Alka Seltzer® Poppers
Alka Seltzer is sometimes taken for acid indigestion. This over-the-counter medication is taken differently than most
others since it is added to water before ingesting, rather than being “washed down” with the water. Let’s investigate this
addition of Alka Seltzer to water.
Materials
5 (or more) Alka Seltzer® tablets
1 35-mm film canister with lid
ice-cold water
(optional) 1/4-cup measure
clear container such as a plastic cup or glass
teaspoon measure
very hot tap water
room-temperature water
tablespoon measure
safety goggles
Safety
Goggles are recommended to protect your eyes from possible flying debris in this activity. Do not use water hot enough to
scald.
Exploration
1. Determine and record the active ingredients of Alka Seltzer tablets.
2. Add about 1/4 cup of room-temperature water into a clear container. Add an Alka Seltzer tablet to the water and
observe. Keep the solution for use in Step 3. Describe what happens. What role does water play in this system?
What is the identity of the most obvious product of this chemical change? Write the chemical equation which
describes the reaction that has occurred.
3. Place 1 tablespoon of the solution from Step 2 in the film canister. Add half an Alka Seltzer tablet to the canister
and immediately put on the lid. Hold the canister upright and away from your face. What happens? Explain your
observations.
4. Design and perform an investigation to determine if the observations in Step 3 are reproducible. What did you do?
What did you find out?
5. Repeat Step 3 with room-temperature water which has not had an Alka Seltzer tablet dissolved in it already. How
do the results compare with those in Step 3?
6. Rinse out the canister and place 1 teaspoon of room-temperature water in it. Add half an Alka Seltzer tablet to it and
immediately put on the lid as before. Compare your observations with those in Step 5 and explain any similarities
and differences
7. What do you think would happen if you added 2 tablespoons of water to the canister before adding the Alka
Seltzer? Try this variation using the same technique and explain your observations.
8. Design an experiment to determine the impact of changes in the temperature of the water on the system. Do not use
water hotter than hot tap water or colder than ice water. Describe what you did and your observations. Explain
what you observed.
9. Which trial is the control, the one to which the other trials are compared? Why is the number of variables changed
important? What other variables might be studied in this system?
Think About It
What are the effects of changing the volume of water and the temperature of the water used in the investigation?
© 2013 Terrific Science
Burp Bottle
Have you ever burped before? Burping is caused when there is an accumulation of gas in the digestive system. The “burp”
occurs when the gas is released through the mouth. You can construct a “burp bottle” to imitate this action. Try this
activity to find out how.
Materials
2 plastic soft drink bottles of the same size
(optional) narrow-necked glass (or other rigid) bottle
water
(optional) food color
shallow tray or sink
1 of the following 2 sets of materials:
Set 1
potato
tape
8-inch piece of wire
3-inch piece of rigid plastic tubing (aquarium tubing), or barrel of a Bic® pen (can try
another brand that has a removable tapered end)
Set 2
2 one-hole #3 stoppers
3-inch piece of rigid plastic tubing that fits tightly into the one-hole #3 stoppers, or barrel
of a Bic pen (can try another brand that has a removable tapered end) and tape
Getting Ready
1. Cut one of the soft drink bottles to make a funnel as shown in Figure 1.
2. Half-fill the uncut bottle with water.
3. Use one of the two connectors described below to create an airtight seal between the funnel and the uncut soft drink
bottle.
Potato connector:
If you are using a pen barrel that has a hole in the side, wrap tape around the barrel to cover up the hole. Carefully push
the rigid plastic tubing or pen barrel all the way through the potato. If any potato (that would restrict air or water flow)
becomes lodged inside the tubing, use a wire to push it out. Slide one end of the tubing into the mouth of the funnel all the
way up to the potato and gently screw the potato onto the threads of the funnel. Lower the other end of the tubing into the
mouth of the uncut bottle. Screw the potato onto the threads of the uncut bottle as you did with the funnel. (See Figure 2.)
Stopper connector:
Exploration
1. Place the apparatus in a shallow tray or sink. Fill the funnel 3/4 full with water (colored water is easier to see). Give
the half-filled bottle a slight squeeze. Watch for several minutes. What do you observe? Explain your
observations.
