of C3H6O.

28. Isomers. How many isomers are there with the formula C2H7N?

29. L1 only: Give the relative bond strenths, and the bond angle of carbon-carbon single, double, and triple bonds.

30. How to name covalent molecules. Name CO2, CF4.

31. L1 only: Draw two resonance structures using arrows for formaldehyde, CH2O.

32. Charged covalent molecules: Draw the electron dot structure for the oxygen anion.

33. Charged covalent molecules: Draw two resonance structures for the carbonate dianion.

34. Charged covalent molecules: Draw a bond formula for carbon monoxide. 31


35. Shapes of covalent molecules. Describe these molecules as linear, bent, or tetrahedral, and give the C-C-C bond angle: propene (C3H6), Propyne (C3H4), and propane (C3H8).

36.

37. Draw a diagram to relate the main topics of this unit:

38. How do atoms bond together? Be prepared to write a one page answer.

Bonding Ionic bonding Metallic bonding Covalent bonding Monatomic ions Polyatomic ions Monovalent ions Polyvalent ions HONC Lone pairs Diatomic molecules Electron dot formulas Bond notation Shorthand bond notation polarity

32


Name_________________________________ Period____

Name your molecule Each of you have received a molecular model. Please provide the common name, molecular formula, and scientific name for your molecule. Black: Carbon (C)

Yellow: sulfur (S)

White: hydrogen H)

Silver: sodium (Na)

Red: oxygen (O)

Purple: iron (Fe)

Blue: nitrogen (N)

Common name; uses Water For drinking Hydrazine For rocket fuel Ammonia For washing windows Carbon dioxide For soda Hydrogen peroxide Methane For the Bunsen burners Carbon tetrachloride For dry cleaning Carbon disulfide For smelling bad Table salt For your French fries Rust For getting rusty Phosgene For killing the Lye Sodium oxide ozone Chloroform

Formula

Scientific name

N2H4 NH3

COCl2 NaOH

33


Chemical Reactions

Unit 8 Ah, chemical reactions: the really fun part of chemistry. Mixing things together and standing back to watch what happens. After all, we now know plenty about chemical bonds (our previous unit)…it’s time to break some. We’ll be doing lots of that in this unit. We have three labs with plenty of opportunity to mix stuff, and identify strange substances. Our goals are to: 1. Figure out if a chemical reaction is occurring 2. Determine what type of reaction is occurring 3. Find out exactly what is going on by writing a balanced chemical equation 4. Become skilled at performing reactions by using appropriate solvents 5. Apply our knowledge to working with some acids and bases 6. Use all of this knowledge to identify mysterious unknown substances 7. Think about how we can perform chemical reactions using exactly the right amounts of reactantsthis will be the subject of our next unit: Stoichiometry. Tentative Schedule

Day 1 Lab: lab8.1: Evidence for a chemical change Lesson: Chemical change; writing chemical reactions Homework: ws8.1: Physical and chemical change ws8.2: Balancing chemical reactions Day 2: Lesson: 5 types of chemical reactions Lab: lab8.2: 5 types of chemical reactions Homework: ws8.3: predicting reaction products ws8.4: signs of a reaction/5types/balancing reactions Day 3 Lesson: Solvents; introduction to acids and bases Lab: complete previous labs Homework: Ws8.5 5 types of reactions Day 4 Lab: lab8.3: Identification of unknown chemicals Lesson: Review- how to ace this unit Homework: Review for unit test Day 5 Test: Chemical Reactions

1


Name:__________________________________

Period:______

lab 8.1

Evidence for a Chemical Change (10 Points) Purpose: To observe a sequence of changes that occur when a solution of copper (II) nitrate is treated with a series of different reactants. All the reactions occur in the same test tube. At each step you will look for evidence that a new substance is formed. Safety: Wear gloves, goggles and aprons. Materials: - 1 Test Tube - Aluminum Foil - Ruler - Evaporating Dish - 1.5 M HCl

- Bunsen Burner - 100 mL Beaker - Glass Stirring Rod - Cooper (II) Nitrate

- Ring Stand - Crucible Tongs - Wire Gauze - Sodium Hydroxide

Procedure: Four reactions will take place in one test tube. 1. Perform the first reaction by adding CuNO3 and NaOH to a test tube. What signs were there of a chemical reaction?

2. Keep this first product from this reaction and heat the test tube in hot water to produce a second product. What signs were there of a chemical reaction?

3. Keep the second product and add HCl to form a third product. What signs were there of a chemical reaction?

4. Keep the third product and add a rolled strip of Aluminum Foil to form the final product. What signs were there of a chemical reaction?

Please clean up and have your instructor sign off: Answer the questions on the other side of this paper at your desk.

2


1. The two new substances for the first reaction are in the tube are Copper (II) Hydroxide and Sodium Nitrate. Write a balanced chemical reaction down in the form A + B  C + D.

2. The products of the second reaction are Copper (II) Oxide and Water Write a balanced chemical reaction down in the form A + B  C + D.

3. The products of the third reaction are Copper (II) Chloride and Water. Write a balanced chemical reaction down in the form A + B  C + D.

4. There are two reactions occurring for the fourth reaction: Copper (II) Chloride + Aluminum  Copper + Aluminum Chloride Aluminum + Hydrochloric Acid  Hydrogen + Aluminum Chloride Write balanced chemical reactions down in the form A + B  C + D.

3


Name:___________________________________

Period:______

lab 8.2

Types of Chemical Reactions (10 Points) Purpose: To learn to differentiate among the five general types of Chemical Reactions. Safety: Wear gloves, goggles and aprons. Materials: - 5 Test Tubes Tongs - Iron Filings - 0.1 M KI Solution - 6M HCl

- Bunsen Burner - 0.1 M CuSO4 Solution - CuSO4 路 5 H2O - 3% H2O2

- Dropper Pipet

-

- 0.1 M Fe(NO3)3 Solution - Mg Ribbon

Procedure: Part 1: Iron Metal and Copper (II) Sulfate Solution: 1. 2. 3. 4. 5.

Fill a test tube 录 full of Copper (II) Sulfate Solution. Add approximately 2 g of Iron Filings to the Solution. Observe the Reaction for 5 minutes. Discard the Contents and clean the test tube. The two new substances are Iron (II) Sulfate and Copper.

What did you observe? ____________________________________________________ ___________________________________________________________________ How do you know a chemical change occurred? _________________________________ Write a balanced chemical equation for the reaction you performed: ___________________________________________________________________ What type of reaction was this? ______________________________________________ Part 2: Iron (III) Nitrate and Potassium Iodide Solution 1. 2. 3. 4. 5.

Put 2 mL of Iron (III) nitrate solution in a test tube. Add 5-10 drops of Potassium Iodide solution. Observe the Reaction that has occurred. Discard the contents and clean the test tube. The two new substances are Iron (III) Iodide and Potassium Nitrate.

4


What did you observe? ____________________________________________________ ___________________________________________________________________ How do you know a chemical change occurred? _________________________________ Write a balanced chemical equation for the reaction you performed: ___________________________________________________________________ What type of reaction was this? ______________________________________________ Part III. Procedure for heating Copper (II) Sulfate Crystals 1. Put a few pea size crystals of Copper (II) Sulfate Pentahydrate into a test tube. 2. Fasten a utility clamp to the upper end of the test tube. 3. Hold the tube by the clamp so that it is almost parallel to the surface of the lab bench.

Warning: Do not point the open end of the test tube at anyone. 4. Observe the material as you gently heat the tube in a Bunsen burner blame for 30 seconds. 5. Discard the contents and clean the test tube. 6. The new substances are Copper (II) Sulfate and Water.

What did you observe? ____________________________________________________ ___________________________________________________________________ How do you know a chemical change occurred? _________________________________ Write a balanced chemical equation for the reaction you performed: ___________________________________________________________________ What type of reaction was this? ______________________________________________ Part IV. Procedure for Magnesium Metal and Hydrochloric Acid 1. Fill one test tube ½ full of Hydrochloric Acid. 2. Place the test tube in a rack. 3. Put a small piece of Magnesium metal into the test tube. (1-2 cm in length) 4. If you observe a gas forming, test its identity by holding a burning wooden splint at the mouth of the test tube.

Warning: Do not put the splint into the solution.

5. Discard the contents and clean the test tube. 6. The two new substances in the tube are Hydrogen Gas and Magnesium Chloride.

What did you observe? ____________________________________________________

5


___________________________________________________________________ How do you know a chemical change occurred? _________________________________ Write a balanced chemical equation for the reaction you performed: __________________________________________________________________ What type of reaction was this? ______________________________________________ Part V: Procedure for Heating Hydrogen Peroxide 1. Add 2 mL of 3% Hydrogen Peroxide Solution to a test tube. 2. Use a utility clamp to secure the tube to the ring stand.

Warning: Do not point the open end of the test tube at anyone. 3. Observe the material as you very gently heat the tube.

4. If you observe a gas forming, test for its identity by carefully holding a lit match above the solution Warning: Do not put the match into the solution. 5. Discard the contents and clean the test tube. 6. The two new substances in the tube are Oxygen gas and Water. What did you observe? ____________________________________________________ ___________________________________________________________________ How do you know a chemical change occurred? _________________________________ Write a balanced chemical equation for the reaction you performed: ___________________________________________________________________ What type of reaction was this? ______________________________________________

6


Name_______________________ Period______ Date

lab8.3

Identification of Unknown Chemicals Experiment There are five flasks containing solutions that are unlabeled. They are: 1. Hydrochloric Acid in water: HCl (aq.) 2. Salt water: NaCl (aq.) 3. Sugar water: C6H12O6 (aq.) 4. Baking soda in water: NaHCO3 (aq.) 5. Pure Water: H2O (l). Your job is to figure out the identity of each unknown. As always, NEVER TASTE anything in the lab. Some of these chemicals, especially hydrochloric acid, are highly toxic. Solid and aqueous samples of each are available. Suggestions: Think about the reactivity of each substance. Is there something it will react with that will reveal itâ&#x20AC;&#x2122;s identity? -You may want to mix different combinations of 2 unknowns. Only mix a few drops of each: 1 mL of each unknown is all you get. -You may want to test the pH your unknowns and compare them to authentic samples.

On the following page, indicate the identity of each unknown, and your data that supports that conclusion.

7


1. Identity of unknown #1: Explanation:

2. Identity of unknown #2: Explanation:

3. Identity of unknown #3: Explanation:

4. Identity of unknown #4: Explanation:

5. Identity of unknown #5: Explanation:

8


9


10


11


12


13


Name________________________________Period_______________WS8.1 Physical and Chemical Change Worksheet Imagine a new spring day. The snow is melting, birds are singing. You’re inside by a warm fire, drinking hot cocoa. Consider all these changes that are going on from a chemists perspective. What is happening? Are all of these observations examples of chemical reactions? Or are they physical processes? In a physical change the identity of the substance is retained. For example, when water boils, it is converted from liquid water to steam- but it is still water. In a chemical change, the identity of the substance changes. For example, baking soda mixed with vinegar forms several new substances, including carbon dioxide gas. We can summarize four of the common signs of a chemical reaction by using the acronym COOL:

Color Odor Outgassing Lower or Higher Temperature Note that they are only signs- you may observe all of them and others as well, and it is still only a physical change. The only way to know for sure is to chemically analyze what happened. ___________________________________________________________________ 1. Ice melts. What are the COOL signs of a chemical reaction you observe? Is it a chemical reaction? 2. Wood burns. What are the COOL signs of a chemical reaction you observe? Is it a chemical reaction? 3. Iron rusts. What are the COOL signs of a chemical reaction Is it a chemical reaction? 4. Give an example of a physical change: 5. Give an example of a chemical change: 6. Describe three chemical reactions going on in your body right now: 1. 2. 3. 7. Describe a physical change and a chemical change while making s’mores (ask a friend if you don’t know what they are)

14


Check whether the process is physical or chemical observation

physical

chemical

You cut your hair Mixing sugar and water Making a peanut, pretzel and cereal mixture Baking soda reacts with vinegar and forms a gas A piece of metal is bent in half Methanol is burned and leaves a residue An aspirin is crushed into fine powder Copper turns green when exposed to the environment Two clear liquids are mixed and a yellow color forms Baking cookies Diamonds are used to scratch glass A tree burns to form ashes A piece of paper is crumpled up Water freezes to form ice

15


Name___________________________ Period____________________

ws8.2

Balancing Chemical Equations It was discovered in 1909 that if you mix nitrogen and hydrogen under the right conditions it will form ammonia (NH3), which is useful for cleaning windows, fertilizer, and munitions. It is now known as the Haber Process. But how much of each should you use? We can find out by writing a balanced chemical equation. We start by writing a chemical equation, and place lines in front of each reactant ____ N2 + ____ H2  ____ NH3 Substances often don’t react in a 1:1 ratio. To find out the ratios, we modify the number of molecules on each side until it is balanced. Look at the reaction above. There are two nitrogen atoms as reactants, but only one for product. We fix this by placing a 2 in front of the ammonia product. But now we have only two hydrogen atoms reacting, but they are forming 6 hydrogen atoms. We solve this by placing a 3 in front of hydrogen, and it is now balanced: 1 N2 + 3 H2  2 NH3 This tells us we need a lot of hydrogen for this reaction- three molecules of hydrogen for each molecule of nitrogen. ____________________________________________________________________________

Balance the equations below: 1)

____ KClO3  ____ KCl + ____ O2

2)

____ NaCl + ____ F2  ____ NaF + ____ Cl2

3)

____ H2 + ____ O2  ____ H2O

4)

____ CH4 + ____ O2  ____ CO2 + ____ H2O

5)

____ P + ____O2  ____P2O5

6)

____ Na + ____ H2O  ____ NaOH + ____H2

7)

____ Ag2O  ____ Ag + ____O2

8)

____ S8 + ____O2  ____ SO3

9)

____ K + ____ MgBr  ____ KBr + ____ Mg

10)

____ HCl + ____ CaCO3  ____ CaCl2 + ____H2O + ____ CO2

11)

____ HNO3 + ____ NaHCO3  ____ NaNO3 + ____ H2O + ____ CO2

12)

____ H2O + ____ O2  ____ H2O2

13)

____ NaBr + ____ CaF2  ____ NaF + ____ CaBr2

16


Balance the equations below:

Balancing Chemical Equations – Answer Key

1)

2 KClO3  2 KCl + 3 O2

2)

2 NaCl + 1 F2  2 NaF + 1 Cl2

3)

2 H2 + 1 O2  2 H2O

4)

1 CH4 + 2 O2  1 CO2 + 2 H2O

5)

4 P + 5 O2  2 P2O5

6)

2 Na + 2 H2O  2 NaOH + 1 H2

7)

2 Ag2O  4 Ag + 1 O2

8)

1 S8 + 12 O2  8 SO3

9)

1 K + 1 MgBr  1 KBr + 1 Mg

10)

2 HCl + 1 CaCO3  1 CaCl2 + 1 H2O + 1 CO2

11)

1 HNO3 + 1 NaHCO3  1 NaNO3 + 1 H2O + 1 CO2

12)

2 H2O + 1 O2  2 H2O2

13)

2 NaBr + 1 CaF2  2 NaF + 1 CaBr2

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Name: ____________________________________ Period: _____

ws8.3

Predicting Reaction Products Directions: Balance the equations and predict the products for the following reactions: Hint: Ionic compounds tend to undergo replacement. Combustion reactions have O2 as a reactant. They usually produce CO2 and water Lone reactants must decompose Pure metals can combine with halogens in a synthesis reaction.

Example:

_ Na + _ FeBr3 

Answer: 3 Na + 1 FeBr3  3 NaBr + Fe 1)____ NaOH + ____ HCl  2)

____ C2H4O2 + ____ O2 

3)

____ Mg + _____Cl2 

4)

____ PbSO4 + ____ AgNO3 

5)

____ PBr3 

6)

____ HBr + ____ Fe 

7)

____ KMnO4 + ____ ZnCl2 

8)

____Ag + ____ Sn(OH)4 

9)

____ O2 + ____ C5H12O2 

10)

____ H2O2 

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Predicting Reaction Products - Solutions

Balance the equations and predict the products for the following reactions: 1)

2 NaOH + 1 H2SO4  1 Na2SO4 + 2 H2O

2)

1 C2H4O2 + 2 O2  2 CO2 + 2 H2O

3)

1 Mg + 1 Cl2  1 MgCl2

4)

1 PbSO4 + 2 AgNO3  1 Ag2SO4 + 1 Pb(NO3)2

5)

4 PBr3  1 P4 + 6 Br2

6)

2 HBr + 1 Fe  1 H2 + 1 FeBr2

7)

2 KMnO4 + 1 ZnCl2  2 KCl + 1 Zn(MnO4)2

8)

4 Ag + 1 Sn(OH)4  1 Sn + 4 AgOH

9)

7 O2 + 1 C5H12O2  5 CO2 + 6 H2O

10)

1 H2O2  1 H2 + 1 O2

OR

OR

6 HBr + 2 Fe  3 H2 + 2 FeBr3

2 H2O2  2 H2O + 1 O2

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Name________________________Period___________

ws8.4

/ / 1. When someone smokes a cigarette, what are the signs of a chemical reaction? Is it a chemical reaction? What type of chemical reaction is it, if any? 2. When water boils, what are the signs of a chemical reaction? Is it a chemical reaction? What type of chemical reaction is it, if any? 3. Balance the following chemical reactions: a)

____ Ag2O  ____ Ag + ____O2

b)

____ S8 + ____O2  ____ SO3

c)

____ K + ____ MgBr  ____ KBr + ____ Mg

d)

____ H2O + ____ O2  ____ H2O2

e)

____ NaBr + ____ CaF2  ____ NaF + ____ CaBr2

4. For each reaction a- e, classify it according to which type it is: synthesis, combustion, decomposition, single replacement, or double replacement. a. b. c. d. e.

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Name________________________ Period____________ws 8.5 Types of Reactions Worksheet

Balance the following equations and indicate the type of reaction taking place: 1)

____ NaBr + ____ H3PO4  ____ Na3PO4 + ____ HBr

Answer: 3 NaBr + 1 H3PO4  1 Na3PO4 + 3 HBr

Type of reaction: ____________________

Type of reaction: double displacement 2)

____ Ca(OH)2 + ____ Al2(SO4)3  ____ CaSO4 + ____ Al(OH)3 Type of reaction: ____________________

3)

____ Mg + ____ Fe2O3  ____ Fe + ____ MgO Type of reaction: ____________________

4)

____ C2H4 + ____ O2  ____ CO2 + ____ H2O Type of reaction: ____________________

5)

____ PbSO4  ____ PbSO3 + ____ O2 Type of reaction: ____________________

6)

____ NH3 + ____ I2  ____ N2I6 + ____ H2 Type of reaction: ____________________

7)

____ H2O + ____ SO3  ____ H2SO4 Type of reaction: ____________________

8)

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____ H2SO4 + ____ NH4OH  ____ H2O + ____ (NH4)2SO4 Type of reaction: ____________________


Types of Reactions Worksheet – Solutions

Balance the following equations and indicate the type of reaction taking place: 1)

3 NaBr + 1 H3PO4  1 Na3PO4 + 3 HBr Type of reaction: double displacement

2)

3 Ca(OH)2 + 1 Al2(SO4)3  3 CaSO4 + 2 Al(OH)3 Type of reaction: double displacement

3)

3 Mg + 1 Fe2O3  2 Fe + 3 MgO Type of reaction: single displacement

4)

1 C2H4 + 3 O2  2 CO2 + 2 H2O Type of reaction: combustion

5)

2 PbSO4  2 PbSO3 + 1 O2 Type of reaction: decomposition

6)

2 NH3 + 3 I2  1 N2I6 + 3 H2 Type of reaction: double displacement

7)

1 H2O + 1 SO3  1 H2SO4 Type of reaction: decomposition

8)

1 H2SO4 + 2 NH4OH  2 H2O + 1 (NH4)2SO4 Type of reaction: acid-base

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Name________________________________ Period_________

howtoaceit8.1

How to Ace the Reactions Exam

In this our eighth unit we explored the world of chemical reactions. This is the fundamental chemistry process: mixing things together and seeing what happens. We began by looking for the 4 COOL signs of a chemical reaction. We then focused on writing balanced chemical reactions- this is probably the toughest part of the unit. Be sure to know how to write ionic compounds correctly- we can’t balance a reaction unless it is written accurately. We then performed each of the 5 types of reactions, to get a feel for each one. In many cases we are now able to predict the products of a reaction. Ionic compounds tend to undergo replacement, combustion reactions often give the same products, and decomposition reactions often form stable common substances. To wrap up this unit we looked at the advantages of using solvents for chemical reactions. We took a sneak peek at acids and bases, which are really a subset of ionic compound s. We completed the unit by looking at reactions from the point of view of what really strikes your eye: precipitates. Performing and balancing reactions shows us the ratio that substances react in, but it still doesn’t tell us how much to mass out to do these reactions properly. This is the topic of the next unit: Stoichiometry and the Mole. To ace this unit review your notes, labs, worksheets, and this how to ace it guide. 1. What are the 4 signs of a chemical Reaction?

Suggest two other possible signs of a chemical reaction. Give examples of signs of a chemical reaction that are false positives.

2. Balancing Chemical Equations -given formulas: ___H2 + ___O2  ____H2O -given word equations: mixing hydrogen and oxygen can create water. -given starting materials only, predict the product: Write a balanced chemical equation describing the reaction of sodium chloride and Magnesium fluoride. -combustion. Write a balanced chemical equation for burning hexane (C6H14).

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-practice writing ionic formulas: calcium hydroxide; iron (II) sulfate, etc. Ion charts will be available, as will the periodic table with the names of each elements. You will save a great deal of time by memorizing the common ions and elements.

