DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
WHAT ARE THE TYPES OF MATTER?
1. The stuff of the physical world can be divided into three types. The basket at this station
contains vials of materials representing all three types. Take all the materials out of the
basket and line it up on the desk. The names and chemical formulas are on the vials. Read
the labels and examine each sample and separate them into three groups. HINT: The labels
provide the key to the division of types!
In the spaces below write the names of each member of the group and a brief description of
each.
Group I
Group 2
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Group 3
DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
2.
What does the word “elementary” mean?
Which of your three groups might be called “elements?” ______________________
Label their group on the previous page.
What does the word “compound” mean? (as in the sentence, “The problem was
compounded by the fact that the man lied.”)
Which of your three groups might be called “compounds?”
Label their group on the previous page.
What does the word “mixture” mean? (as in the sentence, “The room was filled with a
mixture of people from all over the world.”)
Which of your three groups might be called “mixtures?” ___________________ Label
their group on the previous page.
3.
Select the vials labeled Cu and S and O2 and the vial labeled CuSO4.
What do they have in common?
How are they different?
What can you conclude about the properties of elements when they are combined into
compounds?
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
4.
a)
Place about a spatula-full of CuCO3, cupric carbonate, into a pyrex test tube and
clamp it to a ring stand. Light the Bunsen burner (ask for help if needed) and heat this
chemical strongly. Do not put your face near the opening of the tube. After it has been
heated for about a minute, light a wooden splint and place it in the mouth of the tube.
(Do not drop it into the tube). Make sure the splint is out before disposing of it in the
trash.
Heat the tube for another minute or so, allow it to cool and fill in your
observations below.
Color of CuCO3
Result with burning splint
Color of what remains in test tube after heating
What do you think happened?
____________________________________________________________
b)
Place about spatula-full of NaCl (table salt) into a small beaker. Add about 20
mL of water and stir with a glass rod until all the salt is dissolved.
Describe what you see
Pour half of this mixture out into the sink, and heat the rest strongly on a hotplate. While
it is heating hold a glass plate across ½-way across the top of the beaker for about 15
seconds. Continue heating mixture until no further change takes place. Record the
observations below.
What appears to be on the glass plate?
Are there any signs of salt on the glass plate?
What remains in the beaker?
How is the heating you have just performed (other than the fact that it was done
on a hotplate) different from the heating in part a) of this activity? HINT: Think
about the result!
Are there any questions you would like to ask?
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
SEPARATING SAND AND SALT
Let’s look at one of the types of matter and how to separate the components.
1. Obtain a small amount of sand and salt mixture.
2. Try to separate the sand and salt with your fingers. What physical property are you using
in this method of separation? Is this possible? Is this practical?
3. Dissolve the salt and sand in water by adding the mixture to 25 mL of water. Stir. What
happens? What physical property is different for the sand and salt?
4. Does stirring harder change anything? Try to remove the undissolved solid by filtering.
5. Set-up a filtration apparatus as shown here.
6. Pour the mixture through the filter paper in the funnel. The liquid
that pours through is called the filtrate.
What does the filtrate contain?
Is it homogeneous or heterogeneous?
The material remaining in the filter paper is the residue.
What is the residue made of? How do you know this?
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
7. Place the filtrate in an evaporating dish. Heat the dish until all the water has evaporated.
or:
Place a little of the filtrate on a watch glass in a sunny location or on an overhead
projector for a while and observe.
What is left? How do you know this?
What physical property was used in this separation?
Questions:
When deciding on how to separate mixtures, why is it useful to know a lot about the
characteristics of the parts of the mixture? Name all the properties that were used to aid
in the separation salt and sand.
What kind (physical or chemical) of changes were used to separate the mixture?
Additions to Sand/Salt Separation (For your classroom)
1.
Explore the physical properties of sand, salt and water before the separation: color,
solubility in water, boiling point (or melting point).
2.
Try other separations
a. Iron filings and sand (or salt or sugar) with magnet
b. Baking soda (water soluble) and flour for making cookies
c. CuSO4 copper sulfate (flue and water soluble) and sand
d. Oil and water (2 layers)
e. Muddy water
f. Kool-aid (unsweetened)
3.
Determine the % salt (or sand) in the mixture. To do this, weigh the mixture before
adding water. Weigh the recovered salt (or sand). Remember: % = (part/whole) x 100
% salt = grams of salt recovered x 100
grams of mixture
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
4.
What errors in measurement or technique might lead to getting too high or too low of a %
composition of each component?
NOTE: If sugar is used instead of salt in the mixture with sand, the sugar may burn
heat is applied to boil away the water.