2. Gently unscrew the potato connector from the bottle (if using the stopper connector, twist to remove). Pour water
out of the bottle until it is again only 1/2 full. Screw the potato connector back onto the bottle (if using stopper
connector, twist to insert) and fill the funnel with water. Do not squeeze the bottle to start the burp. Does it to burp
on its own? (Don’t wait more than 3–4 minutes.)
3. Experiment to determine the minimum amount of water in the funnel and the minimum amount of water in the
uncut soft drink bottle that is needed for the burp phenomenon to begin without squeezing the bottle. What is the
importance of water in these two locations? Why is it important that all seals be airtight?
4. Try to make a burp bottle using a glass (or other rigid) bottle instead of the uncut soft drink bottle. Why were you
able (or not able) to get it to burp?
Think About It
What factors are responsible for the behavior of a burp bottle?
© 2013 Terrific Science
Chemistry of Solutions
Do you know how to make a solution? Can you determine the concentration of the solution that you made? How does
your solution behave? Try the following activity and find out.
Materials
table salt (NaCl)
water
cup measure
tablespoon measure
wooden spoon or wooden stir stick
several Styrofoam cups
thermometer (as used in making candy)
sauce pan
Exploration
1. Place 1 level tablespoon of table salt in a Styrofoam cup. Add 1/2 cup water to the cup. Mix thoroughly. Is this a
saturated solution? One tablespoon of table salt weighs approximately 12 grams. There are approximately 240 mL
in a cup.
2. Heat 1 cup water in the sauce pan until it is boiling. Suspend a thermometer in the water and record the temperature.
Add 1 tablespoon salt to the water. Do not remove the water from the heat. Mix the solution with the wooden
spoon or stir stick, never the thermometer. Record the temperature after it levels off. Explain your results.
3. Fill a Styrofoam cup with crushed ice. What do you think the temperature of ice is? Hold the thermometer in the ice
and record the temperature after it levels off. Place 3 tablespoons salt in the cup. Stir with the spoon or stir stick.
Observe the thermometer. What happens? Why?
Think About It
Why is it important that we understand solution chemistry? What are the applications of what you have seen in this
activity?
Chromatography on Paper
We like to make colors an important part of our lives. That’s why manufacturers make products in a variety of colors.
Have you ever wondered how these colors are created? We see a myriad of colors all around us, and many of them result
from a mixing or blending of other colors.
Colored markers are something we commonly use. A single color of marker may contain many different pigments. You
can probably make some guesses as to what colors of pigments are contained in marker colors such as green, orange, and
purple. How about black and brown? In this activity you will see for yourself. You may be surprised by your colorful
results.
Materials
several brands and colors of water-soluble markers (Vis-à-Vis® work very well; try to include black, brown, and green)
coffee filters
scissors
2 glass containers (plastic can be substituted if acetone is not used)
2 adhesive labels (or paper and tape to make your own)
plastic wrap or sandwich bags
water
one of the following:
rubbing alcohol (70% isopropyl alcohol)
acetone-based nail polish remover or hardware product
Safety
If you are using acetone, wear eye protection and avoid extensive or prolonged skin contact or inhalation. In addition,
avoid spilling acetone on your clothing or other fabrics.
Getting Ready
1. Squares : Cut two 2-1/2-inch x 2-1/2-inch squares out of the coffee filters. Using an accordion-style fold (so the
square will be free standing), fold each square into four or five sections (depending on the number of
colors/brands you are testing).
2. Ink dots : Place a different color of ink dot (about 1/2 cm in diameter) on each folded section of one square, about 1
cm from the bottom. Mark the other square in exactly the same sequence. You want to be able to readily compare
the squares when you are done. (See Figure 1.)
3. Solvents : Label one container “water” and the other either “isopropyl alcohol” or “acetone,” depending on which
one you are using. (Review the safety section about the use of acetone.) Pour about 1/2 cm of each solvent into
the appropriately-labeled cup.