3. The 5 types of reactions: 4. Precipitates- what is a precipitate?

5. Why solvents are your friends:

6. Solute and solvent:

7. Acids and bases: what they are; how they react.

8. The difference between salt water and sugar water: 9. Consider the chemical reactions you experience each day. You get up. You are breathing…that’s good. Now a biochemist could spend hours explaining it, but to us chemists you are taking in oxygen, it combines with carbon, and you exhale carbon dioxide. You’re doing it right now. We can write this as a balanced chemical reaction indicating the physical states (s, l, g, or aq) of the reactants and products as: ________( ) + _______ ( )  ________ ( ). OK, next you make a cup of tea. You put the kettle on, and your gas stove lights up. Yes, you have a gas stove, which uses a big propane tank next to your house. This is the combustion of propane (C3H8), which we can write as a balanced chemical reaction: ________( ) + _______ ( )  ________ ( ) + ________( ). You drink the tea, and eat something. Your body converts this food to energy using enzymes to catalyze the reactions, and the process is complex. Time for school. You hop in the car and fire it up, and the combustion of the hexane (C6H14) takes place in your engine: ________( ) + _______ ( )  ________ ( ) + ________( ). At school everything is going fine, but then you start to feel sick, and you go see the nurse. You are diagnosed with a sour stomach, and the nurse suggests you add some milk to your tea next time. She gives you some antacid tablets (Na2CO3) which react with the excess hydrochloric acid in your stomach: ________( ) + _______ ( )  ________ ( ) + ________( ). And you feel much better. The rest of the day is yet another wonderful day of learning at Guilford High School. You confidently ace your chemical reactions test

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The Mole

How heavy are molecules? Unit 9 In our last unit we learned how to mix chemicals and predict the products of the chemical reaction. What we didn’t learn is the amounts that are involved. That’s what this unit is all about. To do this will explore the mole, which is a unit of measure that enables us to find out exactly the amounts and the masses involved in any chemical reaction. Tentative Schedule Day 1: What is the mole and why is it important? Lab: Introduction to the mole Lesson: The Mole (slides 1-4) Homework: I’d like a mole worksheet 9.1 (in class) Reactions using the mole worksheet 9.2 Day 2: Using the mole Lab: Neutralization lab (slides 5-6) Lesson: Stoichiometry and the space shuttle (slides 7-8) Homework: Grams and moles worksheet 9.3 How to solve basic stoichiometry questions workseet 9.4 Day 3: Solving Stoichiometry Problems Lesson: Three types of stoichiometry problems (slides 9-14) Homework: Stoichiometry mixed problems worksheet 9.5 Day 4: Mixed Stoichiometry Problems Lesson: In class problem solving: More mixed stoichiometry problems worksheet 9.6 Tougher stoichiometry problems worksheet 9.7 Homework: How to solve limiting/excess reactant problems worksheet 9.8 Day 5: Yield and Percent Composition; Limiting Reactant Lesson: Yield and % Composition; Limiting Reactant (slides 15-19) Homework: Limiting reactant worksheet 9.9 Percent Composition worksheet 9.10 Day 6: Molar Volume and Review Lab: Molar Volume of Hydrogen Lesson: Review How to Ace it guides Homework: Review for mole and stoichiometry test Day 7: Test on the mole and stoichiometry

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2


Name:_______________________________________

Period:______

Lab 9.1

Introduction to the mole lab. (10 Points) Goal: To learn the practical utility of the mole. Introduction: It would be very easy to mix chemicals together if all atoms had the same mass. For example if we needed to make some magnesium sulfide, where Mg + S  MgS

Mg

+

S

Mg

S

We could simply mass out 10 grams of magnesium and 10 grams of sulfur, cook them up, and we would have 20 grams of magnesium sulfide. However, in reality each atom of sulfur weighs about 25% more than each magnesium atom:

Mg

+

S

Mg

S

Our ten-grams-of-each recipe would have too many _______ atoms and not enough _________ atoms. The perfect ratio is 24.3 grams of magnesium for every 32.1 grams of sulfur. This mixture allows for every magnesium atom to react with the same number of sulfur atoms- none are wasted. We call this a stoichiometric ratio. It is simply based on the fact that some elements are heavier than others. 24.3 grams of magnesium is a mole of magnesium. 32.1 grams of sulfur is a mole of sulfur. These are handy numbers. Find them on the periodic table. They are simply the atomic masses of each atom expressed in grams, readily found on any periodic table. They each contain the same number of atoms: 6.02 x 1023 atoms. This is known as Avogadro’s Number. As you can see, the mole is a convenient way to count out huge numbers of molecules by weighing them on a balance. The same kind of relative mass problems occasionally happen in the real world- we need to combine tiny things – too small to count - in the right ratio by weighing them. Putting molecules together is in some ways like attaching a nut to a bolt. The parts have a structure that allows them to combine, and they do not have the same mass. This lab will show you these kinds of combinations can be performed on any scale.

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Situation number one: Nuts and Bolts Puzzle Each of you will be given one nut and one bolt. You need to buy a lot of these: 10,000 nuts and 10,000 bolts. They combine in a 1:1 ratio: 1 nut + 1 bolt ď&#x192;  1 widget (ok, I made up the name) Think of a way to obtain 1000 nuts and 1000 bolts, not by counting them, but by weighing them. 1. Our plan (1 point): To create a pile of 10,000 nuts and 10,000 bolts without counting them, we will_______________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ ________________________________________________________________________ 2. Our data (1 point): This should include the mass of one nut and one bolt.

3. Our calculations (1 point). Be sure a stranger could follow your logic.

4. Conclusion (1 point): Based on our data, to get 10,000 nuts and bolts we need to mass out ________ grams of nuts and _________ grams of bolts. Extrapolating 5 (1 point). If our boss needed 5 million nuts and 5 million bolts, no problem. We would simply mass out ______ grams of nuts and _______ grams of bolts. Situation number two: Paper clip puzzle. Large paper clips = oxygen Medium paper clips = carbon Small paper clips = hydrogen Assemble a molecule of ethanol, C2H6O (see drawing below) Assemble a molecule of acetic acid, C2H4O2 (See drawing below) Mass them. Mass ethanol:_______g Mass acetic acid__________g

These two molecules combine to form ethyl acetate: H H H C C O H

H O

H O

+

H C C

O H

H H

H

ethanol

acetic acid

H C C H

O

H

H

C

C

H

H

ethyl acetate

H

+

H O H

water

4


Note the stoichiometric ratio: 1 molecule of ethanol combines with 1 molecule of ethyl acetate to form 1 molecule of ethyl acetate and 1 molecule of water. Using this data, we can combine any number of our paper clip molecules using mass: 6. (1 point). To make 10 molecules of ethyl acetate, combine _____ grams of ethanol with ______ grams of acetic acid 7. (2 points) Assemble the two products and show the masses of all four products below: H H H C C O H

H O

H O

+

H C C

O H

H H

H

ethanol

acetic acid

_____ g

_____ g

H C C

O

H

H

H

C

C

H

H

ethyl acetate _____ g

H

+

H O H

water _____ g

8. (1 points) Is the law of mass balance conserved? Please explain.

9. Please disassemble your molecules and return them to their cups, and have your lab stamped by your instructor. (1 point).

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6


Lab9.2 Name__________________________Date_________________Period______________ Using the Mole: Neutralization Lab 5 Points Common acids and bases react to form a salt, and water. For example: HCl (aq) + NaOH (aq) ď&#x192;  NaCl + H2O When equivalent amounts of acid and base react, the solution becomes neutral. This can easily be confirmed using pH paper. If we use too much acid or base the excess remains, and the solution is not neutralized. Again, we can find out with pH paper by checking the pH of the solution. We can use the mole to perform any reaction using exactly the right amounts. For example, in the above reaction, if we were given 36.5 grams of HCl (1 mole) we would need to use 40 grams (1 mole) of NaOH to neutralize it. Too much NaOH, and the solution is basic- it will turn pH paper blue. If we use too little, the solution remains acidic, and the pH paper will be red. In this experiment I will give each of you some acid (acetic acid), and you must use a base (baking soda) to neutralize it. Once you have done so, come up to me and I will test the pH of the solution. Your grade will be determined by the pH of your solution. Here is the chemical reaction:

H O

H O NaHCO3

+

H C C

O H

H baking soda _____ g _____ mol

acetic acid _____ g _____ mol

H C C

O

Na

+

H O H

H ethyl acetate

water

+

CO2 carbon dioxide

_____ g

_____ g

_____ g

_____ mol

_____ mol

_____ mol

If time permits, we can use different bases to neutralize the solution. Instructions: Work in groups of 2. 1. Put on safety gear- goggles, gloves, and aprons. 2. I will pass out random amounts of baking soda (NaHCO3) to each group. 4. Complete the table above, and use it to Neutralize the solution using the correct amount of acetic acid. 5. Come up to me when you are ready to have the pH checked. 6. Clean up when you are finished

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Name: ______________________________________

Date: ______

Period: _____

WS9.1

Iâ&#x20AC;&#x2122;d like a mole, please Chemists use the mole all the time to figure out how many atoms or molecules are in a substance. The mole is an amount (6.02 x 1023), also know as Avogadroâ&#x20AC;&#x2122;s number. More importantly, the average atomic mass in grams for each element has exactly one mole of atoms. For example, a mole of carbon has a mass of 12.01 g, and those 12.01 grams contain 6.02 x 1023 atoms of carbon. We can say that the molar mass of carbon is 12.011 grams per mole. If I needed half a mole of carbon I would mass out 6 grams of carbon, and that would contain 3.01 x 1023 atoms of C. Similarly, 24 g of C is 2 moles of carbon, and contains 1.2 x 1024 carbon atoms. Example: What is the molar mass of water, and how many water molecules would it contain? Solution: Water is H2O. We can find the molar mass by adding up the average atomic masses: 2(1.01) + 16.00 = 18.02 grams/mol. Since this is one mole of water, it will contain 6.02 x 1023 water molecules. ______________________________________________________________________________ Use these relationships to answer the questions below. 1. A mole of aluminum contains _____ g of aluminum, and also consists of ____________atoms of aluminum. If I needed 2 moles of aluminum, I would mass out ______ grams of aluminum, recognizing that it contains______________ aluminum atoms. 2. A mole of TNT (trinitrotoluene, C7H5N3O6) NO2 H

H O2N

NO2 H

H

has a mass of ________grams. If I had 0.1 moles of TNT it would have a mass of _________ grams, and would consist of _____________ molecules of TNT. H

3. The lightest element is ________;a molecule of this element has a molar mass of _________g/mol (remember, in this class, like in the real world, we will use the terms molar mass and mole interchangeably). 4. Determine the molar mass of each of the following molecules: A. Sugar (C6H12O6): B. The smell of fish: triethylamine:

N C. Carbon dioxide D. Water

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Name_________________________ Period______________

WS9.2

Reactions using the mole The mole can be used to find out the how much material is required for a reaction, and how much it produces. For example, lets make a mole of water from the elements: 2 H2 (g) + O2  2 H2O (l) This equation tells us that 2 moles of molecular hydrogen react with one mole of molecular oxygen to form 2 moles of liquid water. But if we were to really to make water this way, how much of each reactant should we mix? We can look up the average atomic masses (the “red numbers” on our periodic table) to see the relative amounts needed and produced: ____ grams of H2 react with ____ g of O2 to form ____ grams of water. Since this reaction makes two moles of water, we have performed this reaction on a 2 mole scale. _____________________________________________________________________________ Show the amounts involved when each of these reactions is performed on a one mole scale; the first is done for you. 1.

Mn + O2  MnO2 55 g 32 g 87g

2. Ba + F2  BaF2 ___ ___ ____ 3. Mg + Se  MgSe __ ___ ____ Here are some that don’t react in a 1:1 ratio: 4. 2 H2 + O2  2 H2O (done for you) 4g 32g 36g 5. 2 Li + Cl2  2 LiCl ____ ___ ____ 6. 2Al + 3 Cl2  2 AlCl3 ____ ____ ____ 7. If I burn a mole of methane, how much carbon dioxide will it produce? CH4 + 2O2  CO2 + 2H2O 16g ____ ____ ____ 8. We can make chalk by reacting lime (calcium chloride) with soda ash (sodium carbonate). Fill in the amounts necessary to make one mole of chalk.

CaCl2 + Na2CO3  2 NaCl + CaCO3 ____ _____ ____ _____ 9. Try one based only on words: How would you make one mole of methane from the elements?

10. A perfume chemist needs 102 grams (1 mole) of ethyl propionate, which has an odor similar to bananas. How much propionic acid , and how much ethanol should he mix? CH3CH2CO2H + CH3CH2OH  Propionic acid ethanol _____________ _________ CH3CH2CO2CH2CH3 + H2O Ethyl propionate water ____________ ____

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Name_________________________ Period_____________

How to Solve “Basic” Stoichiometry Questions

WS9.4

All of the following questions are based on lighting butane on fire, for which we can write the following balanced equation, :

2 C4H10 + 13 O2  8 CO2 + 10 H2O Note the molar ratio of 2:13:8:10. In the world of Stoichiometry we consider all of these to be “equivalent”: 2 moles C4H10 = 13 moles O2 = 8 moles CO2 = 10 moles H2O. Note how each example uses these conversion factors.

Type 1: Moles to Moles # of Steps: 1 1) Take your initial number of moles and use the balanced chemical equation to convert moles of the required chemical. Example : How many moles of O2 are required to produce 8 moles of H2O? (For all of these problems we will assume there is an excess of the other reactant that is needed, which in this case is H2) 8 moles H2O x 13 moles O2 = 10.4 moles O2 10 moles H2O

You try some: 1. How many moles of O2 are required to produce 240 moles of H2O?

2. How many moles of butane (C4H10) are needed to produce 25 moles of water?

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Type 2: Moles to Grams and Grams to Moles Problems # of Steps: 2 These are like mole to mole problems, with the added step of adding up the molar masses of the substance in question to determine the number of grams needed or created. Example: How many grams of O2 are required to produce 9 moles of CO2? 9 moles CO2 x 13 moles O2 x 32 grams O2 = 468 grams O2 8 moles CO2 1 mole O2 You try one: How many grams of CO2 will be produced from 17 moles of O2?

Here is a grams to moles problem. They are just like moles to grams problems, but in a different order. Example: How many moles of C4H10 are required to produce 54 grams of H2O? 54 grams H2O x 1 mole H2O 18 grams H2O

x

2 moles C4H10 10 moles H2O

= 0.6 moles C4H10

You try one: How many moles of C4H10 are required to produce 100 grams of CO2?

Type 4: Grams to Grams # of Steps: 3 These are three- step problems. We have to convert from the grams given to moles, then from the moles of that substance to the equivalent number of moles of the desired substance, and then finally we convert from the moles of that substance to the equivalent number of grams.

To put it another way, we go from grams to moles, then moles to moles, then moles to grams.

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Example: How many grams of H2O are produced from 40 grams of O2? 40 grams O2 x

1 mole O2 x 10 moles H2O x 18 grams H2O = 17.31 grams H2O 32 grams O2 13 moles O2 1 moles H2O

You try one: How many grams of butane (C4H10) are required to produce 25 grams of CO2? Type 5: Converting to molecules or atoms Since the mole is an amount,

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Name_________________________ Period_____________

WS9.5

Stoichiometry Mixed Problems Example: For the reaction 2 H2 + O2  2 H2O, if you burn 10 grams of hydrogen with excess oxygen, how many moles of water will you make? Solution: this is a grams to moles problem :

10 grams H 2 x

mole H 2 2 moles H 2 O x  5 moles H 2 O 2 grams H 2 2 moles H 2

1. The reaction of magnesium sulfate with table salt produces magnesium chloride and sodium sulfate. Balance the reaction below: _____MgSO4 + _____NaCl  ____MgCl2 + ____Na2SO4

Use the equation in question 1 to solve, questions 2 and 3. 2. How many moles of NaCl must be used in order to produce 42.1 moles of Na2SO4?

3. How many moles of MgSO4 must be used in order to produce 100 moles of MgCl2?

4. _____V + _____O2  _____V2O5

Use the equation in question 4 to solve, questions 5 and 6. 5. How many moles of Vanadium are required to produce 47 grams of V2O5? Period: _____

6. How many grams of Oxygen gas are required to produce 31.4 grams of V2O5?

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How to Solve Limiting/Excess Reactant Problems

WS9.8

In nature and in the lab, substance are being mixed together in all kinds of amounts. How much product will form? Here is a typical example. Example: If I mix together 10 grams of hydrogen with 10 grams of nitrogen, how many grams of ammonia (NH3) will I make? First we need to write a balanced chemical reaction: 3 H2 + N2  2 NH3 Next, we see how much product each reactant can make. The one that makes less is the limiting reactant. It’s like it sounds- it limits how much product can be made.

mole N2 2 mole NH3 17 g NH3 x x  12.1 g NH3 28 g N2 mole N2 mole NH3 mole H2 2 mole NH3 17 g NH3 10 g H2 x x x  56.7 g NH3 2 g H2 3 mole H2 mole NH3 10 g N2 x

This tells us that nitrogen is the limiting reactant. We can see how much H2 was wasted by seeing how much is needed:

10 g N2 x

2 g H2 mole N2 3 mole H2 x x  2.1 g H2 28 g N2 mole N2 mole H2

The rest of the hydrogen (7.9 g) is wasted. In summary, to perform limiting reactant problems 1. Write a balanced chemical reaction 2. Identify the limiting reactant by calculating how much product each reactant can make. The one that makes less is the limiting reactant. 3. To figure out how much excess reactant there is, see how much is needed and compare that to what you used. Use this example to guide you through these 2 problems. 1. Determine the mass of Tetraphosphorus Decoxide (P4O10) which is formed from 25.0 grams of Phosphorus (P4) and 50.0 grams of Oxygen gas (O2).

2. You start with 200.0 grams of Vanadium (V) and 100.0 grams of Oxygen Gas (O2) and the only product is Vanadium Oxide (V2O5). a) What is the limiting reactant? b) How many grams of Vanadium Oxide (V2O5) can form? c) How much excess reactant remains?

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Limiting Reagent Worksheet

WS9.9

All of the questions on this worksheet involve the following reaction: When copper (II) chloride reacts with sodium nitrate, copper (II) nitrate and sodium chloride are formed. 1)

Write the balanced equation for the reaction given above:

2)

If 15 grams of copper (II) chloride react with 20 grams of sodium nitrate, how much sodium chloride can be formed?

(13 g) 3)

What is the limiting reagent for the reaction in #2? __________________

4)

How much of the excess reagent is left over in this reaction?

5)

(0.88 g) If 11.3 grams of sodium chloride are formed in the reaction described in problem #2, what is the percent yield of this reaction? (87%)

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Name__________________________Period______________

WS9.10

Percent Composition Worksheet

1. What is the percent composition of table salt (NaCl)

2A. What is the percent composition of carbon dioxide?

2B.How many grams of oxygen are present in an 88.0 g sample of carbon dioxide (CO2)?

3. What is the percent composition of sucrose (C12H22O11)?

4. What is the percent composition of aluminum sulfate (Al2(SO4)3)?

5. Which of the following compounds contains the highest percentage of iron? (Hint: compare the percent compositions) FeS2 Fe2O3 FeCO3

6. Caffeine has a chemical formula of C8H10N4O2. a) What is the molar mass of caffeine?

b) What is the percent composition of caffeine?

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How to ace the mole test L1 Chemistry

In the previous unit (chemical reactions) we learned qualitatively how chemicals react. In this our 9th unit we took a quantitative look at chemical reactions by studying The Mole. We took a practical approach, emphasizing how the mole (usually referred to as molar mass) is used everyday to perform chemical reactions. The key idea is that each element has a unique characteristic mass- the average atomic mass. The mole is simply that mass in grams. Since that number is scaled to the mass of the substance, it means it will always equal the same number of particles. This number is Avogadro’s number: 6.02 x 1023. Practicing chemists very rarely use Avogadro’s number, and very often use molar mass. This unit emphasizes molar mass: the practical application of the mole. Still not clear? Well, the examples are easier to follow. 12.011 grams of pure carbon (for example a 12.011 gram diamond) is a mole of carbon and would contain 6.02 x 1023 atoms of carbon. 16 grams of methane (CH4) would be approximately one mole of methane (12 grams for carbon, and one gram for each hydrogen) and would contain 6.02 x 1023 molecules of methane. With the mole it is easy to create recipes that allow chemicals to react in exactly the right amounts, with nothing wasted. For example, reacting 12 grams of carbon (1 mole) with 32 grams of oxygen (that’s one mole of O2) will produce exactly one mole (44 g) of carbon dioxide. Using the mole we can perform any chemical reaction using just the right amount of reactants, so that nothing is wasted. We can also predict the exact amounts of each product formed. Using the mole we can also calculate the percent composition of any substance, a great tool for chemical identification. Water, for example, is always 89% oxygen, and 11% hydrogen. We know this because each mole of water must consist of one mole of oxygen atoms (16 g) and 2 moles of hydrogen (2 g)…so water is 16/18 oxygen, and 2/18 hydrogen by mass. **********************************************************************************************

To ace the mole test you should emphasize the following topics: 1. Know what the mole is- both in terms of how many particles, and in terms of mass.

Ex: a mole of carbon dioxide has a mass of ____ g and contains ______molecules.

2. Be able to measure out one mole of any substance, or any fraction thereof.

Ex: To give me a mole of water you would mass out ____ g.

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3. Be able to perform a chemical reaction on any scale using the mole. This is perhaps the most common use of this handy topic.

Ex. To make 2 moles of water from the elements, the balanced chemical equation is: _________ + __________ --> _______ so I should mix ___g of hydrogen and ___g of oxygen

4. For any chemical reaction, be able to determine the number of molecules that are involved.

Ex. The above reaction uses ____molecules of hydrogen and ____molecules of oxygen to make ____ molecules of water.

5. Be able to predict the percent composition of any substance.

Ex. Ammonia (NH3): ___%N, ___%H

6. We should be familiar with all types of mole conversions: mole-mole (1 step), mole-gram or gram-mole (2 steps), and mole-mole (3 steps).

Examples: The combustion of one mole of hydrogen with excess oxygen will produce ____ moles of water.

The combustion of 4 moles of hydrogen with excess oxygen will produce _____ grams of water.

The combustion of 4 grams of hydrogen with excess oxygen will produce ___ grams of water. 7. We should be familiar with the concept of a limiting reactant. This is indispensable whenever any amounts of reactants are combined. Unless the stoichiometric amounts are used, this will create a situation where one reactant is in excess, and the other is limiting. We used a non-intuitive but useful method for solving these problems: we find out how much product each reactant will produce, and the lower amount “wins” – it defines the limiting reactant and therefore indicates how much product will form.

For example, what will happen when one gram of hydrogen is combined with one gram of oxygen? 1 g H2 x ____________ x___________ x _________ = g H 2O 1 g O2 x ____________ x ___________ x ___________ = g H2O The limiting reactant is _____, and this reaction will produce ______ g H2O. We learned a quick method for determining how much excess reactant there is- the ratio for the grams of product formed shows how much reactant was consumed. For the reaction above, since oxygen is the limiting reactant, the amount of hydrogen left is:

1 g H2 – 1g H2 (__/___) = _____ g excess hydrogen.

8. Finally, we learned to calculate the yield of a reaction; this is the actual yield/the theoretical yield x 100.

For example, if this reaction above produced 0.1 grams of water, the yield would be ( ___g/____g) x 100 = ____% yield.

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Since this unit has a lot of mathematical conversions that follow the same series of steps, it is useful to drill them. There are also a couple of vocabulary problems. Practice them tonight. 1. What is stoichiometry? 2. Where does the word come from? 3. How to balance chemical reactions- try mixing barium chloride with sodium fluoride. Put your molar masses below to help answer all questions. Do this carefully- it will be used in several subsequent questions.

Molar masses:

__________ + ___________ --> ___________ + __________ Barium chloride sodium fluoride barium fluoride sodium chloride _____ g/mol ______ g/mol _____g/mol ________ g/mol

4. Coefficients (the numbers in front, like 2 H2O) vs. Subscripts (the little numbers, like 2 H2O)

Example: In the equation above put circles around each subscript, and squares around each coefficient.

5. Mole ratios : what are they for the above reaction?

___________ moles barium chloride = _______ moles sodium fluoride = _________ moles _____________ = _________ moles _______________

6. Mole-mole conversions

Example: 2.1 moles of barium chloride will make _____ moles of sodium chloride

7. Mole-mass conversions

Example: ten moles of barium chloride will make _____ grams of sodium chloride

8. Mass- mass conversions

Example: 100 grams of barium chloride will make ____ grams of sodium chloride.

9. Limiting reactants

Example: 100 grams of each reactant above will make _____ grams of sodium chloride. The limiting reactant is ____________.

10. Excess reactants.

In the example above, ________ is the excess reactant, and _____ grams of it remains in the pot after the reaction is complete.

11. Theoretical yield (this is 100% yield).

In the example above the theoretical yield of sodium chloride is ___ g.

12. Actual yield.

Example: If 50 grams of sodium chloride was obtained, that is a ____% yield.