Alternatives to Doing Actual Sand/Salt Separation
1. Prepare a handout with blanks that students can complete as you demonstrate or talk
about the lab. The blanks could be for the procedures used (a) or what is separated at
each step (b).
a.
b.
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as
DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
Questions:
1. Can you think of other mixtures that can be separated this way?
2. Can any of these techniques be used at home? How?
3. Name some household activities that are physical separations.
Hints: What do you do after you boil spaghetti?
Before you eat watermelon?
What was the original purpose of a wine decanter?
Degreasing gravy?
Drying your hair?
How would you get pebbles out of a sand box?
How are bugs and dirt removed from swimming pools?
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
CHROMATOGRAPHY
Is the color we see in felt tip marking pens just one color ink, or are many colors mixed together?
We can find out using the separation technique of chromatography. It uses the differences in the
relative attraction of substances for a solvent (moving phase) and another surface (stationary
phase). In paper chromatography, the components of a mixture to be separated are absorbed or
attracted to the surface of the paper. As the solvent moves up the paper by capillary action, it
passes over the mixture. Any component that is more attracted to the solvent will move up with
the solvent. Since different components will have differing degrees of attraction the components
will separate on the paper.
Let’s try it out!
1. Obtain a strip of chromatography paper.
2. Place a small line of the ink you are testing about 2 cm from the bottom of the paper.
With a pencil draw a line 10 cm from the ink line.
3. Get a paper cup (or beaker) and fill it up about 2 cm from the bottom with water. Make
sure the height of the water is below the height of the ink line.
4. Carefully unfold a paper clip and poke it through the top of the paper so that the end of
the paper will just hang in the water.
5. Hang the paper in the water and cover with a piece of aluminum foil or plastic wrap.
Allow the water to move up the paper until it has gone to the 10 cm mark.
6. Remove the paper and wire and hang them in a dry cup for a few minutes (or dry with a
hair dryer, if one is available).
7. Observe how many different color inks are in your ink on your chromatogram. Measure
the distance from your original line to the middle of each colored line in cm and record
below.
Line
Color
Distance
#1
#2
#3
8. Compare your chromatogram with that of others. What has been separated?
How do you know that?
Which component was most attracted to the solvent?
Which component was most attracted to the paper?
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
As a class:
1. Make a chart of each color and distance by checking the results of others in the class.
Color
Distance (cm)
Yellow #1
Yellow #2
Blue #1
Blue #2
Red #1
Red #2
Green #2
Pink #1
Pink #2
Black #1
Black #2
Questions:
1. Are all the blue inks or red inks the same? Why or why not?
2. Does one color travel farther than another?
3. Do two or more different pens have the same ink components? Explain.
4. Of what practical value is the technique of paper chromatography?
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
5. Can you think of how you might use your chromatogram to figure out how much of
each compound was in the mixture?
Note: A paper towel could be used in place of “official Chromatography paper.”
For older students, TAG classes, or simply to incorporate measurement and math into this
activity, consider the following:
Additions/Changes to Paper Chromatography of Felt-Tip Markers:
1. Incorporate calculation of Rf.
Rf =
distance line travels from origin
distance solvent (H2O) travels from origin to solvent line
This ratio should be the same value for the same ink component even though the solvent
may have gone only 5 cm in one separation and 10 cm in another. Actual
chromatographic analyses always include Rf. These values can be used to identify
components of a mixture by comparison to known values.
2. Try other solutions:
a. Concentrated unsweetened kool-aid
b. Food colorings
3. The chlorophylls (green), xanthrophylls (yellow), and carotenes (orange) in spinach can
be separated nicely. However, water will not work. The extracting solvent and
developing solvent must be ether, chloroform, or methylene chloride. This is suggested as
a demonstration provided adequate ventilation is available (or you may go to sleep).
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
AN INVESTIGATION OF CHEMICAL REACTIONS
Pre-Lab Questions
You are about to perform a number of chemical reactions. How, how will you know that a
reaction is taking place? List and explain some of the things you expect to observe as chemical
changes occur.
Let’s suppose that you mixed two colorless, clear solutions and there was no visible change.
Could a chemical reaction have occurred? Explain.
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
This activity will give you some experience with various chemical reactions or chemical
changes. You will use your observational skills to describe some physical properties of the
reactants (starting materials) and products (substances formed as a result of a chemical change).
You will practice writing formulas and balancing equations. As you become familiar with the
types of reactions, it will be easier for you to make reasonable predictions about what will
happen when unfamiliar substances chemically change.
GENERAL PROCEDURES
Identifying Gases
Before you begin the investigation you need some simple procedures for detecting gases that are
products in a reaction since they may have no odor or color. We employ a wooden splint which
can be ignited. For this reason, these tests are called splint tests. You light the splint with a
Bunsen burner. To determine which splint test is appropriate you should look at the reactants
and predict what gas is likely to be formed.
