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unit 3


How do we find out what everything is made out of?

Unit 3

What is a tomato, mustard leaf, and a strawberry made out of?

L

ook 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: Separation Lab Lesson 2: Leaf Lab Lesson 3 Matter Lecture Lesson 4: Review Lesson 5: Matter test.

A Liquid Chromatograph-Mass Spectrometer (LCMS) can take a complex mixture, separate it, and identify each substance. Shown above are the major components of a tomato (a), mustard leaf (b), and a strawberry (c), with some individual substances (d-f) shown below based on their mass spectrum. Learn more by clicking on the image.

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Table of contents

Introduction

Matter

contents

Classifying matter

Leaf lab

Properties of matter

Phases of matter

Separation/identification devices

Separation/identification ws

separation lab

How to Ace the Matter Unit

Classifying matter ws

Purifying matter

Liquid crystals

summary ws

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Separation Lab Some separation methods to consider

Chemists typically spend more than half of their time purifying substances- separating them into their individual pure components. As a chemist it reminded me of cleaning up a mess at home. 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:_____sugar__________ 2: ____salt__________ 3: _______iron filings_______ 4: _____corn kernels_________ 5: ____pebbles__________ 6: _____granular aluminum_________

Separatory funnel

filtration

Your goal is to separate all ingredients of your mixture quantitatively, and analyze your res ults. You will be graded based on your choice of methods, your report, and percent error: how close your amounts are to the actual amounts provided.

forceps

evaporation

decant

boiling

Tonight: Discuss this with your partner and come up with a plan. Write it as a diagram on the next page. 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.

chromatography

Invent your own

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

Most common errors: -No separation or only partial separation of salt and sugar. -Samples still wet after overnight drying.

salt Method sugar

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Separation lab (continued) Homework: Draw a neat diagram outlining your separation procedure, using the scheme shown on the following page. Note that you will have 60 minutes of class time only over two days to complete your separations.

Sand is an ingredient, but is not actually pure, as it contains hundreds of substances in addition to quartz (SiO2)

Once you have the stamp of approval, begin your separations. Time your work so that any sample drying takes place overnight. When you are done place each sample in a labeled plastic bag, and ieach ndividual bag in a final plastic bag- your instructor will model it for you. You will be graded based on the purity and amount of each sample. Fill in the data table and complete the Analysis section below.

Separation Lab: Data Mass of mixture

________ g

Mass of component 1 (__________)

________ g

Mass of component 2 (__________)

________ g

Mass of component 3 (__________)

________ g

Mass of component 4 (__________)

________ g

Precision: 1 point off for each percent error

_____ /10

Mass of component 5 (__________)

________ g

______ 10

Mass of component 6 (__________)

________ g

Sample Purity (by inspection)

Total mass of separated components

_______ g

Neatness and accuracy of report and analysis

_____ /10

Total

_____ /30

Percent Error

________ %

Your Score

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.

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Lab 3.2

Toxicodendron radicans (Poison Ivy)

The matter all around us is rarely in a pure

form; most of what is around us are mixtures. Perhaps the most complex mixtures are those in living things. To understand what is in a mixture we must separate the individual substances contained in a mixture.

Carotenes: Gold to Orange O

In our very first experiment you each planted a seed and by now you should have several leaves. The goal of this experiment is to isolate some pure substances from that leaf. If you have need to, bring in some fall leaves from home.

O

Xanthophylls: Light Yellow O O

O

O

N

O

N

Every leaf contains 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.

Mg

N

N

H O

Chlorophyll A: grass green

Background:

Light is a form of electromagnetic radiation. The different colors of light we see are a combination of many reflected wavelengths of light that vary from 380 - 750 nm (nanometers) in length. Each wave also has a specific amount of energy, where shorter wavelengths have more energy than longer ones. Organic compounds with more than seven alternating double bonds absorb this visible light in the visible wavelength varying from yellow to red. Compounds that are blue or green typically have not only extended alternating bonds, but also heteroatoms (atoms other than carbon and hydrogen). This includes chlorophylls A and B, which absorb that light for the plant to use. Note that we can make some rough predictions as to the color of a substance based on it’s chemical structure. O O

O O

Chlorophyll B: Olive Green

O

N N

Mg N

N H O

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Leaf Lab (continued)

Each plant contains substances unique to that plant alone. Even today scientists are isolating new substances from common plants and publishing their results. Some of these plant substances have been known to benefit us (like quinine for malaria) or hurt us(like paly toxin form Hawaiian coral). Leaf Chromatography: Procedure: Grind up a few leaves using a mortar and pestle and enough acetone solvent to make a thick mush. Using a toothpick , draw a thin, straight line across the bottom of your chromatography paper as shown below. To avoid streaking don’t paint edge to edge. Put some chromatography solvent (95% hexanes, 5% acetone) in a jar so it just covers the bottom. Carefully place the paper in the jar so the solvent is below the line. Let it rise up the paper; the higher the better. Don’t let it go all the way to the top. Staple your chromatogram to this sheet and answer the following questions.