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Gases Unit 10

How do gases behave? Gases are perhaps the most mysterious of all of the phases of matter. For the most part gases are invisible to us, and it was once believed that in the air there is no matter at all. Consider, however, how finely tuned our own bodies are to gases in general, and oxygen in particular. We would die in a few minutes if deprived of oxygen, and our respiration system is in constant motion to take advantage of this energy-providing gas. The goal of this unit is to discover how gases behave physically. Or to state it more specifically, how do gases behave as temperature, volume, or pressure change? The first lab is designed to give you enough equipment to discover these things on your own. We will then compare these observations to the known Gas Laws. Tentative Schedule: Day 1: Introduction to gases activity: Lab 10.1 Homework: Complete lab report. Day 2: Comparison of the Class Gas Laws to the known Gas Laws (Slides 1-8) Homework: Complete WS10.1 (Boyle’s Law), 10.2 (Charles Law), and 10.3 (Gay-Lussac’s Law). Day 3: Avogadro’s Principle; Ideal Gas Law (Slides 9-11) Homework: Complete WS10.4 (Avogadro’s Principle) and 10.5 (Ideal Gas Law). Day 4 Gases Review Homework: Complete “How to ace the Gases Unit” Day 5: Gases Test

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Name_______________________________ Date: ______ Period:_____

Lab10.1

Introduction to Gases Activity Introduction: The goal of this activity is to see how three physical properties of gases- volume, pressure, and temperature - relate to one another. These processes are interacting constantly, but you may have never looked at them very deeply. At each station, design your own experiment, and take whatever measurements you think will be helpful. Not all of the equipment at each station is necessary to perform the experiment. At each station you are asked to determine the relationship between two specific gas properties. For example, at the first station you will measure how gas pressure affects gas volume. At the last station you can create any safe experiment you choose to see how gases behave physically. As for all experiments, safety is critical. You must wear goggles at all times to perform these experiments. If there is any question in your mind as to the safety of your experiment, do not perform it. Note that there will be up to four people at each station. Work together and share ideas. This report must be filled out and submitted for each group of two. This report will be graded on the validity of your experiment and the interpretation of your results. Although each experiment is brief, remember to include a control whenever possible, and to only include one independent variable. The best experiments will give data that can be graphed using numbers- these are quantitative experiments.

Note: Pay particular attention to your graphs. Although time is limited, try to get enough data points to see if the relationship is linear, or if your lines are curved.

Station 1: Syringe. This station contains a syringe and some books. Your goal is to discover how gas pressure and volume are related. Describe briefly the experiment you performed. (Remember, the best experiments give quantitative results)

What did you discover about gas pressure and volume? Answer this question, and complete a brief graph, labeling both axes.

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Please restack your books and clean your station before you leave.

Station 2: Popcorn

You have available a popcorn popper and some popcorn kernels, and a thermometer. Your goal is to discover how gas pressure and temperature are related. Describe what you did, and what you observed:

What did you discover?

For your experiment, hypothesize as to what gas may be involved in your experiment:

Complete a brief graph that shows the relationship between temperature and pressure, labeling both axes:

Please throw out any popped popcorn and clean your station before you leave.

Station 3: Vacuum Pump. This station includes a mechanical vacuum pump, a balloon, a marshmallow, a glass of water, and a thermometer. Your goal is to discover how reduced pressure and volume are related. Safety warning: Use care when working with the large glass bell jar.

Describe what you did, and what you observed:

What did you discover? Consider the relationship between any pressure and reduced volume.

Complete a brief graph summarizing this relationship:

Please clean up this station and turn off the pump before you leave.

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Station 4: Balloon.

This station contains balloons, string, a thermometer, and a hair drier. Caution: The hair drier must be kept from moisture, and will get hot. Your goal is to determine the relationship between volume and temperature. For this experiment you should obtain quantitative, graphable results. Describe what you did, and what you observed. Include a brief graph using real data.

Describe what you observed:

What did you discover? Consider the relationship between gas temperature and volume.

Station 5: ( Varies)

This station contains various equipment. Use it to create your own experiment that investigates a P,V,T relationship.

Describe what you did, and what you observed:

What did you discover? Consider the relationship between any of the following: temperature, pressure, and volume.

Our Gas Laws Please be sure to complete this part: these are your own gas laws that you discovered :) 2. What did you learn about the interaction of pressure, temperature, and volume of gases? Summarize your results by using an up arrow ( ) for increasing, a down arrow ( ) for decreasing, and write constant if this property is unchanged. Support each case with examples. Temperature Volume Pressure Example

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Name: _____________________________________

Date: _____ Period: _____

WS10.1

Boyles’ Law Practice Problems When you press on a closed syringe with only air in it, the volume goes down, and the pressure goes up. This shows the fundamental relationship between the pressure and volume of a gas at constant temperature. Boyle wrote it mathematically: P1V1=P2V2 where P1 is the original pressure P2 is the final pressure V1 is the original volume V2 is the final volume For this formula any units can be used as long as they cancel. The preferred (SI) units are liters and atmospheres. Example: A 10 liter oxygen cylinder is under 800 atmospheres of pressure. When the oxygen is released to the air (1 atmosphere), what will the volume of the oxygen be? Solution:

P1V1  P2V2 ; (800 atm)(10 L)  (1 atm)(V2 ); V2

(800 atm)(10 L)  8000 L (1 atm)

1. A balloon filled with helium gas has a volume of 500 mL at a pressure of 1 atm. After the balloon in released, it reaches an altitude of 6.5 km, where the pressure is 0.5 atm. What volume does the gas occupy at this height?

2. A sample of oxygen occupies a volume of 5 L at a pressure of 200 mm Hg. After undergoing an increase of pressure, the new volume is 2.5 L. What must the new pressure be?

3. If the pressure exerted on a 240 mL sample of hydrogen gas is increased from 325 mm Hg to 550 mm Hg, what will the final volume of the sample be?

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Name: ______________________________ Date: ______

Period: _____

WS10.2

Charles’ Law Practice Problems A balloon will expand as it is heated: as the temperature of a gas increases (at constant pressure), volume increases. Charles wrote this mathematically:

T1 T2  V1 V2

For this formula any volume units may be used as long as they cancel, and Kelvin must be used for temperature. Remember K = OC + 273 Example: A sample of air has a volume of 140.0 mL at 67C. To what temperature must the gas be lowered to reduce its volume to 50.0 mL? Solution: Be sure to use Kelvin, not Celsius.

T1/V1 =T2/V2 T2 = T1V2/V1 = 340 K x 50 mL/140 mL = 121.4 K (that’s -151.6 oC; very cold) Reality check : Both the temp and the volume decreased nearly by a factor of 3

1. A sample of hydrogen gas has a volume of 275 mL at 25C. If the temperature is increased to 130C, what is its new volume?

2. A 35 L oxygen sample originally has a temperature of 20C. If the sample is cooled to 10C, what is its new volume?

3. A nitrogen sample at 50C occupies a volume of 800 cm3. After heating, the sample occupies a volume of 1000 cm3. What is the new temperature of the gas?

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Name: _____________________________________

Date: _____ Period: _____

WS10.3

Gay-Lussac’s Law Practice Problems Heating a sealed empty bottle is dangerous- it could explode. As the temperature of a gas increases in a closed non-expandable container, the pressure increases. Gay-Lussac wrote it mathematically:

T1 T2  P1 P2

For this formula any units of pressure may be used as long as they cancel, and the temperature must be in Kelvin (remember K = OC + 273) Example: You have a closed aluminum can that can handle a pressure of 4 atmospheres before it bursts. If this closed 2 liter can at a pressure of 1.2 atmospheres is heated from 25 degrees Celsius to 100 degrees Celsius, will it burst? Solution:

T1 T2 273 K 373 K 373 K 373 K  ;  ; 227.5  ; x atm   1.64 atm. P1 P2 1.2 atm x atm x atm 227.5 K The can will handle up to 4 atmospheres, so it will not burst.

1. Before a trip from New York to Boston, the pressure in a car tire is 1.8 atm at 20C. At the end of the trip, the pressure gauge reads 1.9 atm. What is the new Celsius temperature of the air inside the tire?

2. A sample of hydrogen at 47C exerts a pressure of 250 mm Hg. If the gas is heated to 77C at a constant volume, what will its new pressure be?

3. To what temperature must a sample of nitrogen at 300K and 0.625 atm be heated to so that its pressure becomes 1.125 atm?

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Name: _______________________________ Date: _____ Period: ______

WS10.4

Avogadroâ&#x20AC;&#x2122;s Principle: Problems A mole of an ideal gas occupies 22.4 L at STP (standard temperature and pressure: 273K, 1 atm):

22.4 L of an ideal gas = 1 mole. All of these problems are solved using this relationship: 22.4L/mol, or 1 mol/22.4 L Example: How much did the hydrogen in the Hindenburg weigh, assuming STP and a volume of 200 million liters? Solution: 200 million liters H2 x

2 g H2 mole H2 x ď&#x20AC;˝ 17.9 million g Hydrogen 22.4 liters H2 mole H2

1. Calculate the number of moles present for an ideal gas with a volume of 40 liters at STP.

2. What is the density of CO2 gas in g/L at STP? Molar mass of CO2 = 44 g/mol.

3. A gas is found to have a density of 2.595 g/L at STP. What is the molar mass of this gas in g/mol?

4. Calculate the volume that 2.0 kg of methane gas (CH4) will occupy at STP

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Name: _______________________________ Date: _____ Period: ______

WS10.5

Ideal Gas Law Problems Combining the laws or principles of Boyle, Charles, Gay-Lussac, and Avogadro provides:

PV = nRT Where

P = pressure in atmospheres V = volume in Liters n = the number of moles R = 0.0821 atmL/molK (note that R is always this number) T = temperature in Kelvin

Note that all of these units must be used- this is the most common error (see below). Here are some helpful conversions: 1 atm = 760 mm Hg = 14.7 psi 1 L = 1000 mL Tc + 273 = Tk Example: What is the temperature of 2 moles of an ideal gas at 300 mm Hg and 12 liters of volume? Solution: convert to SI units and plug into the ideal gas equation. PV = nRT; T = PV/nR = (0.395 atm)(12 L)/ (2 mol)(0.0821 atmL/molK) = 45.5 K ***Here are the most common errors:*** 1. Don’t know where to start Solution: Find out what you are given- in all cases you get 3 of the four P V n T variables- it must be an ideal gas problem. Rearrange the equation to solve for the missing one, and plug in your correct units (see #2) 2. Didn’t use Liters (L), atmospheres (atm), mole (mol), and Kelvin (K) units. Solution: use the helpful conversions above and convert to L atm mol K. 3. What do I do with grams in these problems? Solution: Convert to moles (n). If you have 16 grams of methane, then n = 1 since the molar mass of methane is 1 g/mol (12 +1+1+1+1). Similarly, if the question asks for grams, solve for n then convert moles to grams…for example if you have 9 grams of water, that is half a mole (9/18). For all of these questions please circle your answer and be sure you have included your units. 1. What is the volume (in L) occupied by 0.25 mol of oxygen at 20C and 740 mm Hg?

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2. How many moles of chlorine are contained in a 10 mL tank at 27ď&#x201A;°C and 3.5 atm of pressure?

3. What is the pressure on a 6-L system containing 32 g Oxygen gas at 45ď&#x201A;°C?

4. How many grams of Neon gas are contained in a 200-mL tank at 421ď&#x201A;°C, with a pressure of 420 mm Hg?

5. How many molecule of H2O are present in a 230-mL container, held with a temperature 485K, with a pressure 12.8 psi?

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Gas Law Worksheet Challenge Problems: 6,8,16,17 These problems include one new law: The combined gas law: P1V1/T1 = P2V2/T2 (see #8, for example)

1. In a certain experiment a sample of helium in a vacuum system was compressed at 25 °C from a volume of 200.0 mL to a volume of 0.240 mL where its pressure was found to be 30.0 mm Hg. What was the original pressure of the helium?

2. A hydrogen gas volume thermometer has a volume of 100.0 cm3 when immersed in an ice-water bath at 0 °C. When immersed in boiling liquid chlorine, the volume of the hydrogen at the same pressure is 87.2 cm3. Find the temperature of the boiling point of chlorine in °C.

3. 2.50 grams of XeF4 is introduced into an evacuated 3.00 liter container at 80.0 °C. Find the pressure in atmospheres in the container.

4. A lighter-than-air balloon is designed to rise to a height of 6 miles at which point it will be fully inflated. At that altitude the atmospheric pressure is 210 mm Hg and the temperature is -40 °C. If the full volume of the balloon is 100,000.0 L, how many kilograms of helium will be needed to inflate the balloon?

5. How many liters of pure oxygen, measured at 740 mm Hg and 24 °C, would be required to burn 1.00 g of benzene, C6H6 (l), to carbon dioxide and water? (Hint: find the moles of oxygen needed from the balanced equation, then use gas laws.)

6. Air from the prairies of North Dakota in winter contains essentially only nitrogen, oxygen, and argon. A sample of air collected at Bismarck at -22 °C and 98.90 kPa had 78.0 % N2, 21.0% O2, and 1.0% Ar. Find the partial pressures of each of these gases.

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7. For a mole of ideal gas, sketch graphs of a. P vs. V at constant T. b. P vs. T at constant V. c. V vs. T at constant P.

8. What would be the partial pressure of N2 in a container at 50 °C in which there is 0.20 mole N2 and 0.10 mole CO2 at a total pressure of 101.3 kPa?

9. What volume of Ne at one atm and 25.0 °C would have to be added to a sign having a volume of 250 mL to create a pressure of one mm Hg at that temperature?

10. Find the volume of a gas at 800.0 mm Hg and 40.0 °C if its volume at 720.0 mm Hg and 15.0 °C is 6.84 L.

11. 12.8 L of a certain gas are prepared at 100.0 kPa and -108 °C. The gas is then forced into an 855 mL cylinder in which it warms to room temperature, 22.0 °C. Find the pressure of this gas in kilopascals.

12. In a laboratory experiment, 85.3 mL of a gas are collected at 24 °C and 733 mm Hg pressure. Find the volume at STP.

13. What is the mass of 18.9 L of NH3 at 31.0 °C and 97.97 kPa?

14. 0.279 moles of O2 in a 1.85 L cylinder exert a pressure of 3.68 atm. What is the temperature in the cylinder (in °C)?

15. A quantity of potassium chlorate is selected to yield, through heating, 75.0 mL of O2 when measured at STP. If the actual temperature is 28 °C and the actual pressure is 0.894 atm, what volume of oxygen will result?

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16. A mixture of hydrocarbons contains three moles of methane, four moles of ethane, and five moles of propane. The container has a volume of 124 liters and the temperature is 22 째C. Find the partial pressures of the three gases, in kPa.

17. How many liters of H2 at 23 째C and 733 mm Hg are released by the reaction between 1.98 grams of Na and unlimited water by the following equation? 2 Na + 2 H2O -- > H2 + 2 NaOH

Answers: 1) 0.0360 mm Hg 2) -35 째C 3) 0.117 atm 4) 5.8 kg 5) 2.4 L 6) 77.1 kPa N2, 20.8 kPa O2, 9.89 kPa Ar 7) a - hyperbola, b&c - straight lines 8) 67 kPa N2, 34 kPa CO2 9) 0.329 mL 10) 6.69 L 11) 2680 kPa 12) 75.6 mL 13) 12.5 g 14) 24 째C 15) 92.5 mL 16) 59.3 kPa methane, 79.0 kPa ethane, 98.8 kPa propane 17) 1.08 L

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How to ace the Gases Test We have been observing the behavior of gases for several days. Our goal has been to determine how the physical properties of gases interrelate. To begin we created brief experiments at a series of stations where we explored the interactions of temperature, pressure, and volume within various gaseous systems. For each experiment we looked for changes in volume, pressure, ands temperature. We then compared these results to the Gas Laws of Boyle, Charles, Graham, and Gay-Lussac We also looked at a combination of these known as the ideal gas law, To ace the gases test you should be able to: 1. Describe the macroscopic (visible) properties of liquids, solids, and gases. A solid has/does not have a fixed volume and will/will not assume the shape of a container. A liquid has/does not have a fixed volume and will/will not assume the shape of a container A gas has/does not have a fixed volume and will/will not assume the shape and volume of a container 2. Accurately predict the behaviors of molecules as they undergo changes of pressure, temperature, volume, or the number of molecules. As the temperature increases in a non-expandable container like a sealed can, the _____________ increases and the __________ remains constant. As the temperature increases in an expandable container like a balloon, the _____________ increases and the __________ remains constant. As the pressure increases in a collapsible container like a syringe, the __________ decreases and the ____________ remains constant. 3. Apply the Gas Laws to predict how one physical change will affect another if the third remains constant. If the pressure increases from 100 to 200 kilopascals in a 3 liter container and the temperature remains constant, what will the final volume be? (101.7 kilopascals = 1 atmosphere). If the temperature increases from 273 to 298 Kelvin in a 25 liter balloon and the pressure remains constant, what will the final volume be? 4. Be able to convert between degrees Celsius and Kelvin. If the temperature increases from 25 to 100 degrees Celsius in a non-expandable container at 1.2 atmospheres, what will the final pressure be?

â&#x20AC;˘

5. Be able to solve gas law problems based on Avogadroâ&#x20AC;&#x2122;s Principle 2. What is the density of CO2 gas in g/L at STP? Molar mass of CO2 = 44 g/mol. 6. Be able to solve gas law problems involving multiple changes (ideal gas law) Example: How many moles of chlorine are contained in a 10 mL tank at 27ď&#x201A;°C and 3.5 atm of pressure? As a final Review, complete the activity on the following page in class. If you are doing this at home, choose your own numbers for the volume of the syringe.

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Name_________________________ Period___________

L2gasreview1

Gas Laws Review: Use the Gas Laws and Principles to solve each problem. 1. Take a 50 ml syringe, and set it to any big volume. My volume is ___ mL Push down on it hard. The new volume is ____ mL How much pressure did you apply (in atmospheres)? Show your work in the box. Circle your answer. This question is based on _________’s Law 2. Set your syringe to any volume. I have just set my syringe to ____ mL. Now warm it in your hands for 10 seconds. The new volume is _____. You warmed it from 25 OC to 37OC. What is the new volume supposed to be? If your syringe didn’t move this is probably because __________________________________________. This question is bases on ___________’s Law 3. This time I have set the syringe to _____ mL. With one hand hold the syringe so it can’t expand. Warm the syringe with the other hand. What is the new pressure in the syringe? This question is based on ____________’s Law 4. Now I am setting my syringe to ___ mL. How many moles of gas are in your syringe? (Hint: one mole of gas = 22.4L. My syringe has ____ moles of air in it. This question is based on _______________’s Principle. 5. Set your syringe to 40 mL. Push down on it until the volume is 20 mL. We can figure out the new pressure in our heads: it must be ___atm. Now warm it in your hands to 37 OC. Use this final data to figure out how many moles of gas are in the syringe. Final Volume:_____ Final Pressure:_____ Final Temperature:_____ Number of moles:_____ This question is based on the ___________ Law. 6. (L1 only; extra credit for L2). Assuming an average molecular mass of 30 g/mol, calculate the density of air in g/L using Avogadro’s Principle.

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Gas Laws Worksheet Answer Key 1. 2.

3.

4. 5. 2 C6H6 (g) + 15 O2 (g) --> 12 CO2 (g) + 6 H2O (g)

6.

7. 8. 9. 10. 11. 32


12. 13. 14. 15. 16. This can be done by a couple of methods. One possible way is:

17.

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Unit 11

Solutions Introduction: A solution is a homogenous mixture. Perhaps the best way to get an idea just how common solutions are is to go grocery shopping. There you will see virtually every type of solution, in all sorts of colors and types. This unit is primarily a roll-up-your sleeves and learn how to do things unit. Learn how to make a 25% (v/v) fruit juice solution. Dilute a chocolate solution from 20% to 8%. Find out why they salt the roads in the winter and just how much of an effect it has. How do we make and modify solutions?

Schedule: Day 1

Learn How to make rock candy; introduction to solutions

2 3

Measure density of tiny objects Theory of making, diluting, and concentrating solutions How to make and dilute solutions Why they put salt on the roads Put it all together â&#x20AC;&#x153; â&#x20AC;&#x153;

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activity Rock candy lab Intro to solutions powerpoint Flink lab Solution concentration powerpoint Making solutions activity Colligative properties Test review Solutions test

homework Ws 11.1: introduction to solutions Rock candy questions Complete lab ws ws Study for test Read next unit introduction.

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Name__________________________ Period______________ Lab11.1: Rock Candy Lab Rock Candy Lab Introduction: Have you ever noticed on television how clean the scientistâ&#x20AC;&#x2122;s labs are? How carefully they work with their solutions, their little pipettes, or even with their cadavers? Usually Hollywood hopelessly botches any attempt to portray scientists, but in this case they got it right. Good science requires pure chemicals. And to this day one of the best ways to prepare a pure solid sample is by recyrstallization- the process of isolating pure crystals from a solid/liquid solution. In this experiment you will make rock candy at home and bring it in to share with your classmates. This is an excellent example of recrystallization in action. Safety Notice: Since no food is allowed in the lab, this experiment must be performed at home. Rock Candy A video can be seen here at http://chemistry.learnhub.com/lesson/9991-rock-candy-video Prep: 15 min., Cook: 20 min., Stand: 14 days. Ingredients 1 Pie tin A clear cup 6 cups of sugar 4 wood skewers Cardboard to cover cup Masking tape

Recipe 2. Bring 2 cups of water to a boil, then add 6 cups of sugar and stir until dissolved. Measure carefully, as our experiments suggest that as little a measurement off by as little as 5% can make a huge difference in crystallization time. Add any food-grade additives you like: food coloring, cinnamon oil, vanilla, etc. 4. Fill a clear plastic cup with the hot sugar solution, cover with the cardboard, and tape shut. Stick skewers in, not touching the bottom. Let stand 10 to 14 days.

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Name_______________________________ period_________________ lab 1.1rockcandy Use any reliable sources necessary on the web to answer the following questions: 1. Draw the chemical structure of glucose, fructose, and sucrose, with their chemical formula below each structure.

glucose: formula:___________

fructose: formula:________

sucrose: formula:___________

2. Which of the above sugars is table sugar? Glucose, fructose, of sucrose?

2. It is said that a crystal resembles the structure of the molecule it is formed from. The hexagonal quartz crystals from SiO2 are an example. Since we started from sugar crystals, dissolved them in water, then let them reform slowly, the process is known as recrystallization. Based on the chemical structure of table sugar, draw a prediction of what your crystals will look like.

Predicted close-up view of a sugar crystal 4. Explain in you own words why it may a good idea to coat your string in sugar to aid in recyrstallization. The principle is known as nucleation, but please explain it without sounding like a science geek.

5. Why do we use so much sugar and so little water in this recipe? The principle is known as supersaturation, but explain it in your own words without sounding like a science teacher.

3


Name___________________________ Period____________

rockcandylabnotebook

Rock Candy Lab Notebook Please make daily notes as you observe your rock candy experiment progressing. You should include observations, comparisons to other experiments, and document any changes, such as heating, adding ventilation, or any substances added to the solution. Date

Observations

Changes made to experiment

Comparison to others

4


3. How does it happen?

What are they? Homogeneous mixtures Only one thing visible

Everywhere!

What is in a solution?

Solute(s):

dissolver mouthwash

dissolved

Is it a solution?

yes

water

no

granite

no

bronze

yes

1

Chemadventure Chapter 11: Solutions

4. How does it NOT happen?

5. Will heating or pressure help?

6. Make Crystals

A molecular view of dissolving:

7. Types 8. Measuring

3. How does it happen?

Where are they?