Hydrogen
Place a burning wooden splint near the mouth of the reaction
container (usually a test tube). If there is a “pop,” like a miniexplosion, the gas produced is probably hydrogen. Hydrogen is the
least dense gas and escapes quickly when it is generated. It may be
helpful to put your finger over the end of the tube for 10-20
seconds to trap some gas for the test.
Oxygen
Place a glowing splint (lit and blown out) into the mouth of a test
tube. If the splint relights, the gas is probably oxygen.
Carbon Dioxide
Place a burning splint into the mouth of the test tube. If the splint
is extinguished, the gas is probably carbon dioxide.
On the next page you will find a series of specific instructions for five chemical changes. For
each of these reactions, please follow the procedure below.
 Do not use more chemicals than called for and dispose of all end-products in the properly
labeled waste containers.
 For each activity, observe and record the following information on the data sheet after the
specific procedure:
Reactants
Description of Reactants:
Observations During
Reaction:
Description of Products:
List names and formulas of all starting materials
describe the physical properties of the reactants (color,
state, luster, mass (if asked for), density…)
describe what you see as the reaction takes place (color
changes, gas formed, solid produced, heat evolved…)
describe the physical properties of all materials produced in
the reaction.
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
Reactants
Description of
Reactants
Observations During
Reaction
Description of
Products
mercury (II) oxide
red solid
solid changed to
silver, metallic
form silver, shiny
liquid
or HgO
liquid; during splint
test glowing splint
colorless gas
relit
 Write a brief statement describing what you think happened.
 You can try to write the chemical equation for the reaction, but we will do this together
during the discussion.
 We will work out the type of each reaction during the discussion.
SPECIFIC PROCEDURES
1. Place a test tube in a test tube rack. Add about 10 mL of dilute hydrochloric acid, HCl, to the
tube. Clean a 2 cm piece of magnesium ribbon with steel wool until shiny. This removes
any oxide coating that may interfere. Add the magnesium to the HCl. Use a splint test to
identify one of the products.
2. Using crucible tongs, place a 2 cm piece of magnesium (Mg) ribbon in the hottest part of a
Bunsen burner flame. Do not look directly at this reaction as it happens since the bright
light may affect your eyes.
3. Place about 5 mL of CoC12(aq), cobalt (II) chloride solution, in a test tube. Add 5 mL of
Na3PO4 (aq), sodium phosphate solution. The water does not take part in the reaction.
4. Place about 20 mL of CuSO4 (aq), copper (II) sulfate, in a small beaker. Scrape the surface
of an iron nail with steel wool. Add the nail to the solution and wait about 2 minutes. Using
tweezers or tongs, carefully remove the nail and place it on a paper towel.
5. Place a small amount (to cover the curved bottom of the test tube) of potassium chlorate,
KCIO3, into a pyrex test tube. Heat the bottom of the tube in the hottest part of the Bunsen
burner flame. Use a splint test to help identify one of the products. Heat until you no longer
get a positive splint test.
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DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
AN INVESTIGATION OF CHEMICAL REACTIONS
Reactants
Description of Reactants
Observations During
Reaction
1
Chemical Equation
Word Equation
Reaction Type
2
Chemical Equation
Word Equation
Reaction Type
3
Chemical Equation
Word Equation
Reaction Type
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Description of Products
DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
Reactants
Description of Reactants
Observations During
Reaction
4
Chemical Equation
Word Equation
Reaction Type
5
Chemical Equation
Word Equation
Reaction Type
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Description of Products
DAY 3
CHEMISTRY INSTITUTE FOR TEACHERS
WHAT DOES STRONG HEATING DO TO MASS?
What are some of the things that come to mind when you think of burning?
In this activity, you are going to strongly heat some steel wool. Steel wool is mostly made of
iron. You will mass the steel wool before you heat it and mass it again after you heat it.
Pull a small piece of steel wool off the larger piece, wad it up into a loose ball, and place it on a
clean watch glass. A watch glass looks like a big contact lens. Mass the dish and steel wool
carefully on the platform balance.
Color of the steel wool
Mass of watch glass and steel wool
g
Light the Bunsen burner and point the flame at the steel wool from the top. Be careful not to
blow the steel wool off the watch glass. Keep doing this for about 3 minutes. Allow the steel
wool to cool off for about a minute and then mass it again.
Color of steel wool after heating
Mass after heating
g
What happened to the mass of the steel wool as a result of the heating?
What explanation can you make for this result?
Are there any questions you would like to ask?
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