Exploration
1. Carefully place a marked paper square (so it is free-standing) in each container. (If the solvent level touches the
dots, pour out some of the solvent and prepare another square with ink dots.) Cover the containers loosely with
plastic wrap or part of a sandwich bag. What is the purpose of doing this?
2. Observe the squares. Describe what the solvents are doing. What does this indicate about the solvents? What is
happening to the ink dots? Explain in terms of attraction.
© 2013 Terrific Science
3. Allow the chromatograms to develop until the solvents are about 1 cm from the tops of the squares. Remove the
squares. Use a pencil to write the solvent used on the dry part of each square. Now compare the chromatograms
and describe how they are alike or different.
Think About It
What are some of the factors that affect the usefulness of chromatography as a separation method? If a paper
chromatogram of a red dye shows a smear of pink, is this conclusive evidence that the dye is a mixture? Explain.
Diet versus Regular Soft Drinks
Cans of soft drinks are so common that many people have done much of this exploration without realizing it. You, too,
have probably cooled soft drink cans in ice water for a picnic. Here is your opportunity to see if you can make some
generalizations about their behavior in water.
Materials
1 12-fl oz (355 mL) aluminum can of diet soft drink, unopened
1 12-fl oz (355 mL) aluminum can of regular (non-diet) soft drink, unopened (use same
brand as the diet soft drink if possible)
container of water large enough to totally submerge both beverage cans in an upright position
measuring cup calibrated in mL
(if available) plastic, glass, or steel containers of diet and regular soft drinks of equal volumes,
unopened (Use containers made of the same material.)
Safety
Do not use water hotter than that from the tap since very hot water can cause the containers of soft drinks to explode, as
well as cause severe burns.
Exploration
1. Holding the unopened cans in an upright position, submerge both cans in the container of water. Let go and record
their orientations and whether they sink or float.
2. Repeat Step 1, but release the cans in a horizontal position. Record your observations. Explain any changes in
orientation of the cans.
3. What property of matter accounts for the cans floating or sinking? How does this property differ for each soft drink
can? If each container is made of aluminum and occupies the same volume, what do your observations say about
the mass of the contents? Read the content information on the cans. What, if any, are the differences in
ingredients?
4. With the measuring cup, measure the volume of the liquid in each can. How do these volumes compare to the
volume of the can? How do you think the densities of the liquids compare? What would have to be done to
determine the densities of the liquids?
5. Completely fill the cans with water. Submerge them in water and record whether they sink or float. Look up the
densities of water and aluminum in your textbook. How do these values contribute to the behavior of the cans of
beverages?
6. If materials are available, repeat Step 1 using plastic, glass, or steel containers of diet and regular soft drinks of
equal volumes. Does the composition of the container make a difference in its floating/sinking behavior?
Compare and contrast the results with those obtained for the aluminum cans.
Think About It
What factors account for the differences in density observed?
© 2013 Terrific Science
Hold the (Broken) Mayo!
Although you were probably not aware of it, emulsions are very common around a household, as evidenced by several
familiar foods and many cosmetics. Gourmet cooks and connoisseurs of fine sauces have long recognized the egg yolk as
the mark of a classy sauce; one that is smooth and rich, with lots of oil or butter “held” into the water-based mixture. The
secret of egg yolk is that it contains lecithin, a naturally-occurring emulsifying agent. Even so, the oil-holding capacity of
a sauce is limited, and when too much oil is added (such as in mayonnaise), it “breaks” into two layers.
Some substances behave similarly to emulsifying agents, but their effect is temporary. For example, solid paprika and dry
mustard help stabilize French dressing by collecting on the surfaces of the oil droplets. Honey and sugar syrup are used to
thicken some salad dressings; shaking suspends the oil droplets and their coalescing again is retarded by the viscosity of
the liquid.
Materials
Vaseline® Intensive Care® (preferred) or other hand cream
water
1/3 cup vegetable or mineral oil
several small cups or plastic glasses
teaspoon measure
cup measure
liquid dishwashing detergent
clean towel or tissues
(optional) beaten egg yolk or liquid soap
(optional) additional vegetable or mineral oil
(optional) 1 of the following emulsions:
second brand of hand cream
hair conditioner
mayonnaise
French dressing
hollandaise sauce
Safety
You may dispose of each mixture down the drain.