1. Identify each separated band and estimate its Rf value.

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.

2. Repeat your experiment using 1:1 hexanes/acetone, and pure acetone. Record your observations below.

Answer the following questions at home, or in class if time allows. You should go online briefly to find your answers. 2. Describe in your own words the molecular basis for chromagraphy…how does it work? Source: How chromatography works:

3. Why did acetone create the results you observed?

Molecule Carotenes Xanthophylls Chlorophyll A Chlorophyll B

Rf value 0.8 0.7 0.5 0.45

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Matter Unit 3

Our essential question: How do we find out what everything is made out of? A good place to start: Classify it.

Matter Element, molecule, or mixture?

gold element

ocean mixture

milk mixture

copper glass element

molecule

Think of an example of each. Element:

Molecule:

Mixture:

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

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Nothing is pure in this world. What can we say about mixtures?

Looks pure but isn’t

doesn’t look pure

One thing visible

Multiple things visible

homogeneous “a solution”

heterogeneous “a mixture”

Either way it’s still a mixture… until it is separated we don’t know much about it.

Solutions: solid-liquid: Salt water solid-solid: brass;steel

Gas-gas:

air

Gas-liquid: soda liquid-liquid: Gasoline; vinegar

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

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• Purification: How to separate mixtures.

• You have

• want • sand • sugar • oil: • oils pure: • Technique:

• decant • filter

• All.

• crystallize

• distill • chromatograph

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

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Physical vs. Chemical Properties of Matter Stays the same

New substance(s) formed

Chemical Properties include

flammability

rust

ductility

Physical Properties include:

Melting point

color

density

Boiling point

magnetism

crystallinity

malleability

Refractive index

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

luster

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Extensive and Intensive Properties • amount-dependent

Doesn’t matter how much

• ”extent”

ex

in mass

Melting point

ex

density

in

Refractive index

toxicity

in

crystalline

amorphous

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

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Phase Changes

hot

gas condense

boil

deposit

sublime

liquid melt

freeze cold solid

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

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5 states of matter hot

Assumes Fills Shape of Container? Compressible? Container?

State?

plasma

cold

no

no

??

gas

Yes

yes

yes

liquid

Yes

no

no

Liquid crystal

YesBut ordered

no

no

solid

no

no

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

no

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Liquid crystals and plasmas Ordered liquids

charged gases

Nematic liquid crystal:

Linear alignment Smectic liquid crystal:

Planar alignment

L2: End matter ď Š

Coming next: the atom

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

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Modern Separation Methods (L1, honors only) Still in Use

Layer separation

distillation

Paper chromatography

filtration

crystallization

Vacuum distillation

Thin layer chromatography

Spinning band distillation

Gas chromatography

High performance liquid chromatography (HPLC)

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Classical Identification Methods (L1, honors only) Still in use

Melting point

Boiling point

Modern Identification Methods (L1, honors only

Flame ionization

Nuclear magnetic resonance spectroscopy (NMR)

Infrared spectoscopy

Mass spectrometry

All-in-one LCMS

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ws 3.1

Classifying Matter What is everything made out of? Our essential question for this course: To say that the universe is made out of matter is true, but doesn’t provide much detail. It would help to classify mater.. Let’s start with elements. 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 bonded together 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.

What is everything made out of?

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 be fluoridated 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 few…this 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).

What is a diamond ring made out of?

matter

element

molecule

mixture

Classify the 19 materials on the next page, then check the answer key to see how you did.

*You

should be aware that many texts differentiate between molecules and compounds. In this class we won’t go there. If you’d like to see the confusion that it can lead to, click here or here.

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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:______ 2. A molecule in front of m:________ 3. A mixture in front of me:________ 21 (L1, honors only) Use the following 6 definitions to make a classification chart similar to the one at the end of unit 1. A sample to get you started is at the bottom right of page 18. Matter: Anything with mass and space. Element: A substance with a fixed number of protons Molecule: Atoms bonded together Compound: Different atoms bonded together Mixture: More than one substance Substance: A pure form of matter each of the 7 words below on your chart as examples. Consider if some should go in more than one place.. Also ask yourself if pure elements are bonded together. Oxygen (O2) Water Iron Carbon Diamond Graphite Sodium chloride

Humans love to classify everything.

Matter classification chart (L1, honors only)

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ws3.3

A walk on the beach

Introduction to Matter Summary Worksheet

Crystalline Amorphous Matter Substance Compound Solid Gas Heterogeneous

Homogeneous Liquid crystal Liquid Sublimation Deposition Boiling Melting Condensation

Chemical Physical Silicon Oxygen Ozone Precise accurate

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. L1 and honors students know that if I could prepare a solution of my substance I could puriy it and have the minor impurities identified using a single machine known as a ___________. But I’m pretty sure I know what it is already. My substance is______________.