Solvent:

1. Where are they?

2. What are they?

Solutions

9. Making them 10. Using them

Fully dissolved salt water

Partly dissolved

Solvation:

= solvent surrounding the solute

Electrolyte: Salt. Non-Electrolyte:

Not a salt (ex: sugar)

2

9. Making them 10. Using them

2. What are they?

6. Make Crystals

7. Types 8. Measuring

1. Where are they?

5. Will heating or pressure help?

4. How does it NOT happen?

Chemadventure Chapter 11: Solutions

5


5. Will heating or pressure help?

Solubility

2. What are they?

Ethanol

CH3CH2OH

yes

Propanol

CH3CH2CH2OH

Yes

Butanol

CH3CH2CH2CH2OH

No!

Rule of thumb:

watery “like dissolves like”

3

Chemadventure Chapter 11: Solutions

4. How does it NOT happen?

5. Will heating or pressure help?

6. Make Crystals

Heating Solutions A solubility surprise:

Heating makes Most solids More Soluble Most gases Less Soluble

Global implications

4

9. Making them 10. Using them

2. What are they?

Greasy

7. Types 8. Measuring

3. How does it happen?

yes

9. Making them 10. Using them

CH3OH

1. Where are they?

Name

Greasier

Why don’t oil and water mix? Soluble in Formula water?

Methanol

1. Where are they?

6. Make Crystals 7. Types 8. Measuring

3. How does it happen?

4. How does it NOT happen?

Chemadventure Chapter 11: Solutions

6


3. How does it happen?

2. What are they? 1. Where are they? 3. How does it happen?

Is there a way to increase the solubility of ANY solution?

Yes: Henryâ&#x20AC;&#x2122;s Law

Solubility is proportional to pressure

S~P

S1/P1 = S2/P2

If sol. Is 1g/L at 1 atm, it will be 2 ______g/L at 2 atm Everyone: if solubility is 3.45 g/L at 5.6 atm, what is the solubility at 1 atm? 3.45/5.61 = S2/1

S2 = 0.614 g/L

(Henrys Law Worksheet)

5 Chemadventure Chapter 11: Solutions

4. How does it NOT happen?

5. Will heating or pressure help?

6. Make Crystals

How to make crystals:

Watch a video online here or play the flv file here or the avi file here

The process:

The principle:

recrystallization supersaturation

and cool

Or evaporate Or Reduce pressure

The process of forming the very first crystal during crystallization is called

nucleation

Fun nucleation video here

6

9. Making them 10. Using them

1. Make a hot supersaturated solution

saturated

7. Types 8. Measuring

2. What are they?

6. Make Crystals

9. Making them 10. Using them

1. Where are they?

5. Will heating or pressure help?

7. Types 8. Measuring

2.

4. How does it NOT happen?

Chemadventure Chapter 11: Solutions

7


3. How does it happen?

2. What are they? 1. Where are they?

Solutions Type Gas-gas Gas-liquid Liq-Liq Solid-liq Solid-solid

Ex. Air Soda Vinegar Ocean Fillings

Solvent N2 H2O H2O H2O Ag

solute O2 CO2

Acetic acid

salts Hg 7

Chemadventure Chapter 11: Solutions

4. How does it NOT happen?

5. Will heating or pressure help?

Concentration

10 g NaCl 90 g H2O

% by mass (% m/m) 10% NaCl by Mass

58.5 g NaCl 1L solution

Molarity (M) 1M NaCl

Mass solute x 100 Mass of solution Volume of solute x 100 Volume of solution Moles of solute Liter of solution

58.5 g NaCl 1 kg water

Molality (M) 1m NaCl L1 only

Moles of solute Kg of solvent

58.5 g NaCl 162 g H2O

Mole Fraction (X)

Moles of solute

XNaCl = 0.1

L1 only

Moles solution

8

9. Making them 10. Using them

10 mL juice % by volume (% v/v) 90 mL H2O 10% NaCl by Volume

6. Make Crystals 7. Types 8. Measuring

3. How does it happen?

6. Make Crystals

9. Making them 10. Using them

2. What are they?

5. Will heating or pressure help?

7. Types 8. Measuring

1. Where are they?

4. How does it NOT happen?

Chemadventure Chapter 11: Solutions

8


3. How does it happen?

2. What are they? 1. Where are they?

• You have a 100.5 mL solution containing 5.1 g glucose (molar mass = 180.16 g/mol). What is the molarity of that solution? • Solution • Molarity = moles of solute/L of solution • Moles solute = 5.1 g glucose x 1 mole glucose/180.16 g glucose = 0.0283 moles glucose • L of solution = 100.5 mL x 1L/1000 mL = 0.1005 L solution • Molarity = 0.0283 moles/0.1005 L solution = 0.282M Molarity ws 9 Chemadventure Chapter 11: Solutions

4. How does it NOT happen?

5. Will heating or pressure help?

Another example

6. Make Crystals

• Make 100 mL of a 1M NaOH solution

Take 4 g NaOH; add water til 100 mL.

10

9. Making them 10. Using them

1 mole NaOH 40 g NaOH x x 0.1 liter solution  4 g NaOH liter solution mole NaOH

7. Types 8. Measuring

3. How does it happen?

Molarity Examples

6. Make Crystals

9. Making them 10. Using them

2. What are they?

5. Will heating or pressure help?

7. Types 8. Measuring

1. Where are they?

4. How does it NOT happen?

Chemadventure Chapter 11: Solutions

9


3. How does it happen?

2. What are they? 1. Where are they?

• As solvent increases, concentration

decreases

• C1 V1 = C2 V2

• Concentration may be Molarity, % v/v, % mass • How can I dilute 53.4 mL of a 1.50M soln of NaCl to make it a 0.800M solution? • Easy: C1V1 = C2V2 • (1.50mol/L)(53.4mL)= (0.800mol/L)(V2) • V2 = 100. mL • (dilute to 100 mL to get 100 mL of a 0.8M soln)

11

Chemadventure Chapter 11: Solutions

4. How does it NOT happen?

5. Will heating or pressure help?

Colligative Properties

6. Make Crystals 7. Types 8. Measuring

3. How does it happen?

6. Make Crystals

9. Making them 10. Using them

L2: concepts only. (L1 all)

• How do solutes affect boiling and freezing point?

collective

Solutes elevate the boiling point Solutes lower the freezing point (road salt) 12

9. Making them 10. Using them

2. What are they?

Dilution

5. Will heating or pressure help?

7. Types 8. Measuring

1. Where are they?

4. How does it NOT happen?

Chemadventure Chapter 11: Solutions

10


3. How does it happen?

Fewer solvent molecules on surface

L1 only

x

# of ions

BP elevation constant molality

Sugar = 1 NaCl = 2 CaCl2 = 3

= moles solute/Kg solvent What is the boiling point of a 2.75m aqueous NaCl solution?

1. Where are they? 3. How does it happen?

pm

“Particle molality”

Tb =Kbm x pm Particle molality = 2 (easy to forget) • = (0.512)(2.75 x 2)= 10.22 oC • BP = 102.82 oC

13

Chemadventure Chapter 11: Solutions

4. How does it NOT happen?

5. Will heating or pressure help?

6. Make Crystals

Solutes lower freezing point

Interfere with crystal formation L1 only “Particle molality” Tf = Kfm

pm

Sugar = 1 NaCl = 2 CaCl2 = 3

constant molality = moles solute/Kg solvent What is the freezing point of a 2.75m aqueous NaCl solution?

Tf =Kfm x pm Particle molality = 2 (easy to forget) • = (1.86)(2.75 x 2)= 10.22 oC • FP = -10.22 oC 14 Next: Energy

9. Making them 10. Using them

FP depression

x

7. Types 8. Measuring

2. What are they?

6. Make Crystals

9. Making them 10. Using them

1. Where are they?

5. Will heating or pressure help?

7. Types 8. Measuring

2. What are they?

Solutes elevate boiling point

4. How does it NOT happen?

Chemadventure Chapter 11: Solutions

11


Name: _______________________________ Date: _______ Period: ______

Lab11.2

Plastic Bead Density Activity In this demonstration we will â&#x20AC;&#x153;flinkâ&#x20AC;? a plastic bead using sugar and water to determine the density of the solution. We will then use our data to determine the concentration of the solution by mass, volume, and molarity. Useful Formulas: Density = mass/volume % by Mass = (mass solute/mass solution) x 100 % by volume = (volume solute/volume solution) x 100 Molarity = M = moles solute/liters solution

Procedure: Using a test tube, water, and sugar, Make your bead hover. Keep track of exactly how many mL of water and how many grams of sugar are in your solution. 1. Data

Volume of water: _______mL Mass of water:__________g (same number since density of water is 1 g/mL) Volume of sugar: ________g Mass of sugar = _____mL (sucrose density = 1.59 g/mL). Show your calculation below: Total volume of solution: _________mL (measure using a graduated cylinder. Total mass of solution:___________g (add up mass of water and mass of sugar)

2. Calculations. Use the formulas on the first page for your calculations. You must show your work for credit. 1. Determine the density of the bead.

2. Determine the % sugar in the solution by volume.

3. Determine the % sugar in the solution by mass.

4. Determine the molarity of the sugar (C12H22O11) solution. Note that 1 mole of sugar is 338 grams

Summarize your results here for credit: Results: 1. Density of bead: ___________2. % sugar in solution by volume:_________3. % Sugar in solution by mass:___________4. Molarity of sugar solution:__________

12


Name_________________________ Period________________

ws 11.1

Talking about Solutions For some of us, when we think of a chemist we imagine some person in a lab coat mixing chemicals together. That person is preparing a solution, which is what this unit is all about. Read the paragraphs below and then use your newfound knowledge to answer the questions that follow. A solution is a homogeneous mixture, which means that only one thing is visible in the solution. The substance that is dissolved is the solute, and the substance that does the dissolving is the solvent. On a molecular scale dissolving involves the solvent surrounding the solute, and if they are salts they are divided into their ionic components- this process is known as solvation. Solutes that are salts are known as electrolytes. If the solutes are not ionic, like sugar for example, they are non-electrolytes. In general if the solute has a chemical structure similar to the solvent, it will dissolve. For this concept (solubility) it is said that “like dissolves like”. In the organic world one can identify, for example, greasy (hydrocarbon chains), watery (OH groups), and brick-like (alternating double-bonded rings like Greasy: will dissolve in benzene) groups. A “brick”: hard to

HO

greasy solvents

watery: will dissolve in dissolve in anything. watery solvents (like water)more solute to a solvent than it add

It has often been observed that one can, at least temporarily, can handle. For example, a maximum of 35.9 grams of table salt (NaCl) is soluble in 100 mL of water at 25 O C: this is a saturated solution; it has all the salt it can handle. But if you add it slowly you can get 40 or even 45 grams of salt to dissolve in water. It is now supersaturated, and the extra salt will precipitate or “crash out of solution” by doing almost anything- it is ultra-sensitive. It’s almost like the first molecule of salt needs to crystallize, but none of the molecules are volunteering. That first watery region crystal forming from a supersaturated solution is known as nucleation, and there are two ways to get a volunteer. The classic way is to add a tiny amount of solid salt (known as a seed crystal)…kind of like adding a volunteer; this is called heterogeneous nucleation. The second way is to just bump the solution, or keep waiting, and finally a molecule decides to volunteer on its own. This is hard to replicate because it is so sensitive, and is known as homogeneous nucleation. Finally, when the solute precipitates slowly this is known as recrystallization, and is a great way to make super-pure crystals. One can improve the solubility of a substance by changing the pressure or temperature of the solution. For solid solutes in a liquid solution (like salt in water), solubility usually, but doesn’t always increase with temperature. For example, more sugar will dissolve in water if you heat it up. Now consider soda, where heating soda makes it go flat. So for gases dissolved in liquids, solubility decreases as temperature increases. Globally, since more oxygen will dissolve in cold water than hot, this explains why the nutrient-rich seas are near the poles. Finally, solubility increases with pressureby selling soda in pressurized containers more carbon dioxide can be added to soda, giving it a better taste. This is known as Henry’s Law, which is our next topic. 13


Name______________________________ Period__________ WS 11.1 Intro to solutions Please read the previous page completely before answering the questions below Use the word back to define or answer the following questions Word Bank- These may not be used at all, or may be used more than once _____A. A homogeneous mixture is a _______ _____B. Excessive solute temporarily dissolved in a solvent results in _________ _____C. Adding a seed crystal results in ___________ nucleation _____D. An ionic solute in an _________ _____E. A solution only has one thing visible- it is __________ _____F. A non-ionic solute is a ____________ _____G. The dissolvER in a solution is the _______ _____H. Crystal formation with no additive is ___ nucleation. _____I. The substance that gets dissolvED in a solution is the ___. _____J. Solvent molecules surrounding the solute molecules is ____. _____K. When the first solute molecule precipitates is _____. _____L. A solution that has all the solute it can dissolve is _____. _____M. Add _______a to promote heterogeneous nucleation. _____N. dissolving a solute then crystallizing again is ______. Predict if the following solutions are soluble (S) or insoluble (I). Solute Solvent 14. methanol CH2OH Water (HOH) ethanol (CH3CH2OH) 15. naphthalene 16. methane (CH4)

1. Solution 2. Homogeneous (use twice) 3. Solvent 4. Solute 5. Solvation 6. Electrolyte 7. non-electrolyte 8. supersaturation 9. nucleation 10. heterogeneous 11. recrystallization 12. seed crystal 13. saturated

Soluble (S) or insoluble (I)?

Gasoline (CH3CH2CH2CH2CH2CH3) water

17. hexanol (CH3CH2CH2CH2CH2CH2OH) 18. Describe three ways to increase the solubility of a solute in a solution.

19. Why do whales do most of their eating in the nutrient-rich waters near the poles?

20. What is Henryâ&#x20AC;&#x2122;s Law? 14


Name: ______________________________ Period_________

WS11.2

Henry’s Law A sure-fire way to increase the solubility of any solute is to pressurize the solution. You see this in action every time you open a can or bottle of soda: as soon as you open it the pressure in the container goes down, so the solubility of the carbon dioxide in water goes down, and it precipitates as bubbles. Put another way, soda makers can dissolve more carbon dioxide in their soda by pressurizing the solution. Henry’s Law states this fact -that solubility is proportional to temperature mathematically. The formula is:

S1 S2  P1 P2 Where S1 and S2 are the initial and final solubilities, and the P’s are for pressure. Since the units cancel and are always positive, any consistent units can be used. Example: I’d like to make some super-carbonated soda. The solubility of CO2 in water at room temperature is 3.3 g CO2 per liter of solution at STP (273K, 1 atm). I’d like to triple that. How much pressure should I apply? Solution: This one you might be able to do in your head. To triple the solubility we need to triple the pressure- from 1 atmosphere to 3 atmospheres:

S1 S2 3.3 g /L 9.9 g/L (1 atm)(9.9 g/L)  ;  ; x=  3 atm P1 P2 1 atm x (3.3 g/L) 1. 0.85 g of a gas at 4.0 atm of pressure dissolves in 1.0 L of water at 298 K, how much will dissolve in 1.0 L of water at 1.0 atm of pressure at the same temperature?

2. 1.8 g of a gas at 2.5 atm of pressure dissolves in 2.0 L of Carbon Tetrachloride at 420 K. What pressure would the solution have to be at if 4.7 g of the same gas is dissolved at the same volume and temperature?

3. 4.28 g of a gas at 1.7 atm of pressure dissolves in 2.3 L of water at 527 K, how much will dissolve in 1.0 L of water at 1.0 atm of pressure at the same temperature?

15


Name_________________________ Period________________

ws 11.3

Solution Making Activity

People are making solutions all the time. A cup of tea contains about 1% caffeine by mass, for example. In this activity you will prepare and dilute several solutions. The following formulas will be helpful:

mass solute x 100 mass solution volume solute Percent solution by volume  x 100 volume solution moles of solute Molarity = M = Liters of solution Percent solution by mass 

Dilution formula:

C1V1 = C2V2 Where C = concentration. Usually in moles/liter, it can also be percent by mass, or percent by volume V = volume in liters Part one: Preparing solutions Example Deliver 250 mL of a 10% v/v fruit juice solution to your instructor. Provide your calculation and recipe below. Solution: ten percent of the solution is juice so… Calculation Recipe (.1)(250 mL) = 25 mL juice Dilute 25 mL of fruit juice to 250 mL with water. Deliver each of the following solutions up to your instructor. 1. Deliver 25 mL of a 5% v/v fruit juice solution to your instructor. Provide your calculation and recipe below. Calculation

Recipe

16


2. Deliver 20 mL of a 31% v/v fruit juice solution to your instructor. Provide your calculation and recipe below. Calculation

Recipe

Part two: Diluting solutions Example: Take ten mL of your 5% fruit juice solution from #1, dilute it to 3%, and deliver it to your instructor. Provide your calculation and recipe below. Solution: use the dilution formula to find the total volume of your diluted solution. Calculation Recipe C1V1 = C2V2 Dilute ten mL of your solution from #1 to 16.7 (5)(10) = (3)(x); x = 16.7 mL mL 4. Take 5 mL of your 31% fruit juice solution from #2, dilute it to 23%, and deliver it to your instructor. Provide your calculation and recipe below. Calculation

Recipe

Part three: Preparing solutions based on Molarity (L1 only). Example: Prepare 80 mL of an aqueous 0.5M NaCl solution. Provide your calculation and recipe below. Solution: use the Molarity formula, molar mass of NaCl, and volume of your solution to find out how many grams of salt you need. Calculation Recipe Dilute 1.6 g NaCl to 40 g NaCl 0.5 moles NaCl x x 0.08 Liters solution = 1.6 grams NaCl 80 mL with water. Liter of solution mole NaCl

5. Deliver 74 mL of a 0.7M NaCl solution to your instructor. Provide your calculation and recipe below. Calculation

Recipe

17


Name________________________ Period_________________

WS 11.4 making solutions

Making Solutions Calculations An essential skill for any scientist is the ability to make and modify solutions. To be sure your can calculate how to prepare solutions, Use the formulas below to answer each question. If you have any questions refer to worksheet 11.3 The following formulas will be helpful:

mass solute x 100 mass solution volume solute Percent solution by volume ď&#x20AC;˝ x 100 volume solution moles of solute Molarity = M = Liters of solution Percent solution by mass ď&#x20AC;˝

Dilution formula:

C1V1 = C2V2 Where C = concentration. Usually in moles/liter, it can also be percent by mass, or percent by volume V = volume in liters Type 1: Percent by mass and volume 1. How would you prepare 2 liters of a 35% m/m apple juice solution? Provide your calculation and recipe below. Calculation

Recipe

2. How would you prepare 5 mL of an aqueous 31%v/v NaCl solution? Note that the density of NaCl is 2.16 g/mL? Provide your calculation and recipe below. Calculation Recipe

3. How would you prepare a 10% fruit juice solution from concentrate for any volume? Calculation Recipe

Type 2: Concentration and dilution 4. How would you dilute 2 liters of a 35% m/m apple juice solution down to 19%? Provide your calculation and recipe below. Calculation Recipe

18


5. How would you concentrate 1 gallon of a 10%v/v chocolate milk solution up to 24%? Provide your calculation and recipe below. Calculation Recipe

Type 3: Molarity, molality, and mole fraction (L1 only) 6. How would you dilute prepare 50 liters of 2M NaOH solution? Calculation

Recipe

7. How would you prepare 3 liters of a 4m vinegar (C2H4O2 in water) solution? Provide your calculation and recipe below. Calculation Recipe

8. Bonus Question: Provide a recipe for preparing 200 mL of a 25% v/v NaCl solution, then concentrating it to 12M. Calculation Recipe

19


Name: ______________________________ Period: _____

WS11.4

Colligative Properties WS I L1 only Directions: For each of the following questions use the appropriate relationship or equation to solve the problem. 1. What are the boiling point and freezing point of a 0.625m Aqueous solution of any nonvolatile, nonelectrolyte solute?

2. What are the boiling point and freezing point of a 0.40m solution of sucrose in ethanol?

3. A lab technician determines the boiling point elevation of an aqueous solution of a nonvolatile, nonelectrolyte to be 1.12°C. What is the solutionâ&#x20AC;&#x2122;s molality?

4. A student dissolves 0.500 mol of a nonvolatile, nonelectrolyte solute in one kilogram of benzene (C6H6). What is the boiling point elevation of the resulting solution?

20


Name: _____________________________________ Period: _____

WS11.5

Colligative Properties WS II Directions: For each of the following questions use the appropriate relationship or equation to solve the problem.

1. What is the boiling point elevation and freezing point depression of a solution containing 50.0 g of glucose (C6H12O6) dissolved in 500.0 g of water?

2. What are the freezing point and boiling point of each of the following solutions? a. 2.75m NaOH in water

b. 0.586m of water in ethanol c. 1.26m of naphthalene (C10H8) in benzene

3. A rock salt (NaCl), ice, and water mixture is used to cool milk and cream to make homemade ice cream. How many grams of rock salt must be added to water to lower the freezing point 10.0째C?

4. What is the freezing point and boiling point of a solution that contains 55.4 g NaCl and 42.3 g KBr dissolved in 750.3 mL H2O?

21


How to ace the solutions unit. Solutions are ground zero in the chemical world- that’s where most of the action is. Gases are difficult to contain, or even see. Solids don’t react well because of surface area issues. Solutions, on the other hand, are easy to see, react, store, and work with. It’s no surprise, then, that solutions are all around us. In the grocery store, at the gas station, in our bodies- solutions abound. This has been predominantly a hands-on unit. Once we familiarized ourselves with the vocabulary, we learned how to prepare solutions of different concentrations, and how to change their concentration. We also learned how solutes affect the melting point and boiling point of solutions. To help you ace this unit, we begin with a story to sharpen your language skills in this unit. Then we present some situations where solutions need to be prepared and their concentrations adjusted. And we finish with a road salt example of colligative properties in action. Don’t forget to review your worksheets, PowerPoint’s, and labs before you take the solutions test. Read the story below and fill in the blanks and answer the questions as you go. The story is designed to include all of the new vocabulary and techniques you have learned. 1. Fill in the blanks to review the vocabulary used in this unit: Today I decided to make rock candy. I mixed sugar with water, so my solute is ________ and the solvent is _________, and since the resulting mixture was clear and colorless it was ______________. It took a while for the sugar to dissolve, probably because the big chunks of sugar made the molecular process of ___________ slow. I was surprised to see that this solution did not conduct electricity; apparently sugar is a _________________. I was also surprised to see how much sugar dissolved in water, sugar is highly _________________ in water. In fact I put so much sugar in that when I shook the solution it spontaneously crystallized; apparently the solution was __________________. Since I didn’t add a seed crystal to the solution, this is specifically known as _______________ _______________. It was cool watching the first crystal form, that moment known as ___________________. I took one of my recrystallized sugar crystals and placed it under an atomic force microscope. I could see numerous O-H groups, which reminded me of water. I can see why the saying “__________ ___________ __________” is used to predict solute-solvent solubilities. I would predict sugar to be ___________ in hexane (CH3CH2CH2CH2CH2CH3), and ____________ in ethanol (CH3CH2OH). To increase that solubility, I could _____________, _____________, or add more _____________, although one of these doesn’t always work (__________________). I know that in the cases of gases, dissolved in liquids, solubility increases when the solution is _______________. And pressurizing a solution to dissolve more solute is an example of __________ __________ in action. 2. Henry’s Law: Solubility is proportional to _____________. If the solubility of a solute in water is 2.8 g/L at 1 atmosphere pressure, and the pressure is increased to 3 atmospheres, the solubility will increase to ________ g/L. 22


3. Concentration and dilution For all of these questions you have 29 grams of table salt in 500 mL of solution. a. Describe how to prepare this solution

b. Calculate the percent salt by mass (water has a density of 1 g/mL)

c. Calculate the percent mass by volume (table salt has a density of 2.16 g/mL)

d. Calculate the molarity of the solution (table salt has a molar mass of about 58 g/mol)

e. This solution will have a (higher/lower) boiling point than pure water, and a (higher/lower) freezing point than pure water.

f. Calculate the molality of the solution (L1 only; assume 950 g water).

g. Calculate the freezing point of this solution (L1 only; Kf H2O = 1.86 OC/m; use data above for molality).

h. Calculate the boiling point elevation of this solution (L1 only; Kb H2O = 0.512 OC/m; use data above for molality).