Exploration
1. Pour a little Vaseline Intensive Care (or other hand cream) into your palm and examine its appearance and feel.
Wipe your hands with a clean towel or tissues. Does the hand cream label provide any clues as to whether it
would be soluble in water and/or in oil?
2. Pour about 1 teaspoon Vaseline Intensive Care (or other hand cream) into a small cup or plastic glass. Add about
1/3 cup water and stir for several minutes. Use a dry finger to lightly touch the top of the liquid mixture. Record
your observation(s) of sight and touch, including a comparison to those of Step 1. Explain what has happened to
the components of the hand cream. What does this tell you about the ability of hand cream to hold water?
3. Pour about 2 teaspoons of liquid dishwashing detergent into a clean cup. Stir in about 1/2 teaspoon of the mixture
from Step 2. Continue adding a little at a time until all the mixture has been stirred in. Compare your observations
to those of Step 2 (neglect any suds). What can you say has happened to the components of the hand cream? What
chemical term describes this functioning of a liquid detergent?
4. Pour about 1 teaspoon Vaseline Intensive Care (or other hand cream) into a small cup or plastic glass. Add about
1/3 cup vegetable or mineral oil and stir for several minutes. Use a dry finger to lightly touch the top of the liquid
mixture. Record your observation(s) of sight and touch, including a comparison to those of Step 1. Explain what
has happened to the components of the hand cream. What does this tell you about the ability of hand cream to
hold oil?
5. Pour about 2 teaspoons liquid dishwashing detergent into a clean cup. Stir in about 1/2 teaspoon of the mixture from
Step 4. Continue adding a little at a time until all the mixture has been stirred in. Compare your observations to
those of Step 4 (neglect any suds). What can you say has happened to the components of the hand cream? What
chemical term describes this functioning of a liquid detergent?
6. Does the sequence of adding a broken emulsion and the dishwashing detergent make a difference? Prepare a broken
emulsion as in Step 2, then add small portions of liquid dishwashing detergent until two teaspoons have been
added.
7. (optional) Repeat Steps 4 and 5, replacing the liquid dishwashing detergent with beaten egg yolk or liquid soap.
Think About It
Why is mayonnaise classified as an emulsion? What is the cure for a “broken” emulsion and how does it work?
© 2013 Terrific Science
Italian Dressing: Can Oil and Water Mix?
You’ve probably shaken a bottle of oil-and-vinegar–type Italian salad dressing to mix it, only to have it separate again
before you pour it on your salad. Isn’t this annoying? You can investigate this system to understand why it happens as
well as to learn something about some other everyday liquids.
Materials
tape that can be written on
pen
ruler
small, clear, colorless bottle (or jar) with lid
1 of the following to half-fill the bottle:
equal amounts vegetable oil and water or vinegar
oil-and-vinegar–type Italian salad dressing (not creamy style)
liquid soap or detergent
at least 3 of the following additives:
tincture of iodine
food coloring
mineral oil
rubbing alcohol
nail polish remover
soft drink
baby oil
Safety
Since some of the additives are flammable, do not perform these activities near a heat source. You may dispose of the
final mixture down the drain and recycle the empty bottle.
Exploration
1. Place a strip of tape lengthwise on the bottle or jar, as shown in Figure 1. Half-fill the bottle or jar with either oiland-vinegar–type salad dressing or equal amounts of vegetable oil and water or vinegar. Use a pen to mark a line
on the tape at the top of each layer. Measure and record the height of each layer (the distance between the layer’s
bottom and its top). What observation(s) allows you to determine which substance constitutes the top layer and
which one the bottom? What general property of substances is responsible for this positioning? Explain.
2. Add a little more water to the bottle, then remeasure the height of each layer. How can you tell if any of the added
water dissolved in the oil? Explain your observations in terms of polarity.
3. Add just enough of one of the additives to your oil and water mixture to enable you to determine and record its
position in the bottle. Also record the height of each layer and any other significant observations about the
mixture. Gently shake the bottle and note any changes once the layers have again separated.