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ws3.4

I need it Pure

Modern Purification and identification methods worksheet After listening to the matter slideshow, especially the last two slides on modern methods of sample purification and identification, answer the questions below using some but not all of the words below Layer separation Simple distillation Fractional distillation Spinning band distillation Recrystallization Filtration Paper chromatography Thin layer chromatography

Gas chromatography High performance liquid chromatography Melting point Boiling point Flame ionization spectroscopy Infrared spectroscopy Nuclear magnetic resonance

Mass spectrometry Liquid chromatograph-mass spectrometer

Place an I in front of each term above that refers to compound Identification, and a p in front of methods used for Purification 1. Which method is best for separating oil from water? __________________________ 2. Which method is best for separating two liquids whose boiling points only differ by one degree Celsius? ________________ 3. Which method is appropriate to separate 5 mg of a solid organic substance? _______________ 4, I’d like the elemental composition of a pure metal. A good method would be______________ 5. I’d like to separate a separate a sample of Martian Air into it’s individual components…a good choice would be:______________________________ 6. This method of sample identification is used for organic compounds, and although it provides a nice “fingerprint of the substance, has been largely replaced by more informative methods such as___________ 7. This method of sample identification creates predictable peaks based on the composition of the elements next to the point in question._________________________ 8. This method of sample identification produces a molecular ion which is a good measure of the molecular weight of the substance._______________________________________ 9. This is an old method of purification still in use, gives incredible sample purity, and was used in the rock candy experiment __________________________________ 10. This will do for separating oil and water __________________________________ 11. For the separation of complex mixtures which can be dissolved in a solvent, this method is hard to beat._________________________________________ 12. Used in the leaf lab, this method will separate a crude sample into many individual substances but is rarely used professionally. ____________________________ 13. This is the ultimate solution: it will separate and identify just about any solution, no matter how complex.___________________________________

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How to ace the Matter test

Howtoaceitunit3

In this our third unit we learned how to purify and classify matter. Matter in its natural state is a mixture of substances, and to study them we purify and identify them, and determine their properties. The mixtures may look pure (homogeneous) or many things may be visible (heterogeneous). The pure substances occasionally are composed of only one element, but more often are molecules that consist of multiple elements bonded together. There are a nearly infinite number of individual substances on earth, and chemists have learned how to mak evirtually any new substances (though not always very quickly) of their own design.

We have seen how substances may be classified based on how their atoms are arranged (for example functional groups such as aldehydes, ketones, etc.). They may also be grouped into their 5 physical states, their physical, or their chemical properties. A chemist spends the majority of his or her time purifying mixtures, and we spent some time doing that. We used basic techniques such as decanting, filtration, distillation, and chromatography to isolate some pure substances from a mixture. L1 and honors students explored the modern equipment used for separations including high performance liquid chromatographs and spinning band distillation devices. All students learned basic methods to identify pure substances such as odor, melting point, and conversion to known compounds. L1 and honors students also learned about modern spectroscopic methods to identify substances such as nuclear magnetic resonance (NMR) spectrometers. Finally, they had a glimpse at the future with some state of the art devices that can purify a mixture and identify each substance in it such as a LC-MS (liquid chromatograph-mass spectrometer). To ace this test be sure to understand the packet, including all lab experiments, slides, and worksheets. Go online and watch the screencasts of the slides if necessary. Be ready to separate a mixture if given one. Take a brief look at the first two units, since they are fair game on a test. Review your notes from your lab notebook, including all demonstrations and chalk talks. Finally consider the significance of the long term experiments we have been monitoring- the rock candy lab, and the seed lab. In our next unit we will zoom in enormously from our macroscopic view of matter and will ask ourselves what the smallest building blocks of matter are- this is the atom unit coming up next. 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.

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1. What is matter? Matter is_____________________

14. How to separate mixtures a. Sugar from sand

2. What is a substance? A substance is a __________ _________ or ____________

b. Iron from sand

3. What is a physical property?

d. Blue ink from black ink

c. Water from the ocean

4. What is a chemical property?

15. What is an element?

5. How could I separate sand from aluminum powder?

16. What is a compound?

6. What are the 5 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?

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 propanol, C3H8O using both a structural and skeletal formula.

10. Describe the six conversions of matter states (boiling, melting‌)

11. What is the law of conservation of mass? 21. Draw two isomers of butane, C4H10, 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 (______________).

22. To put this unit in perspective, modify the conceptual diagram at the end of unit 1 to include the main concepts of the matter unit.

22. What is an atom? This is our next unit.

urushiol

Toxicodendrons radicans (poison ivy)

Poison Ivy (Toxicodendron radicans, shown at left) produces the urushiol class of allergens, including the one shown

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c. matter 2011 unit 3  
c. matter 2011 unit 3  

matter unit

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