23


1. Intro 2. data 3. matter 4. the atom 5. electrons 6. periodic table 7. bonding 8. reactions 9. the mole 10. gases 11. solutions 12. Energy 13. Reaction rates 14. equilibrium 15. Acids and bases

Energy

What changes should we make?

Many believe that man’s insatiable energy appetite is destroying the planet. In this unit we will therefore look not only at energy from a chemical perspective, but also from an environmental one. We’d like to know: 

Which energy sources are practical, abundant, and environmentally clean?

Which energy sources for vehicles are likely to replace gasoline?

Which is cheaper, gasoline or electricity?

How can energy transfer be measured?

How much energy is in a potato chip?

How much energy is involved during a phase change?

What units are used in energy and how do they relate?

What are enthalpy, free energy, and entropy, and why are they important? Tentative Schedule:

Day 1: Specific Heat

Homework: energyws2: Specific Heat

Lab: Specific Heat Capacity of a Metal Day 2: Introduction to Energy Lesson: Why Energy Matters; Definitions; Units Homework: energyws1: Energy Sources and Conversions

Homework: energyws3: Energy with phase change Day 6: Free Energy Lesson: Free Energy; Energy in Connecticut Homework: energyws4 and ws5: Phase

Day 3: How much energy is in a potato chip:

change II, Free Energy

Enthalpy

Day 7: Review

Lab: Potato Chip Calorimetry

Lesson: How to Ace the Energy Test

Homework: Complete chip lab

Homework: Review for Energy Test

Day 5: Enthalpy

Day 8: Energy Test

Lesson: Enthalpy of vaporization and fusion 1


Students: Please read this article and then answer the 2 questions at the end. Electric Cars Offer Energy Independence By Jeff Swicord Washington

09 October 2008 With fuel prices still high, the electric car is becoming a more attractive form of transportation. Electric cars were first introduced in the 1970s, but the technology has dramatically improved in the last 10 years. By 2010 automakers like Mercedes and General Motors plan to bring their models to showrooms. Jeff Swicord introduces us to one man who uses electric cars built several years ago as his primary mode of transportation. Like many people in the Washington D.C. area, Brian Murtha commutes five days a week, to downtown and back. But, he does it in an electric car. Brian owns two factory-made electric vehicles: a Toyota Rav 4 EV and a Ford Ranger pick-up truck EV. These were produced in small numbers a few years ago. He charges them from electricity produced by solar panels on the roof of his house. "After I retired from the Air Force, I set a goal not to use energy from anyone else off my property," Brian explained. "To make all my energy myself and be energy independent." Major automakers are betting there will be more and more consumers like Brian in the future. Toyota, General Motors, and Mercedes plan to have an electric vehicle in showrooms within two years. The American made Chevy Volt prototype has received widespread attention at auto shows. For now, fans of electric vehicles like Brian buy their electric cars on eBay. He paid $40,000 for the Toyota. "It gives you 900 pounds on the lowest point of the car, which makes the center of gravity better than the gasoline version," Brian said. "Which makes roll-over less likely and gives you better handling." The inside, with a few exceptions, looks like a gasoline-powered car. Murtha's sun powered car "The electric motor is actually air cooled and produces so little heat it is not really of use in the winter time for heating the passenger cabin. So, Toyota put a heat pump in there," Brian explained. He charges his cars in the garage by plugging into receptors. The electricity runs along wires that are connected to the solar panels on his roof. "It charges about 25 percent an hour," he said. "So if you ran it down a quarter on the fuel gauge, 2


if you were three quarters and you wanted to fill it all the way up, it would take you an hour." Brian says driving to work with a gasoline powered vehicle would cost him about $8 a day in fuel. "With the electric car it's about 20 to 25 kilowatt hours to go in and back," he said. "And say about .10 a kilowatt hour, that's about $3.00. And there really is not any maintenance."

His quest for energy independence includes his house. He has replaced appliances that run on natural gas with electric ones, including the furnace. But his solar array is not big enough to power the entire house and two cars.

"Well If I didn't have the electric vehicles to refuel, the 2200 watt array on the roof of my house, right now, almost completely powers the house," Brian said.

Brian plans to add another 7,000 watt array on top of his garage. It will give him more than 9,000, and that will be more power than he needs. Questions: 1. One passage in the text states “Brian says driving to work with a gasoline powered vehicle would cost him about $8 a day in fuel. “ With gas currently at 2 dollars per gallon ($2/gallon), and assuming a gasoline powered vehicle gets 30 miles per gallon (30 miles/gallon), how long is Brian’s round trip commute?

2. Another passage states “With the electric car it's about 20 to 25 kilowatt hours (kwh) to go in and back," he said. "And say about .10 a kilowatt hour, that's about $3.00.” Based on Brian’s commute from #1, what is the fuel economy of his electric car in kwh/mile?

3. Soon people will have to try to compare gas mileage to electric car mileage. Perhaps the best way would be to calculate the dollars per mile it costs to drive each car. Using the information above, determine what is cheaper to drive by calculating the A. dollars/mile cost of driving a 30 mile per gallon gasoline car at $2/gallon, and

B. the dollar/mile cost to drive a 25 kwh/mile electric car car at $.10/kwh

The cheaper car to drive is______________

3


Energy

units

diets

Specific heat

enthalpy

Welcome to planet earth. Please choose your primary energy source

#2

#3

#4

#5

Medium?

All items $1

Free energy

Cost

types

#1

Water, ice, and steam

Deluxe Meals:

(to the Planet): oil

Eco-cars

issues

coal

biomass

wood

Specials: Chemical reaction:

Nuclear fission

+ 1n

$$high

All based on C,H  CO2 + H2O

Chemical reaction:

235U

236U

Nuclear fusion

140Xe +

94Sr

+

3H

21n

+ 1H 4He

ValueMenu Chemical reaction: none

wave

wind

solar

geothermal

Hess’s Law

sources

Natural gas

hydro

Place your order:

Energy: What Changes Should We Make?

Energy

units

diets

Specific heat

enthalpy

types

Please choose your ecofriendly car

Tesla roadster

Toyota Prius

Chevy Volt

Honda Civic GX

issues

Appearance (1-10) fuel

electric

gas

Electric or gas

CH4

availability

100 now

now

2010

now

$100K

30K

30k

30k

cost

Please rate from 1-10:

BMW hydrogen 7

Honda FCX Clarity

BYD F3DM

Free energy

Eco-cars

Overall (1-10)

Venturi astrolab or eclectic

availability cost

H2

H2

Electric or gas

Electric or solar

unknown

Limited now

Now (china)

?

alot

40k

30k

?

Overall (1-10)

Also: E-85 fuel

biodiesel

Hess’s Law

sources

Appearance (1-10) fuel

Water, ice, and steam

Welcome to planet earth

My eco-friendly car choice:________

Energy: What Changes Should We Make?

4


Why the energy unit matters: units

Specific heat

enthalpy

Primary sources of energy are usually chemical nuclear

propane

Natural gas

gasoline

smog

Ozone urban sprawl depletion overpopulation global warming deforestation

pollution

Hessâ&#x20AC;&#x2122;s Law

sources

Free energy

Eco-cars

issues

coal

diets

Water, ice, and steam

types

Energy

Energy: What Changes Should We Make? Energy

units

diets

Specific heat

enthalpy

types

If I eat normal, and run hard one hour per day I should 500 lose _____Nutritional Calories per day

1,000 One hour of intense cardio exercise burns ______ Nutritional Calories

1 And I can expect to lose ____ pound(s) per week.

Hessâ&#x20AC;&#x2122;s Law

3,500 Nutritional Calories One pound of body fat contains _____

Free energy

Eco-cars

1,500 Nutritional Calories per day People burn roughly _____ without exercise

sources

issues

2,000 An average diet is about _____ Nutritional Calories per day

Water, ice, and steam

Energy and Weight Loss

Energy: What Changes Should We Make?

5


issues Eco-cars

diets

Specific heat

enthalpy

Specific heat: The amount of heat necessary to heat one g of water by one OC. Q = mcT heat Mass (g)

Temp. change oC

c = Specific heat constant = 4.184 j/g oC for water

Q = mcT

= (237)(4.184)(75) = 74,371 joules

Hess’s Law

How many joules of heat are needed to heat one cup (237 mL) of water from room temp. (25 oC) to boiling (100 oC)?

Free energy

sources

units

Water, ice, and steam

types

Energy

Energy: What Changes Should We Make?

6


issues Eco-cars

diets

Specific heat

Enthalpy

enthalpy

H

• = heat change at constant

pressure

+

-

Hess’s Law

• =H or Hrxn Q H vs. q? H = q when pressure is constant • Endothermic • Exothermic Reactions Reactions H is positive H is negative

Free energy

sources

units

Water, ice, and steam

types

Energy

Energy: What Changes Should We Make?

issues

diets

Specific heat

enthalpy

5. Standard Enthalpies of Vaporization and Fusion. For water:

• H2O(l)H2O(g) Hovap = 2260J/g

gas 2260 J/g

• H2O(s)H2O(l) Hofus = 334 J/g

Hcond

Hvap

-2260 J/g

334 J/g

Hfus

Hsolid -2260 J/g solid

Hess’s Law

sources

liquid

Free energy

Eco-cars

units

Water, ice, and steam

types

Energy

Energy: What Changes Should We Make?

7


units

diets

Specific heat

Gibb’s Free Energy (j)

Josiah Gibbs New Haven, CT

Entropy (j/K)

Enthalpy (j)

What is Entropy??

Hess’s Law

sources

If G < 0 we have a spontaneous process

Free energy

Eco-cars

issues

Free G =H-TS Energy

enthalpy

Water, ice, and steam

types

Energy

Energy: What Changes Should We Make?

8


Specific heat

enthalpy

Entropy = randomness

The big bang

Hess’s Law

S = positive = more random • Liquid  gas • + more random • Liquid  solid • - less random • 1 particle  2 particles • + more random

Energy: What Changes Should We Make?

issues

diets

Specific heat

For a reaction: H=145,000 J S = 322 j/K T= 382K

enthalpy

Is it spontaneous? (Apply G =H-TS)

Hess’s Law

G =H-TS • =145,000 – 382(322) • = 22,000 • Positive: nonspontaneous.

Free energy

Eco-cars

units

Water, ice, and steam

types

Energy

sources

issues Eco-cars

diets

Free energy

sources

units

Water, ice, and steam

types

Energy

Energy: What Changes Should We Make?

9


spontaneity

issues Eco-cars

diets

Specific heat

enthalpy

S

Spontaneous?

+ + -

+ + -

always never Rarely. Depends on T Usually Depends on T

Hess’s Law

H

Free energy

sources

units

Water, ice, and steam

types

Energy

Energy: What Changes Should We Make?

10


lab16.1 Name__________________________________Period________________Date______ Specific Heat Capacity of a Metal 10 Points Please read and complete this pre-lab prior to performing this experiment. Purpose: To use a calorimeter to find the specific heat capacity of a metal. 

Theory: Have you observed how some metals stay hot longer than others? Specific heat measures this property: it is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius. For example, as a 1 g slug of hot lead (Pb) cools in water, it releases 0.129 joules (j) of heat to the water for each degree that it cools. We can therefore identify metals by measuring the specific heat of an unknown metal, and comparing it to known values. We will do this by heating a metal to 100 OC, then placing it in room temperature water to see how much hotter the water gets. Metals with a high specific heat will heat up the water a lot. We will then calculate the specific heat (called “c”) of the metal to identify it.

Questions:

1. Give a definition of specific heat in your own words- don’t use the definition above.

2. Why might it be important to use a large mass of metal for these measurements?

Procedure: We need 5 pieces of data. Put water in a calorimeter (a Styrofoam cup) to just cover your metal; mass the water. Mass of water in calorimeter: Take the temperature of the water.

Initial calorimeter water temperature:

Take the temperature of the boiling water (it should be 100 OC) Temperature of metal in boiling water: Carefully put your metal in boiling water. Wait 3 minutes. Transfer to calorimeter (cup). See how hot the water gets Temperature of water in cup (and metal) after heated by metal: Dry your metal and mass it.

Mass of dry metal:

11


Calculations q = m x c x T where q = heat change, c = specific heat, m = mass in grams, and T = change in temperature in oC. . The key assumption we will use is that heat absorbed by water = heat released by metal (qwater = qmetal). q for water = 4.184 j/goC. Solve for c and use this to identify your unknown metal. The sample calculation below should be very helpful. Sample Calculation: 125 g water, initial temperature of water = 25.6 oC, initial temperature of metal = 115.0 oC, Final temp of water = 29.3 0C. Mass of metal = 50.0 g. What is the metal? qwater = mwater x cwater x Twater = 125 g x 4.184 J/g oC x (29.3 oC – 25.6 oC) qwater = 1900J qwater = qmetal qmetal = 1900J = mmetal x cmetal x Tmetal cmetal = 1900J/m x T = 1900J/50.0 g x (115 oC – 29.3 oC) = 0.44 J/g oC. Comparing to known values, the metal may be Iron (Fe, c = 0.449 J/g oC). Question: 1. What is the identity of your unknown metal? Show your specific heat calculations below. If more than one metal was identified, use common sense to rule out dangerous or expensive elements. Since this calculation is trickier than most, a guide is presented below based on the following logic. We’d like to plug directly into q = mcT, but there are 2 unknowns- q and T. However, since the specific heat of liquid water is known we can calculate the heat gained by the water…which, if you think about it, is exactly equal to the heat lost by the metal, since that’s what heated the water. So… qwater = mwater x cwater x Twater = ____g x 4.184 J/g oC x (___ oC – ____ oC) qwater = qmetal =_____ J

rearranging, cmetal 

qmetal

mmetal Tmetal

(___ j) (___ g)(___ C) o

 ____ j g oC

By comparing this specific heat to known values, and looking at my metal, I conclude the metal is _________. 12


Name _______________________________ Period ________ Potato Chip Calorimetry

energy lab 2

In this experiment we will burn a snack chip and see how many calories of heat it produces. We will then compare it to the nutritional information on the container. We can find how many calories are contained in any combustible material by simply measuring the ability of the burning material to heat water. For every degree it can heat up a milliliter of water that is equal to exactly 1 calorie of heat energy. It is also equal to 4.184 joules, or 0.001 Nutritional Calories. To do this we put a burning chip under a beaker of water and measure how much warmer the water gets. This is known as calorimetry. The problem: Every year we perform this experiment we get lousy results. The reason: The transfer of heat from a burning chip is inefficient. Too much heat is lost to the air, and to the beaker. We’d like all of the energy from that flame to heat up the water, with no loss. It’s a similar problem to that faced at home with your furnace, or to the design of a woodstove. Let’s improve it. Draw and describe below a calorimetry apparatus that will be as efficient as possible, while still being safe. Don’t forget that your chip needs oxygen to burn, and that your design must be safe. Draw it, and describe it fully below; your homework assignment for tonight is to build your design and bring it to class tomorrow. Note that no construction will be allowed in class. Most common errors Possible solutions -nice design but chip won’t burn- not enough air pull air through or open up design -too much water- very little temperature change use less than 5 mL of water -heat loss. insulate Calorimeter Design Blueprint

13


Safety Warning: This lab includes flames, burning materials, and potentially hot water. Wear goggles, gloves, aprons, and covered shoes. It can also get smoky. Working in the hood or near a window is a good idea. Be cautious working with burning materials. Please let me know if you need fresh air. Enter your data here: Observations of the Burning of a Potato Chip ______Mass of water in beaker (For water mass = volume) ______Initial temperature of water ______Highest temperature of water ______Change in temperature 4.184__ Specific heat of liquid water in J/gOC 4,184__ Number of joules in a nutritional calorie Calculate the number of nutritional calories in your chip below; show your work including cancelled units for credit Measured Chip Calories Calculation (5 points):

Read the nutritional information on the bag and calculate the actual number of nutritional calories in your chip below. Show your work including cancelled units, and explain any estimations you had to make. Actual Chip Calories Calculation (5 points):

Why is the measured chip calories different from the actual chip calories? Provide a thoughtful explanation paragraph based on your experimental design and performance.

Explanation of results (5 points):

14


Write up this lab the in the form of a poster that follows the format shown below:

Title Name, Date

Data Q = mcď &#x201E;T Q= M= C= ď &#x201E;T = =( )( )( ) = ___ J = ___Nutritional Calories

(For example: Potato Chip Calorimetry Or Energy Analysis of a common Snack Food) Schematic drawing With labels Of your calorimeter

caption

Conclusions Include the Nutritional Calories calculated for your chip, the estimated real nutritional calories for your chip, and an explanation for the difference.

Pick a topic: 1. What is calorimetry? 2. Sources of Error in our calorimeter design 3. A better design for the next experiment 10 points: 1. Effort: 5 points -does this represent 45 minutes of effort? 2. Calculations: 3 Points -are they accurate? 3. Analysis: 2 points: Why are the results so bad (or so good).

15


Name________________________Period________

energy ws1

Energy: Sources, definitions, and conversions Many people, including scientists, believe the Earth, and the people on it, are in trouble. Problems include global warming, air, land, and water pollution, ozone depletion, overpopulation, and urban sprawl, among others. People may disagree as to how serious these issues are, but most would agree that many of the problems relate to energy use. Here we will consider what energy is, how we use it, and how we measure it. Energy is defined as the ability to do work or produce heat. Our primary sources of energy are the combustion of fossil fuels, nuclear fission, and more passive sources including solar, wind, and geothermal energy. Currently, fossil fuels and the nuclear fission of uranium-235 provide most of our energy needs. In Connecticut, about 50% of our electrical energy comes from nuclear fission, 40% from burning oil, gas, biomass, and coal, and the rest is from solar, wind, geothermal, and other sources. Energy is measured using a variety of units. A Nutritional Calorie is one most of us are familiar with. Not to be confused with the scientific calorie, (note the small c), a Nutritional Calorie is the amount of energy required to raise the temperature of a liter of water by one degree Celsius. Unfortunately, lots of different energy units are used, so we need to be familiar with them and know how to convert them. Here are the most common ones: 1 Nutritional Calorie = 4 BTU (British Thermal Units) = 1000 calories = 4184 joules = 0.0016 KWH Use this information above to answer the following questions 1. What is the primary source of energy that powers your rechargeable ipod? a. The battery b. The electrical outlet c. Sunlight d. Power Plants e. Power lines 2. What is the primary source of energy that heats this school? a. Power lines b. Oil c. Natural Gas d. Nuclear energy d. Solar energy e. Radiators 3. What is the primary source of energy that heat our Bunsen burners in class? a. gasoline b. propane c. natural gas d. power plants e. The gas jets 4. Electrical energy in Connecticut comes from a. Electrical outlets b. Power lines c. Nuclear power d. Nuclear power and combustion e. solar energy 5. What is energy? 6. What do you believe is the primary cause of global warming?

16


7. How much energy is required to heat a liter of water from 25 OC to 27 OC? Please show your calculation including cancelled units.

8. You just ate a chocolate bar, which will provide your body with 300 Nutritional Calories of sugarrush energy. Please show your calculation including cancelled units. Convert this 300 Nutritional Calories to a. Joules (Hint: there are 4184 joules in a Nutritional Calorie)

b. British Thermal Units (btu)

c. kilowatt hours (KWH) 9. Here is the calculation that tells me I should buy a plug-in hybrid car as soon as they come out: My gas-powered Mazda gets 30 miles per gallon (thatâ&#x20AC;&#x2122;s 30 miles/gallon), and gas currently costs $3.20 per gallon. How much does it cost to drive my Mazda one mile?

Each mile driven by a Toyota Prius uses 0.25 kilowatt hours of electrical energy when the combustion engine is off (thatâ&#x20AC;&#x2122;s 1 mile/0.253 kwh) and the electricity costs 10 cents per kwh. How much does it cost to drive the Prius one mile?

Which is cheaper to drive- the Mazda, or the Toyota?

17


Name________________________Period________

energy ws2

Specific Heat Worksheet Have you ever noticed how some substances feel colder than others in a room? Or have you noticed that some metals like iron retain their heat for a long time, while others like aluminum cool very quickly? Clearly, substances vary in their responses to heating and cooling. The amount of energy needed to heat a substance is known as specific heat, and is unique for each pure substance. The units are j/gOC, which literally means the amount of energy in joules needed to raise the temperature of one gram of the substance one degree Celsius. Liquid water requires over 4.184 joules, while gold only requires about 1/10 of a joule for each gram to get one degree Celsius hotter. Use the specific heat formula below to learn about the thermal properties of various substances. The first problem is solved for you. The answers are given; you must show the work to get there. All of these problems may be solved using the specific heat equation: q = mcT where q = heat in joules m= the mass of the substance in g c = the specific heat of the substance in j/goC (2.03 for ice, 4.184 for liquid water, and 2.01 for steam) And T is the absolute temperature change in oC. Example: How much energy must be absorbed by 20.0 g of liquid water (Cwater = 4.184 j/g0C) to increase its temperature from 283.0 °C to 303.0 °C? Solution: q = mcT = (20.0 g)(4.184 J/g0C)(20 oC) = 1,673.6 J

1. When 15.0 g of steam drops in temperature from 275.0 °C to 250.0 °C, how much heat energy is released?

°

°

2. How much energy is required to heat 120.00 g of water from 2.0000 C to 24.000 C?

(754 J)

(11,046 J) 3. If 720.0 g of steam at 400.0 °C absorbs 800.0 joules of heat energy, what will be its increase in temperature?

(400.6 OC) 18


4. How much heat (in J) is given out when 85.0 g of lead cools from 200.0 °C to 10.0 °C? (Clead = 0.129 J/g °C) (2080 J) ° ° 5. If it takes 41.72 joules to heat a piece of gold weighing 18.69 g from 10.0 C to 27.0 C, what is the specific heat of the gold?

(0.131 J/gOC) 6. If 35 g of a substance absorbs 4000 J of heat when the temperature rises from 25 to 5100C, what is the specific heat of that substance?

(0.235 J/gOC) 7. A certain mass of water was heated with 41,840 Joules, raising its temperature from 22.0 °C to 28.5 °C. Find the mass of water.

(1540 g) 8. Calculate the number of joules given off when 32.0 grams of steam cools from 90 degrees celsius to 31 degrees celsius.

(3800 J) 9. How many joules of heat are lost by 3580 kilograms of granite as it cools from 41.2 C to -12.9 O C? The specific heat of granite is 0.803 J/gOC O

(1.56 x 108 J) 10. In reality we are making a lot of assumptions for these calculations to be accurate. For example, in many cases we are assuming a perfectly insulated container. List two other assumptions we are making in these calculations. 1. 2.

