Instructor’s Resource Manual
LABORATORY MANUAL Sandra Chimon Rogers National University of Health Sciences With Contributions by Stephanie Dillon, Florida State University Barbara Mowery, York College of Pennsylvania
CHEMISTRY Eighth Edition Jill K. Robinson John E. McMurry Robert C. Fay
Table of Contents To the Instructor
v
1)
Measurement and Expression of Experimental Data
1
2)
A Submarine Adventure: Density Saves the Day
13
3)
Conservation of Matter
21
4)
Plop, Plop, Fizz, Fizz: The Mass Percent of NaHCO3
28
5)
Proof of Alcohol
35
6)
Empirical Formula of a Compound
42
7)
Pancake Mix as a Limiting Reactant?
48
8)
Redox Reactions in Voltaic Cells: Construction of a Potential Series
56
9)
Reactions in Aqueous Solutions: Strong Acids and Bases
62
10)
The Copper Cycle
68
11)
Atomic Spectra
75
12)
Colligative Properties of Solutions
82
13)
Building Molecular Models
92
14)
Calorimetry and Hess’s Law
99
15)
Gas Laws and Airbags
107
16)
Intermolecular Forces and the Triple Point of CO2
113
17)
The Purification of Water
120
18)
Kinetics: The Iodine Clock
129
19)
Photometric Determination of an Equilibrium Constant
136
20)
Analysis of Vitamin C in Fruit Juices By Titration
143
21)
Murder Solved by the Analysis of a Kiss
148
iii
22)
Entropy, Free Energy, and Chemical Equilibrium
153
23)
Electrochemistry: The Nernst Equation
160
24)
Qualitative Analysis: Anions
167
25)
Qualitative Analysis: Cations
173
26)
Qualitative Analysis: Cations, Anions, and Complex Ions
179
27)
Whodunit? A Forensic Investigation
186
28)
Chemical Structure and Smell
193
29)
Proteins, Carbohydrates, and Fats: Analysis of a Peanut
202
iv
To the Instructor: This manual is for you, the instructor. It was designed in a way that you are able to get insight into the labs and have a clear sense of purpose catered and designed for your students without you having to do an obscene amount of prep-work. I have included a section of notes, some insight, a great background, and solutions and also a rubric to ease every instructor’s troubles. The rubric will not only allow you to grade with ease and confidence but also allow you to quantitatively and qualitatively compare your students’ results with fellow colleagues from around the nation, if they are using the same lab manual. Another wonderful thing about this manual is if you have no assistance for grading your lab worksheets or if you do what I do and that is utilize the help of my dear husband, who knows nothing about chemistry, this manual and its solutions make it easy for someone to assist you in grading. In addition to ease of grading, the labs are designed in a way that you can easily transit from a worksheet format to a lab report. The manual is designed in a way that they if the students need the crutches, they are there. I wanted to show you that the students can learn without realizing that you are learning. The emphasis here is that chemistry experiments are not just your stereotypical beaker and Bunsen burner experiments. They can be fun, real-life based, and educational. The experiments are based on such topics from air bags to a murder investigation. There are real-life situations which utilize chemistry as a way to ask a question and solve it. Reemphasizing that the focus is you, the instructor, not only are these experiments more fun, the lab manual is designed to help you get through the experiment and the lab write-up. The lab manual is designed to have a well thought out, articulate an introduction to capture the interest of our students along with the instructors, a step-by-step list of instructions on what to do and why you are doing the experiments, to a nice follow-up which ensures critical thinking. The questions at the end of the experiment are designed to help you collect, interpret, and analyze the data. Not only will the students be questioning the data but they are also starting the means to writing up a thought-provoking chemistry lab report by simply following the format of the questions at the end of the experiment. Let’s not look at chemistry labs as that dreaded class everyone has to take, but get it out of its rut and let this manual be your guide to show the students that chemistry can be fun! Chemistry should be fun because without chemistry, we couldn’t have fireworks, electric cars, and makeup. Now let the fun begin. Let’s take what we are learning in the classroom and apply it in the lab. Warmest regards, Dr. Sandra Chimon Rogers Associate Professor of Physical and Natural Sciences Dean of College of Professional Studies National University of Health Sciences
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v
Experiment 1: Measurement and Expression of the Experimental Data Instructor Notes and Lab Preparation Each fall and spring semester a week after school starts, things are hectic, students are still registering for classes, and some sort of holiday interrupts the first week of labs. This allows the instructors only to check in the labs but then have an off week before the students are able to start performing experiments. Rather than allow the students to waste a full week of lab time, assigning this math and graphing review as the first experiment of the semester is a great way to refresh their minds and get them back into the swing of things. Part A is designed for the first semester, and Part B is designed for the second semester of general chemistry. As the check-in process is generally quick, at the end of the check-in day, I have each of my teaching assistants give a short lecture on the math involved.
Particular Points to Stress Scientific or exponential notation is used so often in scientific literature and calculation; it seems we sometimes forget how confusing it can be to someone dealing with it for the first time. I always stress that students should look at the values they calculate to make sure they make sense. For example, one of the most common mistakes students make when dealing with exponents is when they must change an exponent to add or subtract two exponential values. The process requires students “move the decimal” in the correct direction to “match up” the exponents. The most common mistake is the movement of the decimal in the wrong direction. So ask the students to check and make sure that the number resulting after the move still makes sense, that is, does it have the same value it did before the move? Simply plugging it into a calculator should do the trick. Another sticky point with many students is an overall lack of graphing skills. I have placed a brief Excel® tutorial at the end of the manual to encourage students to use this program or one similar to it to complete the graphing exercises. If you choose to have your students complete the graphs by hand, I understand the reasoning, but I would encourage you to consider asking for the graphs in both styles. The reality of the world today is that computers are everywhere. Skillful use of technical programs like Excel® is a must for scientific analysis. The most common mistakes that should be discussed with respect to graphing are (1) attempts to fit straight lines to data that do not fit y = mx + b and (2) irregular spacing of values on an axis. I often see graphs with axes that are marked at regular intervals with the values given as part of the problem. Markings of this sort always generate perfectly straight lines, which thrill the students, but give me migraines. Last but not least, the discussion we have about logarithms and the proper use of significant figures in logarithms is generally the first exposure students will have to the subject. Special attention should be paid to the introduction of this material.
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