19


Name____________________________________________ Period__________ energy ws3 Energy of Heating and Cooling Water

In the previous worksheet we learned to use the specific heat equation:

q = mcT

(where q = joules of heat, m = grams of mass, c = specific heat in j/gOC, and T = degrees of temperature change) To heat or cool water we have to consider the phase it is in, as well as the energy associated with phase changes Symbol and value Symbol What it means o The specific heat of liquid water It takes 4.18 joules of heat cwater(l) = 4.18 J/g C energy to raise the temperature of 1 gram of liquid water by one degree Celsius o The specific heat of ice It takes 2.03 joules of heat cwater(s) = 2.03 J/g C energy to raise the temperature of 1 gram of solid water (ice) by one degree Celsius o The specific heat of steam It takes 2.01 joules of heat cwater(g) = 2.01 J/g C energy to raise the temperature of 1 gram of gaseous water (steam) by one degree Celsius Hvap = 2,259 J/g The enthalpy of vaporization of It takes 2,259 joules of water energy to boil one gram of liquid water (convert it from a liquid to a gas). Hfus =334 J/g The enthalpy of fusion of water It takes 334 joules of energy to melt one gram of liquid water (convert it from a solid to a liquid). To find out how much energy it takes to heat water, we may have to include the energy of phase changes. For example, there are five separate energy steps involved when ice is heated into steam: 1. The ice warms to 0OC 2. The ice melts at 0OC 3. The water heats to 100OC 4. The water boils at 100OC. 5. The steam raises to it’s final temperature. Note for the last step we assume a closed system that would pressurize. Use these ideas to answer the guided questions below. 20


1)

A 12 oz. can of soda contains 450 g of water. How many joules are released when a can of

soda is cooled from 25 degrees Celsius (room temperature) to 4 degrees Celsius (the temperature of a refrigerator). The specific heat of liquid water is 4.18 J / gram x oC. Hint: q=mcT (39.5kJ, or 39,500 J) 2)

How many joules are required to heat 250 grams of liquid water from 00 to 1000 C ? Hint: q=mcT (104.5 kJ)

3)

How many joules are required to melt 100 grams of water? The heat of fusion of water is

6010 J / mole. Hint: Each mole we melt consumes 6010 J. How many moles of water do we have? (33.4 kJ) 4)

How many joules are required to boil 150 grams of water? The heat of vaporization of

water is 40,670 J / mole. Hint: Each mole we boil consumes 40,670 J. How many moles of water do we have? (338.8 kJ) 5)

How many joules are required to heat 200 grams of water from 25 0C to 125 0C? The

specific heat of steam is 2.01 J / g

. 0

C (Hint: there are 3 parts to this)

Hint: Here are the parts Part 1: 25-1000C: q = mcT = (

)(

)(

)=_______

Part 2: boiling at 100oC: 40,670J/mole . ______moles = ______ Part 3: 100-1250C: q = mcT = (

)(

)(

) =_______

Total = 1 + 2 + 3 =________ + _________ + _______ +_______ (524.7 kJ) 7. How much heat is required to warm 225 g of ice from -46.8°C to 0.0°C, melt the ice, warm the water from 0.0°C to 100.0°C, boil the water, and heat the steam to 173.0°C?

(732 kJ)

21


Name_____________________________________ Period________

energy ws4

Energy with Phase change WS II Useful information (see previous worksheet and powerpoint presentation for a full explanation of terms):

q = mcT

cwater(l) = the specific heat of liquid water = 4.184 J/goC cwater(s) = the specific heat of ice = 2.03 J/goC cwater(g) = the specific heat of steam = 2.01 J/goC

Hvap the energy required to convert liquid water to steam = 2259 J/g Hfus = the energy required to convert ice to liquid water = 334 J/g

Example: How many joules of energy are required to heat 25 grams of water from -28 to +130oC? Solution: Heating up that 25 grams of ice involves 5 separate steps: 1. The ice heats from -28 OC to 0OC: q = mcT = (25 g)(2.03 J/gOC)(28OC) = 1,421 J 2. At 0OC the ice melts: 334 j/g x 25 g = 8350 J 3. The water then heats from 0 to 100 OC: q = mcT = (25 g)(4.18 J/gOC)(100OC) = 10,450 J 4. The water boils at 100 OC: 2259 J/g x 25 g = 56,475 J 5. The steam heats from 100 to 185 (in reality this could only happen as pressure increases); q= mcT = (25)(2.01)(85) = 4271 J Total: 80,967 J

1)

How many joules are required to heat 75 grams of water from -85 0C to 1850C?

2)

How many joules are required to heat a frozen can of ice (360 grams) from -5 0 C (the

temperature of an overcooled refrigerator) to 110 0C (the highest practical temperature within a microwave oven)?

22


3) (Level 1 only)

How many joules are released when 450 grams of water are cooled from 4 x 107

0

C (the hottest temperature ever achieved by man) to 1 x 10-9 0C (the coldest temperature achieved

by man).

4) (Level 1 only) How many joules are required to raise the temperature of 100 grams of water 0 from -269 C (the current temperature of space) to 1.6 x 1015 0C (the estimated temperature of space immediately after the big bang)?

23


Energy ws5 Name________________________Date_________________Period____________ Free Energy Worksheet

G = H –TS Where G = Gibbs Free Energy

We have just learned that if the free energy (G) of a reaction is negative, that reaction will occur spontaneously. This can be calculated using the Gibbs Free Energy Equation shown on the left, named after New Haven’s own J. Willard Gibbs.

Now, usually a reaction is spontaneous if it is exothermic. Bang. Sometimes however, an endothermic reaction can be spontaneous. The melting of ice is a good example. H is slightly positive, but it has T = Temperature (K) something else going for it: the process produces disorder. This provides enough boost to make the reaction spontaneous at room And S = Entropy in Joules/K temperature. This randomness factor is called entropy (S). Examples of increased randomness include a liquid becoming a gas, something splitting in two, or things spreading out, like the expansion of the universe. As Entropy increases it becomes more positive. If we know the temperature, enthalpy, and entropy of a reaction or system we can use the Gibbs Free energy equation to predict if the reaction will be spontaneous.

H = Enthalpy in Joules

Example: Calculate DG and indicate if the reaction is spontaneous when H = 2.3 kJ, T = 25OC, and S = 195 J/K Solution: Note that we need to convert kilojoules (kJ) to joules (1000 J = 1 kJ), and degrees Celsius to Kelvin (K = OC + 273). G = H-TS = 2300 J – (298 K . 195 J/K) = -55,810 J = spontaneous Most common errors: Did not change kJ to J; did not change multiplying.

O

C to K; subtracting before

Calculate G and indicate if the process is spontaneous or nonspontaneous 1. H = 145 kJ, T = 293K, S = 195 J/K

24


2. H = -232 kJ, T = 273K, S = 138 J/K

3. H = -15.9 kJ, T = 100 oC, S = -268 J/K

4. Calculate the temperature at which G = 34.7 kJ if H = 40.2 kJ and S = 22.2 J/K.

Iron ore can be converted to iron by the following reaction: Fe3O4(s) + 4H2(g)  3Fe(s) + 4H2O(g) H = 149.8 kJ For this reaction S = 610 J/K. 5. Is this reaction spontaneous at 298K? What is the value of G?

6. Why is the entropy for this reaction positive?

25


How to ace the Energy exam In this our 12th unit we investigated Energy, both from a scientific and environmental perspective. We began by considering the primary sources of energy we use, and their environmental consequences, as well as their abundance. This is perhaps the most important information to answer our essential question for this unit: What Changes Should We Make? We looked at some efforts to answer this question in the form of transportation when we took a look at some eco-friendly cars. We then focused on the hard science that relates to energy: what it is, types of energy, Enthalpy, and exothermic and endothermic chemical reactions. During this time we performed two experiments where we measured the specific heat of an unknown metal, and the energy contained in a potato chip, using a calorimeter of our own design. We finished by considering the energy required to heat water, including the phase changes that may be involved, and we familiarized ourselves with Free energy, which includes the esoteric concept of entropy. To ace this unit be familiar with the terminology associated with energy, know how to measure it, and think about the sources of energy we use, and what changes we must make for the sake of our planet. As usual, review your notes, worksheets, and lab experiments, and answer all of the questions below. In our next unit we will ask why some reactions such as explosions are rapid, while others such as rust are slow- this is our Rates of Reaction unit, coming up. Useful information to be provided on test: q = mcT where m = mass (g), c = specific heat (J/g0C; see examples for H2O below), and T = change in temperature (0C) cwater(l) = 4.18 J/goC cwater(s) = 2.03 J/goC cwater(g) = 2.01 J/goC Hvap = 2260 J/g Hfus = 334 J/g At 1 atm: Water boils/condenses at 100oC Water melts/freezes at 0oC 1 Nutritional Calorie = 4 BTU (British Thermal Units) = 1000 calories = 4184 joules = 0.0016 KWH G = H-TS Where G = change in free energy (J), H = change in enthalpy (J), T = temperature (K), and S = change in entropy (J/K)

26


1. Know the meaning and usage of the following terms Energy Enthalpy (H) Potential Energy Kinetic Energy Exothermic Endothermic Specific Heat Heat of vaporization (Hvap) Heat of fusion (Hfus) Heat of condensation (Hcond) Heat of solidification (Hsolid) Hess’s Law calorie Nutritional Calorie Joule Standard enthalpy of formation (Ho) Free Energy Entropy

2. Understand concepts, with sample questions: 1. Energy Which of the following are exothermic processes: melting, freezing, boiling, condensing, subliming, depositing? 2. Thermochemical properties of fuels

27


Based on the table below, how much heat would be generated if 92 grams of ethanol were burned?

3. Energy unit conversions Convert 1000 joules to kJ, calories, and Nutritional Calories 4. Specific heat 2. When 15.0 g of steam drops in temperature from 275.0 째C to 250.0 째C, how much heat energy is released?

5. Typical specific heat numbers and their meaning 6. If it takes 41.72 joules to heat a piece of gold weighing 18.69 g from 10.0 째C to 27.0 째 C, what is the specific heat of the gold?

6. Enthalpy for temperature changes compared to phase changes. Calculate how much energy is required to convert 1 kg of ice at -10 oC to steam at 101 o C. 1. 2. 3. 4. 5. Answer:

28


7. Free Energy 1. Calculate G and indicate if the process is spontaneous or nonspontaneous a. H = 145 kJ, T = 100 0C, S = 195 J/K

b. 2. Calculate the temperature at which G = 34.7 kJ if H = 40.2 kJ and S = 22.2 J/K. 8. Energy and the Environment a. Describe details concerning the energy usage of two of your favorite eco-friendly cars

b. How can the energy costs of an electric car be compared to a gasoline car?

c. Use this real data to make a comparion of energy costs between a prius and a Matrix Prius: Requires 0.253 kwh/mile where each kwh costs ten cents Matrix: Requires 1 gallon of gas for every thirty miles, where each gallon costs two dollars

29


d. Rate the following energy sources in terms of cost, abundance and damage to the environmentâ&#x20AC;? Energy Source

Chemical (if any) involved

Cost (cheap, medium, expensive)

Abundance (running out, medium, plenty, renewable)

Damage to the environment (benign, medium, bad)

My opinion (excellent, okay, yuck) plus comments

Coal oil Natural gas Nuclear fission Nuclear Fusion tidal wave geothermal

E-85

biodiesel

solar

wind

8. Depending on your class, you may have learned some additional topics such as protein Kinase Mzeta and the ZIP molecule, the used and abused molecule tetrahydrocannabinol (THC), or details concerning nuclear fusion. Review your notes and have a good general knowledge of each topic.

8. Review the rest of your notes, worksheets, and lab experiments. Good Luck on the test.

30


31


Reaction Rates How can we find out how fast a chemical reaction goes? On July 20, 1944, a one-armed and one-eyed man broke a vial of acid and let the contents begin reacting with copper wire. In thirty minutes the wire would be severed, a massive chemical explosion would result, and Adolf Hitler would be assassinated. Colonel Claus Von Stauffenberg had just started an unstoppable chemical reaction that he believed would changed the course of history.

Colonel Claus Von Stauffenberg (left) as portrayed by Tom Cruise (right) in the Movie Valkyrie (2008).

that they would all be dead within minutes.

The rate of this chemical reaction had been carefully measured. Stauffenberg placed the bomb in a briefcase and calmly walked into the meeting room in the Wolfs Lair (Wolfschanze), where Hitler was in a meeting with the military leaders of the Third Reich. Inside the case, the acid was silently reacting with the copper wire.* A few minutes before the reaction of this fuse was complete Stauffenberg slipped out, confident

Stauffenberg should have stayed in the room. Moments before the wire was severed, the case was casually moved by one of the men, placing it right behind a large oak leg of the desk. At 12:40 P.M. the bomb detonated, and 975 grams of plastic explosive exploded with a massive force, killing many of the people in the room. Because of the last-minute shifting of the case, Hitler was injured but not seriously, and survived until April 30, 1945, when he took his own life. Before he did, Claus Von Stauffenberg was arrested, tortured, and executed. His final words were â&#x20AC;&#x153;Long live our sacred Germany!â&#x20AC;? In this unit we will be investigating the rate of chemical reactions, similar to the reaction used as a fuse to detonate the bomb in the attempted assassination just described. Our goal is to determine how these rates can be measured, and to study the energetics of these reactions. The most important skill to be learned in this unit is to be able to perform a chemical reaction and report how fast the reaction is going. To do this you will observe and perform several reactions and determine the reaction rates in various units. You will be able to quantitatively find out: -How fast does nitric acid react with copper wire (this was the fuse for the bomb described above) -How fast does magnesium react with hydrochloric acid? -How fast do things such as methanol, ethanol, and gasoline burn? *If time allows your instructor may demonstrate this chemical reaction using various inorganic acids and metal wires.

1


2


5 ways to change the rate of reaction • Hit it with a STICC! • Change the • 1. Surface area • 2. Temperature • 3. Identity (of reactants) • 4. Concentration (of reactants) • 5. Catalyst 4

3


4


5


Labs and Worksheets

6


Name: ______________________________________ Period: _____

lab13.1

Factors Affecting Reaction Rates Introduction: Chemical reactions occur at different rates. The combustion of methane is a relatively fast reaction, while the rusting of iron is quite slow. In general we would like to make the rusting of iron proceed as slowly as possible. On the other hand, an explosives chemical company might want to speed up the reactions that produce the explosives they sell. In order to understand how the rates of chemical reaction can be controlled, it is necessary to understand the collision theory of chemical reactions. A chemical reaction involves bond breaking and bond forming. The collision theory states that, in order to react, molecules must collide with each other with sufficient force and the correct positioning to break old bonds and form new ones. The minimum energy that the colliding molecules must have for the reaction to occur is called the activation energy. According to the collision theory, any factor that increases the number of molecular collisions that occur, or that increases the amount of energy with which the molecules collide, will increase the rate of the reaction. In this experiment, you will study the effect of temperature, concentration of reactants, particle size and surface area on the rates of chemical reactions. You will also investigate the effect that catalysts have on reaction rates. Catalysts are substances that provide a path of lower activation energy for reactions without being consumed. Objective: To observe the effects of temperature, concentration, particle size, surface area and catalysts on the rates of chemical reactions. Pre-lab questions: 1. Predict the effect of temperature, concentration, and particle size on the rate of a reaction.

3. An enzyme is an example of a catalyst: a substance that increases the rate of a chemical reaction without being consumed. Based on the collision theory, draw a picture of a how an enzyme might work.

7


Station One: The effect of temperature on reaction rate. 1. You have available magnesium, 6M HCl, ice water, and hot water. In one sentence describe your experiment. 2. Make a table of your data and carefully graph your results.

3. Write a balanced chemical equation for the reaction between hydrochloric acid and Magnesium. (Hint: It is a single replacement reaction, and Mg forms a +2 cation

4. Describe in your own words the effect of temperature on the rate of a reaction.

5. Explain this effect in terms of the collision theory.

Station Two: The effect of reactant concentration on reaction rate. 6. You have available magnesium, and HCl of various concentrations. In one sentence describe your experiment.

7. Make a table of your data and carefully graph your results.

8. Describe in your own words the effect of concentration on the rate of a reaction.

9. Explain this effect in terms of the collision theory.

8


Station Three: The effect of surface area on reaction rate. 10. You have available several metals of various shapes and sizes, a mortar and pestle, a pair of scissors, and hot plate capable of magnetic stirring. Note that stirring a solution will effectively increase the surface area of the reactants. In one sentence describe your experiment. 11. Tabulate your data and graph your results:

12. Write a balanced chemical equation for the reaction between hydrochloric acid and aluminum. (Hint: It is a single replacement reaction, and Al forms a +3 cation

13. Describe in your own words the effect of surface area on the rate of a reaction.

14. Explain this effect in terms of the collision theory.

Station Four: The effect of a catalyst on reaction rate. You have available a computer with access to the internet. Provide examples of three chemical reactions whose rate of reaction may be increased by the use of a catalyst. Do not attach any printouts. 15. Inorganic chemical reaction Write a balanced chemical equation: Catalyst(s): 16. Organic chemical reaction Write a balanced chemical equation: Catalyst(s): 17. Biological chemical reaction Describe this reaction, or write a balanced chemical equation: Catalyst(s): 18. Describe in your own words the effect of a catalyst on the rate of a reaction.

19. Explain this effect in terms of the collision theory. 9


Conclusions: 20. Of the various methods for increasing the rate of reaction, which do you believe can have the greatest effect and why?

21. You may have observed non-linear graphs. Explain this observation.

10


11


Name_____________________________Period________________________

Lab 13.2

Plastic Milk: A Reaction rate investigation Introduction: Milk is Arrhenius base, meaning that it has a pH >7 due to hydroxide (OH -) ions. When reacted with the mild acid in vinegar (acetic acid), The milk separates into curds, whey and casein. The casein is a polymeric protein (plastic) that separates to the bottom. Your tasks: 1. Develop a procedure that will create this plastic as rapidly as can be safely done. This may involve some trial and error. It may be useful to recall the 5 parameters that can increase the rate of a reaction: 1.________________. 2.________________. 3.________________. 4.________________. 5.________________. 2. Once your final procedure is developed, write an experimental procedure. Remember, a usable written procedure is one that can be repeated by anyone. 3. Once your plastic is isolated, you may mold it into any tasteful object you like. The following materials are available; you donâ&#x20AC;&#x2122;t have to use them all. Skim milk 1% milk Regular milk Red vinegar White vinegar Food coloring (for fun) 1M HCl Cloth and elastics for filtering Suggested procedure: Try mixing about 100 mL of milk with 10 mL of vinegar for starters. 1. Here is our original planned procedure. Be sure it is repeatable

2. To improve the speed of making this polymer, optimize 2 variables. Variable tested: Result 1. 2.

12


3. Based on this, here is our detailed final listed procedure.

4. Questions: A. Of the parameters you tested, which made the biggest difference and why?

During this investigation, have someone go online to answer: B. What is casein?

C. Write below the chemical structure of casein.

13


14


Name: ______________________________________ Period: _____

ws13.1

Reaction Rates Directions: For each of the following questions use the appropriate relationship or equation to solve the problem.

1.

2.

3.

15


4. Given the following data for the decomposition of hydrogen peroxide (H 2O2), calculate the rate of reaction in moles H2O2 consumed per liter per minute for each time interval. Initial concentration of H2O2: 3M Concentration of H2O2 after 3 minutes: 1.3M

5.

6.

16


Name: ______________________________________

Period: _____

ws13.2

Reaction Rates Practice Quiz Work in pairs and see how well you do on this practice quiz. Directions: For each of the following questions use the appropriate relationship or equation to solve the problem. 1. In the reaction of hydrogen and oxygen to create water, the concentration of hydrogen changes from 2 M at time = 0 to 0.2 M at time = 2 seconds. What is the reaction rate for this consumption of hydrogen?

2. List three ways to increase the rate of a chemical reaction.

3. Given the following data for the decomposition of hydrogen peroxide (H2O2), calculate the rate of reaction in moles H2O2 consumed per liter per minute for each time interval. Initial concentration of H2O2: 2.6 M Concentration of H2O2 after 3 minutes: 1.53 M

17


Questions 4-5 refer to the energy diagram above 4. For the energy diagram above, what single element is being transferred in the chemical reaction of carbon monoxide with nitrogen dioxide to form carbon dioxide and nitrogen monoxide?

5. Is the reaction above endothermic or exothermic?

Questions 6-9 refer to the energy diagram above 6. Which number refers to products? 7. Which number refers to activation energy?

18


8. Which number refers to the transition state, at which point the starting material and product form an activated complex?

9. Show the distance on the graph that represents the overall energy change for the reaction and indicate whether this reaction is endothermic or exothermic overall.

10. For the reaction: 2AlCl3 ď&#x192;  2Al + 3Cl2 The rate of loss of AlCl3 is 3 mol/L sec. Therefore the rate of formation of aluminum metal is also_______, and the rate of formation of Cl2 is ________.

Extra credit (1 point): Do the rates observed in question number 2 make sense, knowing that one mole of HCl reacts with one mole of Cl2 to form 2 moles of HCl? Explain.

19


20


How to Ace the Reaction Rates Test

howtoaceitunit13

In this unit we considered an important property of a chemical reaction: the rate at which it proceeds. We observed how concentration can affect the rate of a reaction, and came up with four other possible methods as well: temperature, surface area, the inherent reactivity of the reactants, and catalysts. All can greatly influence the rate of a reaction. We discussed ways to measure the rate of a reaction at any given point in time. This is easy enough, since the rate of a reaction is equal to the change in concentration over time. The concentration of the reactants will decrease, and products increase as a reaction proceeds. The units for concentration are mol/L, and bracketed chemicals indicate concentration; for example [HCl] literally means â&#x20AC;&#x153;the concentration of Hydrochloric Acidâ&#x20AC;?. We also looked briefly at the collision theory of a chemical reaction in order to understand the rate and energetics involved. Molecules must collide with enough force and at the right location on the molecule to form products. The moment where the new bonds are forming, and the old bonds are breaking is called the transition state, and that intermediate chemical is called the activated complex. This led to a discussion of the energy change in a chemical reaction, since forming the activated complex always involves adding energy to the system. That amount of energy is called the activation energy. Overall the reaction may be exothermic or endothermic, easily recognizable by comparing the energy state of the products compared to the reactants. These can easily be seen by looking at a reaction energy diagram. Once a reaction rate has been determined for a substance it is easy to find the rates for all other reactants involved, since it is proportional to the coefficients in the balanced reaction. In many cases chemists are not concerned what the rate of a reaction is, unless it is inconveniently slow or explosively fast. In our next unit we will see how the equilibrium of a reaction can prevent a lot of reaction from being isolated, and that usually bugs them. This topic (equilibrium) is coming up next.

To ace this unit you should review this entire packet, including lab experiments, powerpoint presentations, and worksheets. You should also be familiar with the information below: 1. Know the following terms: A. reactant B. product C. transition state D. activated complex 21


E. exothermic F. endothermic G. Activation energy Be able to determine 2. What is necessary for a chemical reaction to proceed (collision theory)

3. 5 ways to change the rate of a reaction

4. Given an energy diagram, be able to determine: How much energy a reaction, or the reverse reaction, needs to proceed 5. Where the transition state is 6.How exothermic or endothermic a reaction is

7. Rate of reaction given reaction time and concentration change • Example: • [HCl] at time = 0: 0.22 M • Start reaction • [HCl] after four seconds 0.32 M • What is the reaction rate? 8. In the energy unit we learned how to predict if a reaction will take place spontaneously. In this unit we determined how to measure how fast a reaction is. What is the relationship, if any, between reaction rate and spontaneity? To consider this, answer each question with a brief explanation - are fast reactions always spontaneous? - if the free energy of a reaction is highly positive, is it a slow reaction? -Are fast or spontaneous reactions dangerous -Are fast reactions exothermic? 22


23


The problem with chemical reactions is that the reverse reaction can, and usually does occur. To put it another way, for the reaction AB, while A is being converted to B, B is also being converted to A. This is equilibrium, a balance between forward and reverse reactions. In a sense, this means that a chemical reaction is never “done”, it simply gets to a point where the rate of the forward reaction is equal to the rate of the reverse reaction. Fortunately it is usually an easy matter to control this equilibrium. For example a reaction can be irreversibly driven to completion by removing the products as they are formed. Note that this doesn’t necessarily mean it will happen quickly: equilibrium and rate are two separate aspects of a chemical reaction.

In this unit we will learn how to calculate the concentrations of reactants and products at equilibrium, and we will use several methods to adjust the equilibrium in the direction we prefer.

Tentative Schedule: Lesson 1 Lab: Equilibrium Lab 1: Paper Clip Equilibrium Lesson: What is equilibrium? Writing and solving equilibrium concentrations. Homework: equilibrium worksheets 1 and 2 Lesson 2: Lab: Ester Lab reaction Lesson : Adjusting equilibrium: Le Chatelier’s Principle Homework : equilibrium worksheet 3 Lesson 3: Review In-class/homework: Equilibrium review worksheet 4; how to ace it guide Day 4: Equilibrium Test


Name: __________________________ Period: _____

equilibrium lab 1

Paper Clip Equilibrium Activity To demonstrate the characteristics of a reversible chemical reaction, imagine the reaction A + B  C below:

A

C

B

This is an example of a _______________ reaction. The reverse reaction is an example of a _________ reaction. At your instructors prompts, make as many C molecules as you can in 15 seconds. Then see how many you can take apart in 15 seconds. Record your answers in the box. Summary: C molecules made in 15 seconds (forward reaction): __________ C molecules decomposed in 15 seconds (reverse reaction): ________ At this rate, it would take ____ minutes for this reversible reaction to go to completion. 6. Before returning the materials to the front of the classroom, be certain the composition of the paper clips in the pile are the same as when your received them.

Summary Question: You have just simulated a reversible chemical reaction. In actual practice, the rate of a chemical reaction at constant temperature and pressure slows down over time until there is no change in the ratio of product to reactants. Explain this using collision theory.


What is it? How do I calculate it? How do I change it?

Chemical reactions are reversible forward

aA + bB

Chemical equilibrium:

= balance

Keq =

reverse

cC + dD

forward rate = reverse rate

[C]c[D]d

Omit liquids and solids

<1: mostly reactants (bad) >1: mostly products (good)

[A]a[B]b

1

What is it? How do I calculate it? How do I change it?

Write the equilibrium constant expressions:

H2(g) + I2(g) Keq =

FeO(s) + CO (g) Keq =

2HI (g) [HI]2 [H2][I2 ]

Fe(s) + CO2 (g) [CO2 ] [CO] 2


What is it? How do I calculate it? How do I change it?

2H2S(g) ? 2H2(g) + S2(g); Keq = 0.00227

If [S 2] = 0.0540 mol/L and [H2 S] = 0.184 mol/L, what is [H2]?

Keq = 0.00227 =

[H2S]2 [S2] [H2]

2

2

=

[H2] [0.054] [0.184]

2

[H2] = 0.0377 moles/liter 3

What is it? How do I calculate it? How do I change it?

Le Chatelierâ&#x20AC;&#x2122;s Principle Equilibrium can be adjusted by changing concentrations, temperature, or pressure. 4


What is it? How do I calculate it? How do I change it?

For A + 3B  C ∆H = +30 kcal/mole change

result

why

Add reactant



Add product

“quenching the fire”

Heat



Pressurize



It needs it (endothermic; ∆ H >0) Product has fewer moles (1 < 3)

“stoking the fire”

5

What is it? How do I calculate it? How do I change it? 2NO(g) + O 2(g) ? 2NO2(g)

∆H = +250 Kcal/mol

change 1. add [NO] 2. add [N O 2] 3. add [O 2] 4. remove [NO] 5. remove [NO 2 ] 6. remove [O 2] 7. Increase Pressure 8. Increase Temperature 9. Decrease Pressure 10. Decrease Temperature

shift       (3 to 2)  (endo)  

6


What is it? How do I calculate it? How do I change it?

The best way to drive a reaction to completion is:

â&#x20AC;˘ to remove the product as it is formed.

7


Name: _______________________

Period: _____

equilibrium lab 2

Perfume Lab Introduction: Esters may be prepared through the reaction of a carboxylic acid RCO2H with an Alcohol (R’OH), using a small amount of sulfuric acid as a catalyst.

RCO2H carboxylic acid

+

R’OH + alcohol

H2SO4



sulfuric acid

RCO2R’ ester

+

H2O water

+

H2SO4

sulfuric acid

Esters often have strong pleasant aromas. Carefully guarded mixtures of esters create expensive perfumes including Chanel #5, Aramis (for men) and others, some of which sell for hundreds of dollars per bottle. In this lab each student will create his own ester, and we will then share them to make perfumes.

For this chemical reaction, all of these reactants and products remain in solution. Therefore this reaction is reversible, and yields for this reaction can be low. In this experiment we will investigate the equilibrium mixture for this mixture after 24 hours.

Materials: Carboxylic acids listed on board Alcohols listed on board Sulfuric Acid (to be distributed by instructor) as a catalyst . Chemical Reaction Procedure: Mix 0.1 moles of your carboxylic acid, 0.1 moles of ethanol, and 5 drops of sulfuric acid. The calculations below will help make sure you are using the right amounts. Heat but do not boil on a hot plate for 20 minutes then store covered overnight.


Calculations: My carboxylic acid has a formula of _____, therefore one mole has a mass of ______g, and 0.1 mole has a mass of ______g. My alcohol has a formula of ______, therefore one mole has a mass of ______g, and 0.1 mole has a mass of ______g. Workup The following day, carefully neutralize the mixture with a measured amount of baking soda (NaHCO3). This reaction required ____g of baking soda for neutralization. Calculation: Sodium bicarbonate has a molecular formula of NaHCO3. Therefore one mole of NaHCO3 has a mass of ____g and 0.1 mole has a mass of ____g. Since ____ g of sodium bicarbonate reacted, this is ____moles of sodium bicarbonate. Therefore it reacted with ____moles of my carboxylic acid. Based on this we estimate that the reaction is ____% complete. All of the substances in the mixture are water soluble, except the fragrant ester you have produced. Bottle and artistically label the ester you have created. If time permits, combine small amounts of your perfume with those made by others to create your own perfume.

Results: 1. Based on our workup, our reaction created ___ g of ester after ____ hours for a ____ % yield. I would describe the odor of our ester produced as __________ I would describe the odor of our perfume as _______..

Questions

1. Show a balanced chemical equation for the reaction of acetic acid with baking soda.

3. Indicate three ways the yield of this reaction could be improved.


Name: _____________________________________

Date: ______

Science and Technology Posters 100 Points Introduction: Choose a poster on a topic of your choice. Topic: Each group of two will present a poster on any approved topic that is titled: The Chemistry of ____________________ Choose something that you are personally interested in. Possible topics include The Chemistry of : 1. A rose

19. Scopolamine

2. Explosives

20. Mouthwash

3. DNA

21. Life

4. The atom

22. Cellular phones

5. chocolate

23. Reverse osmosis

6. dirt

24. artificial blood

7. car tires

25. hydrofluoric acid

8. the space shuttle

26. chemical warfare

rocket engine

agents

9. A battery

27. organ transplants

10. Hybrid vehicles

28. the bliss molecule

11. nuclear power

29. pain

12. Nuclear warheads

30. anabolic steroids

13. The Connecticut

31. mucous

river

32. my fingernail

14. The ozone layer

33. really smelly gases

15. Liquid crystals

34. combinatorial

16. A basesball

chemistry

17. The sun

35. water

18. Coca-cola

Period: _____


Requirements 1. These posters are purely informational, not research based. The goal is to instruct the reader in a logical, succinct, and interesting way. No experiments or research is necessary. 2. These posters should reflect the fact that we are near to completion of a full year high school level chemistry course. Try to get as deep as you can into your subject. 3. There should be several chemical structures included in your poster, regardless of your topic. 4. There should be a properly cited reference section for your poster. Include trusted scientific sources wherever possible. 5. Include numerous images in your poster. Cite the source below the image if it is not original. There will be special prizes for the best poster from each group. Good luck to all.

10


Name: ____________________________________

Period: _____

equilibrium worksheet 1

Writing Equilibrium Concentrations Directions: Write the equilibrium constant expression for each of the equations illustrated below. These all follow the format: for aA + bB  cC +dD Keq = [C]c[D]d/[A]a[B]b 1. At 1405 K, hydrogen sulfide, also called rotten egg gas because of its bad odor, decomposes to form hydrogen and a diatomic sulfur molecule, S2. 2H2S(g) â&#x2020;&#x201D; 2H2(g) + S2(g) Write the equilibrium constant expression for this reversible reaction.

2. Methanol, a formula-1 race car fuel, can be made from carbon monoxide and hydrogen gas: CO(g) + 2H2 (g) â&#x2020;&#x201D; CH3OH(g) Write the equilibrium constant for this reversible reaction.

3. Write the balanced reaction for the combustion of hydrogen at 200 OC, and show that this is a reversible reaction.

Write the equilibrium constant for this reversible reaction.

4. Write a balanced reaction for the combustion of methane at room temperature. Be sure to include the physical states of the reactants and products.

Write the equilibrium constant for this reversible reaction.

11


Name: _______________________

Date: ______Period: _____ eauilibrium worksheet 2

Calculating Equilibrium Concentrations

Directions: Write the equilibrium constant expression for each of the equations illustrated below and solve for the missing value.

These all may be solved using the equilibrium constant expression: for aA + bB  cC +dD Keq = [C]c[D]d/[A]a[B]b

1. Lead sulfide may be prepared under high pressure by the reaction of lead with elemental sulfur: Pb(g) +S(g) â&#x2020;&#x201D; (PbS(g)

What is the value of the equilibrium constant (Keq) if [Pb] = 0.30 mol/L and [S] = 0.184 mol/L, and [PbS] is 2.00 mol/L?

How far has this reaction progressed? A. Unfortunately, it is still mostly reactants B. This reaction is mostly products

12


2. Methanol can be prepared from carbon monoxide and hydrogen: CO(g) + 2H2 (g) â&#x2020;&#x201D; CH3OH(g) Calculate these equilibrium constants: a. Keq when all substances have a concentration of 1 mol/L

b. Keq when all substances have a concentration of 2 mol/L

C. Keq when all substances have a concentration of 3 mol/L

d. For each reaction indicate if the reaction is mostly products, or mostly starting material.

13


Name: ____________________________ Period: _____

equilibrium worksheet 3

Le Chatelier’s Principle

"Placing a stress on an equilibrium causes the equilibrium to shift so as to relieve the stress" Or: Add reactant: reaction moves forward Add product: Reaction moves backward (reverse) Add temperature: Moves forward if endothermic (positive ∆H) Add pressure: moves toward the fewer number of moles. Remember, liquids and solids are considered to be outside of the reaction mixture – don’t count them when adding up moles. 1. For the following reaction ∆Ho = -1175 kJ

5 CO(g) + I2O5(s)  I2(g) + 5 CO2(g)

for each change listed, predict the equilibrium shift and the effect on the indicated quantity.

Change

Direction of Shift

Effect on Quantity

( → ; ← ; or no change)

(a) (b) (c) (d) (e)

decrease in volume raise temperature addition of I2O5(s) addition of CO2(g) removal of I2(g)

Effect (increase, decrease, or no change)

amount of CO (g) amount of CO(g) amount of CO(g) amount of I2O5(s) amount of CO2(g)

2. Consider the following equilibrium system in a closed container: Ni(s) + 4 CO(g) ↔ Ni(CO)4(g)

∆Ho = - 161 kJ

In which direction will the equilibrium shift in response to each change, and what will be the effect on the indicated quantity? Direction Effect on Effect (increase, decrease, Change of Shift Quantity or no change)

( → ; ← ; or no change)

(a) (b) (c) (d) (e) (f) (g)

add Ni(s) raise temperature add CO(g) remove Ni(CO)4(g) decrease in volume lower temperature remove CO(g)

Ni(CO)4(g) Kc amount of Ni(s) CO(g) Ni(CO)4(g) CO(g) Kc 14


Name__________________________ Period________

equilibrium worksheet 4

Equilibrium Review Worksheet

Note: Several of these questions may be omitted on your instructor’s discretion. 1)

What is the best way to drive a reversible reaction to completion?

2)

Write the gas equilibrium constant (Kc) for each of the following chemical reactions.

3)

a)

CS2(g)

+

H2 (g)

CH4 (g) +

b)

Ni

+

CO(g)

Ni(CO)4 (g)

c)

HgO(s) ⇔

Hg

(l)

+

O2(g)

d)

HCl (g)

+

O2(g)

H2O (l) +Cl2(g)

e)

HCl (g) +

O2(g)

H2O(g) +

f)

Ag+(aq)

+

Cl-(aq)

g)

CO2 (aq) +

H2O (l) ⇔

(s)

H2 (g)

Cl2(g)

AgCl (s)

HCO3- (aq)

+

H3O+(aq)

Which side of the equilibrium is favored, products or reactants, for each of the following

where, A

B.

a)

Keq = 1.375 x 10-3

b)

Keq = 1.375 x 10+3

c)

Keq = 1.00 x 100

5)

In your own words, paraphrase Le Chatelier's Principle.

6)

For the following equilibrium:

15


N2

(g)

+

H2(g)

NH3

(g)

∆H= -386 KJ/mole

Predict the direction the equilibrium will shift if:

7)

a)

N2 is added?

b)

H2 is removed?

c)

NH3 is added?

d)

NH3 is removed?

e)

the volume of the container is decreased?

f)

the pressure is increased by adding Argon gas?

g)

the reaction is cooled?

h)

equal number of moles of H2 and NH3 are added?

The equilibrium constant for the following reaction is 5.0 at 400 °C. CO

(g)

+

H2O(g)

CO2

+

(g)

H2

(g)

Determine the direction of the reaction if the following amount (in moles) of each compound is placed in a 1.0 L flask. CO

8)

(g)

H2O

(g)

CO2 (g)

H2

(g)

a

0.50

0.40

0.80

0.90

b

0.01

0.02

0.03

0.04

c

1.22

1.22

2.78

2.78

d

0.61

1.22

1.39

2.39

The equilibrium concentrations of [O2] = 0.21 Molar and [O3] = 6.0 x 10-8 Molar, calculate the

value of Kc. O3 (g) 9)

O2(g)

At a particular temperature a 2.0 L flask contains 2.0 mol H2S, 0.40 mol H2, and 0.80 mol S2.

Calculate Kc at this temperature for the reaction: H2 (g)

+

S2 (g) ⇔

H2S (g)

10) The following equilibrium pressures were observed for the reaction

16


N2 (g)

H2 (g)

+

NH3 (g)

PNH3 = 3.1 x 10-2 atm PN2 = 8.5 x 10-1 atm PH2 = 3.1 x 10-3 atm Calculate the value for the equilibrium constant Kp. 11) For the equilibrium: CH4 (g) ⇔

H2C2

(g) +

H2(g)

The initial concentration of CH4 is 0.0300 M and the equilibrium concentration of H2C2 is 0.01375 M: a) calculate the equilibrium concentrations of CH4 and H2; b) Determine the numerical value of Kc. 12) If the equilibrium partial pressures are PCO2 = 0.0387 atm and PNH3 = 0.0774 atm, what is the value of Keq for: H2NCO2NH4 (s)

NH3

(g)

+

CO2

(g)

13) For the equilibrium; H2 (g)

+

I2 (g)

HI

(g)

Kc = 54.5 at 425 °C.

If 0.020000 M HI (g) is allowed to reach equilibrium, predict the concentrations of H2(g), I2(g), and HI(g)? 14) The equilibrium constant, Kc, is 0.1764 at 1500 °C for : CO

(g)

+

H2 (g)

CH4 (g) +

H2O (g)

If the initial concentration of CO is 0.1000 M and the initial concentration of H2(g) is 0.300 M, what are the equilibrium concentrations of all species? 15) For the equilibrium at a certain temperature: COCl2

(g)

CO (g)

+

Cl2 (g)

Kp = 6.7 x 10-9. Starting with pure COCl2 (g) at a pressure of 1 atm. Calculate the partial pressures of each of the three gases. 16) At a particular temperature, 8.0 mol NO2 is placed into a 1.0 L container and the NO2 dissociates by the reaction: NO2(g) ⇔

NO

(g)

+

O2(g)

At equilibrium, the concentration of NO is 2.0 M. Calculate Kc for this reaction. 17) At a certain temperature, 4.0 mol NH3 is introduced into a 2.0 L container, and the NH3 partially dissociates by the reaction:

17


NH3

(g)

N2

(g)

+

H2(g)

At equilibrium, 2.0 mol NH3 remains. What is the value of Kc for this reaction? 18) At a particular temperature, K = 2.50 for the reaction: SO2

(g)

+

NO2

(g)

SO3(g) +

NO(g)

If all four gases had the initial concentration of 1.00 M, calculate the equilibrium concentrations of the gases. 19) At a particular temperature, Kc = 1.00 x 102 for the reaction: H2(g) a)

+

F2

(g)

HF (g)

In an experiment, 2.00 mol H2 and 2.00 mol F2 are introduced into a 1.00-L flask.

Calculate the concentration of all species at equilibrium. b)

To the equilibrium mixture from part a, an additional 0.50 mol H2 is added. Calculate

the new equilibrium concentrations of all gases. 20) At some temperature, Kp = 0.050 for the reaction N2

(g)

+

O2

(g)

NO(g)

In an experiment, 0.2 mol of O2 and 0.8 mol of N2 were introduced into a flask at a total pressure of 1 atm. Calculate the partial pressure of NO at equilibrium. 21) Write the solubility product for the dissolution of : a)

Calcium fluoride

b)

Magnesium nitrate

c)

Aluminum phosphate

d)

Potassium bicarbonate

e)

Sodium sulphate

22) Calculate the solubility constant Ksp from the following information. a)

The solubility of potassium iodate, KIO3, is 43 g/L.

b)

The solubility of AgI is 9.1 x 10-9 M.

23) The solubility constant Ksp for Barium Sulphate is 8.7 x 10-11. a)

Calculate the solubility of Barium Sulphate in water. b)

Calculate the solubility of barium sulphate in 0.15 M Sodium Sulphate solution.

18


Howtoaceitunit18 How to Ace the Equilibrium Exam

In our previous unit we investigated the rate of chemical reactions- how fast do they go? In this equilibrium unit we point out that even if a reaction is going fast, it might not be going very far overall if the reverse reaction is also occurring. This is the big idea behind chemical equilibrium, the condition where the rate of a forward reaction is equal to the rate of the reverse reaction.

We can write the equilibrium constant expression and from this we can determine if we are getting anywhere or whether the reaction is standing still. Generally speaking, if one mixes chemicals together they would like them to go forward, and this will happen if the value of the equilibrium constant (Keq) is greater than one. Note that Keq is only true at a specific temperature, and it says nothing about the rate of a reaction- only the direction.

A nice benefit of the equilibrium constant expression is that it can also tell you what the concentration of a reactant is, given enough information.

Since chemical equilibrium can prevent a reaction from going to completion, it would be nice to know how we can destroy it, or at least get things moving forward. Simple. To destroy chemical equilibrium, one can remove the product as it is formed- this makes the reverse reaction impossible. This is usually accomplished by having the product crash out of solution, for example by precipitating as a solid.

For this reason those chemicals which precipitate from a chemical reaction are omitted from the equilibrium expression.

There are several other ways one can adjust chemical equilibrium. Known as Le Chatelierâ&#x20AC;&#x2122;s Principle, the direction of a reaction after a stress is applied may be summarized:

Adding reactant:  Adding product: 

19


Heating:  if endothermic Pressurizing:  if there are fewer moles of product

Each of these may be reversed; for example cooling an endothermic reaction will favor the reverse reaction.

Imagine going on a trip. Itâ&#x20AC;&#x2122;s nice to know in what direction you are going, and how long it will take. These last two units have shown us just that for a chemical reaction. In the next unit we can apply these navigational skills to the study of acids and bases.

To ace this exam you should know:

1. What is chemical equilibrium?

2. What is a synonym for equilibrium?

3. What is the best way to destroy chemical equilibrium?

4. What does it mean if the rate of a forward chemical reaction a. Is faster than the reverse reaction

b. Is the same as the reverse reaction?

c. Is slower than the reverse reaction?

5. Please balance the reaction below and write the chemical equilibrium expression:

Fe3O4(s) + 4H2(g)  3Fe(s) + 4 H2O (g)

20


Keq =

6. Please determine the direction of the reaction given the following data:

C2H4(g)

+

H2 (g) 

a. 1M

2M

b. 1.0520M

C2H6(g)

H = +32kJ/mol

3M

3.0400M

Direction of reaction:______

3.1909M Direction of reaction:______

7. For the reaction below the rate of the forward reaction is equal to the rate of the reverse reaction. Therefore, Keq = ____. Determine the concentration of ethane (C2H6) in the mixture:

C2H4(g) + H2 (g)  C2H6(g) 2M

4M

H = +32kJ/mol

?

8. Please determine the direction of the following hypothetical reversible reaction: 4A(g) + 7B(g) + 13C +D (l)  9E (g) + 3F (g)+ 2G (g) Concentrations (M):

1.06

2.12

1.42

3

2.10

1.44

3.26

9. Please determine the concentration of G in the following reaction if it is at equilibrium.

21


4A(g) + 7B(g) + 13C +D (l)  9E (g) + 3F (g)+ 2G (g) Concentrations (M):

1.06

2.12

1.42

3

2.10

1.44

?

9. List five ways to help the following reaction move forward: C2H4(g) + H2 (g)  C2H6(g) â&#x2C6;&#x2020;H = +32kJ/mol

1. 2. 3. 4. 5.

22


23


Chapter 15 How do we explain, measure, and neutralize acids and bases?

Acids and Bases

Strong acids and bases are often powerful, dangerous substances. Sulfuric acid (H2SO4) will decompose sugar into black charcoal. Nitric acid (HNO3) reacts with many metals, and hydrochloric acid (HCl) will eat away at a penny from the inside out. The base sodium hydroxide (NaOH) will react with grease and even human hair, and hydrofluoric acid (HF) cannot be stored in bottles since it reacts with glass.

What makes these substances so reactive? What is the essential chemical unit of an acid or a base? We can find the answers to these questions by taking a close look at the most abundant chemical on earth, which also the most abundant chemical in our bodies:

Water.

What is water? If you took a liter of absolutely pure water, you would find not one substance, but three. (Actually you would find more than that if you include isotopes, but that is another story). The major substance is H2O which we are all familiar with, and the other two are the essential chemical forms of acid and bases. These three exist in chemical equilibrium, which we just studied.

In this unit we will take a close look at this equilibrium and how we can conveniently measure it: this is pH. We will perform a simple chemical assay to measure the exact acid or base composition of any aqueous substance: titration. Finally, we will find out what gives these substances such potent chemical reactivity.

1


Schedule As we have done for each unit, you will begin with a discovery lab, the goal of which is to explore the properties of the acidic and basic substances that you encounter every day. We then will hear from the experts, and take a look at the conclusions they have drawn. By the end of this unit you will be able to 1. Recognize common acids and bases 2. Measure the acidity and basicity of any substance using several different methods 3. Understand what an acid or base is using 2 complementary definitions 4. Determine how pH is related to acid or base concentration (L1 only) 5. Precisely measure the acidity or basicity of any substance by titration. Lesson Lesson Lesson Lesson Lesson Lesson Lesson

1: Household acids and bases lab 2: What is water? pH and exponents 3: More acid/base math 4: Neutralization 5: Neutralization Lab 6 Review 7: Acid/base test

2


3


4


5


6


7


8


Name: _______________________________ Period: _____

Acids and Bases Lab 1

Household Acids and Bases Introduction: Many common household solutions contain acids and bases. Acid-base indicators such as litmus paper or even red cabbage juice turn different colors in acidic and basic solutions. They can, therefore, be used to show if a solution is acidic or basic. An acid turns blue litmus paper red, and a base turns red litmus paper blue (remember Blue = Basic). The acidity of a solution can be expressed using the pH scale. Acidic solutions have pH values less than 7, basic solutions have pH values greater than 7, and neutral solutions have a pH value equal to 7. In this experiment, you will test the pH of various household substances using a pH meter, variable-range pH paper, litmus paper, and a selection of juices. Our goal is to evaluate the accuracy and precision of each technique. Procedure: Obtain a few drops of each solution and evaluate the acidity or basicity of each substance using the techniques indicated. Watch carefully as your instructor demonstrates the method to use for each assay. Data Table: Test Tube

Solution

Blue Red Litmus Litmus paper paper

pH Paper

Red Cabbage Juice:

(1-14)

(draw color)

pH meter (0.014.0)

1

cherry Juice:

Phenolphthalein

(draw color)

(draw color)

Distilled Water

2 3 4 5 6 7 8 9

9


Conclusions/Questions: 1. Which of the household solutions tested are acids?

2. How can you tell?

3. Order the acids by increasing pH.

Lowest pH (most acidic

Highest pH (most basic)

2. Which of the solutions are bases? How can you tell? Order the bases by increasing pH.

3. Using a crayon or markers, draw a color guide for measuring the ph of a substance using your juice indicators: Indicator juice 1: red cabbage juice 0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

5

6

7

8

9

10

11

12

13

14

6

7

8

9

10

11

12

13

14

Indicator juice 2: cherry juice 0

1

2

3

4

Indicator juice 3: phenolphthalein 0

1

2

3

4

5

4. Can each juice indicator be used to determine the strength of acids and bases? Explain.

5. Which test method is superior overall? Why?

10


Name_________________________ Date_________ Period________

acids and bases lab 2

Percentage of acetic acid in vinegar by titration Introduction Vinegar is a mixture of acetic acid (C2H4O2) and water. Is it mostly water, or mostly acetic acid? In this experiment we will find the percent acetic acid in vinegar by mass. Since acetic acid is an acid, it will react with a base. The more base it takes to neutralize the acetic acid, the higher the concentration of acetic acid. This principle is known as titration: Assaying the concentration of an acid or base by neutralizing it. Procedure 1. Fill a buret with 1M NaOH and record the initial volume:____ 2. Add exactly 25 mL of vinegar and 3 drops of phenolphthalein to a flask and place it under the buret. 3. Drip in the 1M NaOH while stirring until the solution just becomes permanently pink. Record the final volume:_____ Total NaOH added: _____ mL (trial 1) 4. Perform a second trial Total NaOH added: ____ mL (trial 2) Average volume NaOH added:______________ mL 5. Calculate the Molarity of the vinegar using the titration formula:

Molarity of unknown =

molarity of known x liters of known liters of unknown

(This equation is true only when the known and unknown react on a equimolar basis, which is true in this case) For this experiment we can rewrite the formula:

11


vinegar Molarity =

(NaOH Molarity)(NaOH volume) vinegar volume

The NaOH Molarity as well as the vinegar and NaOH volume can be found above in bold. Molarity of vinegar = _______ M

6. To calculate the percent acetic acid in the vinegar, we need to convert from grams to moles., where 60 grams of acetic acid (C2H4O2) is a mole. Here is a sample calculation starting from a 3 Molar acetic acid solution:

60 grams acetic acid 180 g acetic acid 3 moles acetic acid 1 liter solution x x = = 18% Liter solution 1 mole acetic acid 1000 grams solution 1000 g solution Rewrite this below using your calculated acetic acid Molarity from the bottom of the previous page, and show your cancelled units:

% CH3CO2H = _______ % Finally, we can calculate the pH of this solution, since this is the negative log of the vinegar Molarity. Here is a sample concentration based on a vinegar Molarity of 0.25 moles/liter: -log .25 = 0.6; this is a strong acid. Please return all equipment and clean your stations completely.

12


Name_____________________ Period____

acids and bases lab practical

Acids and Bases: Lab Practical ___ Points Each group will be given an unknown acid or base. Our sample number is __________ Find out 1. If it is an acid or a base 2. The pH of the solution 3. The Molarity of the solution. Results: 1. To determine if our solution is acidic or basic, we used the following procedure:

This showed that our solution is a(n) acid/base (circle one) 2. To determine the pH of the solution we performed the following test(s):

This showed that the pH of our solution is____________ (please give your answer with three significant figures) 3. To determine the Molarity of the solution, we used the following procedure:

This showed that we were given a _____M solution (please give your answer with three significant figures). Final Results: We were given sample #_____, which is a(n) acid/base (circle one) with a pH of _____ and it is a ______M solution.

13


14


Name

Period

ws15.1

Acids & Bases

Water is amphoteric, which means it has both the components or an Arrhenius acid (H+) and an Arrhenius base (OH-). However, an aqueous solution of ammonia (NH3) has a pH of 13 and is definitely a base, but it doesn‟t contain the hydroxide anion. Instead, it creates then hydroxide anion when it reacts with water; here is the ionization reaction: NH3 + H2O  NH4+ + OHThis reaction has produced ammonium hydroxide (NH4OH); by showing the ions separately we can see what has happened. Ammonia has accepted a proton (H+). Ammonia is an example of a Bronsted-Lowry base: a substance that accepts a proton. A Bronsted-Lowry acid is a substance that donates a proton. Look at the equilibrium reaction again. When bases accept protons they form conjugate acids: NH4+ is an example of a conjugate acid. When acids lose protons they form conjugate bases: OHis an example of a conjugate base.

1. Summarize the two main acid-base theories in the table below. ACID

BASE

Arrhenius

Brønsted-Lowry

2. What is a conjugate base? 3. What is a conjugate acid?

15


Label the acid (A), base (B), conjugate acid (CA), and conjugate base (CB) in each of the following reactions. Example:

HCl

+

H 2O

Acid

base

H3O+ conj. acid

+

Clconj. base

4. H2SO4 + NH3  HSO4- + NH4+ ____

___

___

___

5. CH3CO2H + H2O  H3O+ + CH3CO2____

___

___

___

6. CH3NH2 + H2O  CH3NH3+ + OH____

___

___

___

Give the conjugate base for each of the following Brønsted-Lowry acids. Examples: HSO4- SO42- (to form a conjugate base remove H+) HBr Br7. HI _______ 8. NH4+ ________ 9. H2CO3 _________ d. HNO3 ________ Give the conjugate acid for each of the following Brønsted-Lowry bases Example: H2O: H3O+ (add H+ to form a conjugate acid) 10. OH-

____________________

11. O2– 12. CH3CO2– ________________ 13. NH3 _______________________

16


Ws15.2 Name: ________________________ Period: ____

Chemistry: pH and pOH calculations

Date:

___________

pH + pOH = 14

Part 1: Fill in the missing information in the table below. Example: Given a pH of 1, an example would be battery acid, the pOH is 13, and the substance is an acid. pH

Example

pOH

3.7 vinegar 4.8 8.3 Cow’s milk 3.0 13.0 0.9

ACID or BASE?

pH of Common Items                         

1.0 battery acid 2.2 vinegar 2.4 lemon juice 2.6 Coca Cola 3.3 apple juice 3.4 fruit jellies 3.5 strawberries 3.7 orange juice 4.5 tomatoes 5.6 unpolluted rain 6.4 peas 6.4 butter 6.4 cow's milk 6.5 corn 7.0 maple syrup 7.0 distilled water 7.3 human blood 7.5 human saliva 8.0 egg whites 8.3 baking soda 9.2 borax 10.5 milk of magnesia 11.0 laundry ammonia 13.0 lye 13.1 Drano

17


Name ___________________________ Period ___

ws15.3

Aqueous Acids and Bases â&#x20AC;&#x201C; Additional Topics Please know the names, formulas, and common names of the following common acids and bases: Common name Name Formula Acid or base? lye Sodium hydroxide NaOH potash Potassium hydroxide KOH fuming Sulfuric acid Oleum H2SO4 vinegar Acetic acid CH3CO2H ammonia (Ammonia) NH3 stomach acid Hydrochloric acid HCl Acid rain Nitric acid HNO3 lime Calcium hydroxide Ca(OH)2 Milk of magnesia Magnesium hydroxide Mg(OH)2 Also, be aware that there is a difference between a strong acid or base, and a concentrated acid or base. A strong acid or base ionizes completely in solution. These include for example hydrochloric acid, nitric acid, and sulfuric acid (H2SO4). Weak acids and bases such as acetic acid or citric acid hold on to their acidic proton more tightly- they only ionize partially in solution. If acids or bases they are diluted with a lot of water, however, they become dilute. As an arbitrary rule, we will consider any solution of an acid or base with a concentration greater than 1M to be a concentrated acid. Read this information carefully, then answer the questions below.

1. What is this stuff? Write the chemical formula for each

NaOH

______ __________

________

_______

2. Write the formulas for Sulfuric acid: H2SO4 Nitric acid:___________ Acetic acid:________ Magnesium hydroxide:_________ 18


3. Write the name for Ca(OH)2 HBr 4. Write the chemical reaction between water and hydrofluoric acid, and identify each substance as an acid, base, conjugate acid, and conjugate base. Circle the hydronium ion (H3O+).

5. The equilibrium constant for this reaction (surprisingly) is 6.3 x 10-4. What does that tell you about hydrofluoric acid? 6. A 14M solution of HF would be an example of a a. concentrated dilute acid b. concentrated weak base c. Concentrated weak acid d. Dilute strong acid 7. What is the difference between an Arrhenius base and a Bronsted-Lowry Base?

8. Give an example of a dilute strong acid:

9. Write the chemical equation for the reaction between hydrochloric acid and water: a. Identify the acid, base, conjugate acid, and conjugate base b. Circle the hydronium ion c. Is the water acting as an Arrhenius base of Bronsted-Lowry base? d. Write the formula for Ka (this is the same as Keq) for this reaction. e. Predict the value of Ka for this equilibrium.

19


Name______________________________

Period________

ws15.4

Chemistry: pH and pOH calculations We are mostly water. So is our planet. Most of our chemistry experiments use water. Thus, we should know what water is in detail. It‟s H2O, right? Not quite. About one in every million molecules of water is ionic, existing as H+OH-, not the polar covalently bonded H-O-H. When we add bases like NaOH to water, the water has more OH- in it, and when we add acids like HCl the water has more H+ in it. A liter of pure water has 10-7 moles of H+ in it, and 10-7 moles of OH- in it. That‟s 0.0000001 moles. A liter of battery acid, on the other hand, has 10-1 moles of H+, and 10-13 moles of OH- in it. That‟s 0.1 moles, which is a million times as many moles of H+, and a million times fewer OH- moles. Someone came up with the bright idea of using the exponents, and “10-7 moles per liter hydrogen ion concentration” became simply known as pH 7, where pH means “powers of hydrogen” Since the log of 10-7 is -7, we are taking the negative log when we convert from concentration to pH: pH = -log [H+]. Note also that the more acidic something is, the less basic it is. In our example above, battery acid has a hydrogen ion concentration of 10-1 moles per liter, or a pH of 1: Battery acid (H2SO4): [H+] = 10-1M = pH 1 It also has a hydroxide ion concentration [OH-] of 10-13M, which is a pOH (“powers of hydroxide”) of 13: Battery acid (H2SO4): [OH-] = 10-13M = pH 13 The pH and the the pOH always add up to 14. This means that the H+ and OH- concentrations always can be multiplied to equal 10-14M pH + pOH = 14 [H+][OH-] = 10-14 We can summarize the relationship between concentration and pH:

pH + pOH = 14

[H+] = 10-pH

pH = -log [H+]

[H+][OH-] = 10-14

[OH-] = 10-pOH

pOH = -log [OH-]

Making sense of this for the first time can take time. The examples on the next page will enable you to master these concepts.

20


Use the details provided below for the first row to help fill in the table.

[H+][OH-] = 10-14 Enter 10^-14/1.66E-4

pH 3.78 [H+] = 10-pH

Enter 10^-3.78

[H+]

pOH

[OH-]

Acid or base? Example

1.66 x 10-4

10.22

6.0 x 10-11

Acid Orange juice

pH>7 = base pH<7 = acid

pH + pOH = 14 Enter 14-3.78

Use the change sign (-) button, not the subtract button

Part 1: Fill in the missing information in the table below.

pH 1.

[H+]

pOH

3.89 x 10–4 M

3.

5.19

4.

4.88 x 10–6 M 8.46

6.

8.45 x 10–13 M

7.

2.14

8. 9. 10. 11. 12.

ACID or BASE? Example

3.78

2.

5.

[ OH– ]

2.31 x 10–11 M 10.91 7.49 x 10–6 M 9.94 2.57 x 10-8 21


Part 2: For each of the problems below, assume 100% dissociation. 1.

2.

A.

Write the equation for the dissociation of hydrochloric acid.

B.

Find the pH of a 0.00476 M hydrochloric acid solution.

A.

Write the equation for the dissociation of sulfuric acid.

B. Find the pH of a solution that contains 3.25 g of H2SO4 dissolved in 2.75 liters of solution.

3.

4.

5.

A.

Write the equation for the dissociation of sodium hydroxide.

B.

Find the pH of a 0.000841 M solution of sodium hydroxide.

A.

Write the equation for the dissociation of aluminum hydroxide.

B.

If the pH is 9.85, what is the concentration of the aluminum hydroxide solution?

A.

Write the equation for the dissociation of calcium hydroxide.

B.

If the pH is 11.64 and you have 2.55 L of solution, how many grams of calcium hydroxide are in the solution? 22


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Name: ___________________________________ Period: _____

ws15.5

Titrations Directions: Answer each of the questions below with the correct reaction, volume or molarity for either the acid or base in question. Use the solved examples as a guide. Fill in the missing products or reactants: Example: CsOH + HBr 

CsBr + H2O

1. HCl + _______  KCl + H2O 2. 2HF + Mg(OH)2  _________ + ___________ 3. NH3 + HNO3 

_____________

Example: What is the molarity of a CsOH solution if 30.0 mL of the solution is neutralized by 26.4 mL of 0.250 M HBr solution?

solution : molarityCsOH =

(molarityHBr )(volumeHBr ) volumeCsOH

=

(0.250M)(26.4 mL) = 0.22M Solution: (30.0 mL)

2. What is the molarity of a HCl solution if 43.33 mL 0.100 M KOH solution is needed to neutralize 20.00 mL of unknown solution?

3. What is the concentration of a household ammonia cleaning solution if 49.90 mL of 0.5900M HCl is required to neutralize 25.00 mL of the ammonia solution?

4. In a titration, 33.21 mL 0.3040 M Rubidium Hydroxide solution is required to neutralize 20.00 mL HF solution. What is the molarity of the Hydrofluoric Acid solution?

5. A 35.00 mL sample of NaOH solution is titrated to an endpoint by 14.76 mL 0.4122 M HBr solution. What is the molarity of the NaOH solution? 24


25


Name ________________________________ Period ___

ws15.6

Titration: challenge problems 1. 49 mL of 0.200 M HCl is mixed with 50 mL of 0.200 M NaOH to reach the endpoint. a. moles HCl = b. moles NaOH = c. [H+] d. [OH-] e. pOH = f. pH = 2. 86.30 mL of an HCl solution was required to neutralize 31.75 mL of 0.150 M NaOH. Determine the molarity of the HCl.

3. 63.15 mL of calcium hydroxide is required to titrate 18.9 mL of a 0.200 M H 3PO4 solution. What is the molarity of the basic solution?

4. How many mL of 0.160 M HClO4 are needed to titrate 35.0 mL of 0.215 M LiOH?

5. 25.0 mL of 1.00 M HCl are required to titrate a Drano solution (active ingredient NaOH). How many moles of NaOH are present in the solution?

6. Ten grams of vinegar (dilute acetic acid, HC2H3O2), is titrated with 65.40 mL of 0.150 M NaOH. a. What is the Molarity of the vinegar solution? b. How many grams of acetic acid are present in a one liter of the vinegar solution? c. How many grams of acetic acid are present in 10 grams of the vinegar solution d. How many molecules of acetic acid are present in 10 grams of the vinegar solution?

26


27


Name: ______________________________________

Period: _____

WS15.7

The Secrets behind the “Water into Wine” Demonstration Worksheet We recently saw the water into wine demonstration, where Water (colorless)  Wine (pink)  Martini (colorless) champagne (fizzy)  milk (cloudy)  margarita (opaque pink) To do this we hid small amounts of colorless chemicals in the original water decanter, as well as the individual glasses: 1. Water: The water contained a few drops of phenolphthalein, a colorless liquid acid, which we can draw as Phenolphthalein-H where H is the acidic proton that it will donate, as all acids do (recall the Bronsted-Lowy definintion of an acid). So the water glass (which doesn‟t contain anything) is colorless. 2. Wine: The wine glass has a few drops of dilute NaOH in it: a strong base. Write the resulting acid-base reaction (Hint: it is a double replacement reaction, and acids donate protons): Phenolphthalein-H + NaOH  __________________+________________ The sodium salt of phenolphthalein (which you just drew above) is a vivid pink substance- hence the rose wine. Thus phenolphthalein solutions are colorless in acidic pH, and pink when basic. This makes them useful as indicators, much like pH paper. 3. Martini: A martini is colorless. How can we make our pink phenolphthalein solution colorless? (Hint: reacting it with base made it pink). Answer:___________________________________ For this we use sulfuric acid. Write out the products for this double replacement reaction: (Hint: remember what acids do). Phenolphthalein-Na+ + H2SO4  _______ + ____________ We are back to normal phenolphthalein, a colorless martini-looking liquid. 4. Champagne: Since we are back to an acidic solution (we used excess sulfuric acid), we can generate some fizz by reacting it with baking soda. Please fill in the intermediate and final products: H2SO4 + NaHCO3  _________ + _________  CO2(g) + _____________ 28


5. Milk: Our milk glass contains some barium nitrate. Balance and write the products for this double replacement reaction (hint: SO4 is a 2- anion, NO3 is a 1- anion): ____Na2SO4 + ____BaNO3  ______________ + _____________ At least one of these products is insoluble in water- the precipitate makes the solution look „milky”. 6. Strawberry Margarita: Finally, we hide excess strong base in the margarita glass. We‟ve got all kinds of stuff in there now, but colorwise the phenolphthalein will dominate. Write out the reaction again between phenolphthalein and sodium hydroxide to form our hot pink and this time still opaque solution: _______________ + ________________  ______________ + ____________ And that‟s the science behind the magic.

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Name____________________ Period_________

how to ace the acids and bases test

How to ace the acid-base test In this unit we explored the properties of acids and bases. We started by getting a feel for acids and bases by checking the pH of a number of household chemicals. We found that bases tend to be slippery, and acids tend to be sour or bitter. We explained this by exploring two models: The

Arrhenius model and the Bronsted-Lowry model. We then applied this model to acids and bases, and identified a dozen compounds that serve as examples of each.

We then looked at these substances quantitatively by examining the pH scale of acids and bases. We observed that the ion concentrations in water are quite low, and that the equilibrium constant Kw of water is 1 x 10-14 moles per liter.

Finally, we all learned a technique for precisely measuring the pH of any solution: titration.

The molecular basis of aqueous acidity involves the movement of the hydrogen cation (H +). In the next chapter we will follow the movement of electrons between molecules, and this will serve as the basis for understanding chemical reduction and oxidation.

To ace the acids and bases exam review all labs, worksheets, slides and notes. And pay particular attention to the guided questions on the following pages.

Please remember to bring your calculator to this exam.

30


1. Know your â&#x20AC;&#x17E;vocabâ&#x20AC;&#x;; remember for this exam you are required to know the names and formulas of the following common acids and bases: Hydrochloric acid

Hydrobromic acid

Nitric acid

Hydrofluoric acid

Sulfuric acid

Acetic acid

Sodium hydroxide

Potassium hydroxide

Magnesium hydroxide

Calcium hydroxide

Sodium bicarbonate

Ammonia

2. Know the meaning of the following terms: a. Arrhenius acid b. Arrhenius base c. Bronsted-Lowry acid d. Bronsted-Lowry base e. titration f. Strong acid g. Strong base h. pH i. Acid pH j. Base pH k. Neutral pH l. Conjugate acid m. Conjugate base. m. Neutralization reaction n. Concentrated acid or base

o. dilute acid or base p. 2 weak acids

q. 1 weak base

31


3. Know how to use your formulas (They will be provided on the exam; be able to know how to use them) Kw = [H+][OH-] = 10-14 pH + pOH = 14 titration: [unknown] = (volume

kwnn)(molarity known)/(volume unknown)

Example: For pH 3 solution [H+] = _____, [OH-] = _____, pOH =____, the solution is Acidic/basic.

3. Be able to solve the problems on the worksheets: a. acids and bases worksheet -Be able to label the acid, base, conjugate acid, and conjugate base for common acid-base reactions

Example 1: Write the products of the reaction of hydrofluoric acid and water, and identify the acid, Bronsted-Lowry base, conjugate acid, conjugate base, and the hydronium ion.

Be able to give the conjugate base for the common acids (remove H+), and the conjugate acids for the common bases (add H+)

Example 2: list the conjugate acids of ammonia ( (

). List the conjugate base of water (

hydrocarbonate anion HCO3- (

), water (

), and the chloride anion

), Hydrochloric acid (

), and the

). Finally, the hydroxide anion is the conjugate

_____________ of water.

b. Measuring the strength of acids worksheet (honors only) -Be able to write the equilibrium reaction and acid ionization constant for a given acid

Example 3: What is Ka for HCl and what does the equation look like?

32


-Be able to classify acids as strong or weak (>1 = strong; <1 = weak) (honors only)

Example 4. The Ka of an unknown acid is 2 x 10-5 M. This is a ______________ acid.

-Be able to identify the strongest and weakest acid from a list of Ka values (honors only) -Be able to label acidic and basic solutions as dilute/concentrated, strong/weak, acid/base. (honors only)

Example 5. A 3.2 M solution of hydrochloric acid is an example of a ________ ___________ acid.

c. [H+] and [OH-] calculations worksheet -Be able to use Kw to determine [H+] or [OH-]. (honors only; whole numbers for rest) (remember, some of these will require the use of a calculator)

Example 5. For an aqueous solution, if [H+] is 2.1 x 10-4 M, then [OH-] must be _______ M.

d. pH and pOH calculations (also known as the worksheet from Hell) -Be able to determine pH, pOH, [H+], and [OH-] when given one of those pieces of data

Example 6 : if [OH-] = 10-12 M, then the pH is ________, the [H+] is ____________, and the pOH is ________.

e. Titrations worksheet -Be able to write out common acid-base neutralization reactions

Example 7. Write the reaction between hydrobromic acid and lithium hydroxide.

33


-Be able to determine the concentration of an acid or base when titrated with a standard solution.

Example 8: Write a procedure for titrating an unknown acid.

Example 9. 323 mL of 2.1M NaOH were required to neutralize 414 mL of an unknown acid. The [OH-] concentration of the acid must be _______ M.

f. Polyprotic acids (honors only) -Know the chemical formulas of sulfuric, carbonic, nitric, and boric acid

Example 10: Please give the formulas for the following acids: Sulfuric__________

-Be able to write the complete equilibrium reactions for these polyprotic acids in water

Example 11: Write the three lines that show the complete aqueous equilibria for phosphoric acid. 1.

2.

3.

34