4. Repeat Step 3 with at least two more of the additives (added one at a time).
5. Add 20–30 drops of liquid soap or detergent to your mixture from Step 4. Shake the bottle well and allow it to stand
for several minutes. Record the height of each layer and any other significant observations about the mixture.
Explain your observations in terms of the nature of soap and detergent molecules.
Think About It
What can an oil-and-vinegar–type Italian salad dressing tell us about the polarity of some everyday liquids? Can oil and
water mix?
Layering Liquids
You probably already know that a cork floats in water because it is less dense than water. You can use this principle to
make a density column and to determine the relative densities of different objects.
Materials
clear glass bud vase or other slender glass container
tablespoon measure
liquids:
vegetable oil
dark Karo® syrup
rubbing alcohol Dawn® or other dishwashing liquid °
water (addition of 1 or 2 drops of food coloring is optional)
solids (as many as possible; must be small enough to fit in bud vase or other slender glass container):
ball bearing or BB
plastic bead
rubber stopper
cork
super ball
pine chip (part of a craft stick works)
any other solids you wish to test
Exploration
1. Place two tablespoons of one of the liquids listed above in the glass bud vase. Then add two tablespoons of one of
the other liquids. What happens? How can you tell which one has the greater density?
2. Repeat this experiment several times using different liquids from the list. The densities of the liquids are: 0.87
g/mL, 0.91 g/mL, 1.00 g/mL, 1.26 g/mL, and 1.37 g/mL. Try to match up each density with its respective liquid
based upon your results.
3. Now that you know the densities of each of the liquids, slowly pour two tablespoons of each of the liquids into the
glass bud vase in order of decreasing density (the highest density liquid on the bottom) to create a density column.
How does your density column look?
4. Drop each of the solids into the density column that you created in Step 3. What happens to each of the objects?
Explain what the position of each object in the density column means. Can you tell what the density of each
object is? Try other objects if you wish.
Think About It
What are the relative densities of various common liquids and solids?
© 2013 Terrific Science
Penny Sandwiches
From 1864 until 1983, the usual composition of a penny (its actual name is “cent”) was 95% copper and 5% zinc and tin.
Because of the increasing costs of copper, pennies are now composed of a zinc interior with a thin copper coating
comprising only 2.4% of the penny. This activity allows you to remove the inside of the penny, leaving only the thin
copper coating.
Materials
2 pennies (dated 1983 or later)
file or coarse sandpaper
2 cups lemon juice
2 cups vinegar
2 clear wide-mouthed containers (greater than 2-cup capacity)
cup measure
Safety
Do not seal the bottles. The pressure of the hydrogen gas may be sufficient to shatter the bottles.
Exploration
1. Using the file or coarse sandpaper, completely remove the copper coating from the edge of both pennies. Pour the
lemon juice into one container. Position one penny in the container so that it is standing on its edge against the
side of the container. Pour the vinegar into the second container and similarly position the second penny. Observe
the pennies for 4 or 5 minutes. What do you see? What is occurring? What is the identity of the observed
substance?
2. Observe the pennies over the course of 1 week and describe any difference(s) in their behavior. What accounts for
the difference(s)? What specific process is occurring in each container? How do you know when the processes are
complete? Write an appropriate equation representing the processes. Use your observations to rank the three
elements hydrogen, copper, and zinc from most to least reactive.
Think About It
What is the chemistry-based reason for this peculiar construction of a penny?
A Salty Separation
It can be difficult to separate a solid from a liquid. Sometimes other chemicals can be added to aid in separation. You can
imagine how difficult it would be to separate soap and water once they have been mixed. How well can you do it? Try the
following activity and see.
Materials
bar of soap (do not use detergent)
cheese or carrot grater
water
1 of the following heat sources:
stove
hot plate
microwave
heat-safe container (appropriate for use with chosen heat source)
8 clear plastic cups or glasses
2 clear plastic cups or glasses for each additional optional solid used
masking tape
marker or pen
coffee filters (fluted, basket-style filters are recommended, but any will do)
8 rubber bands
teaspoon measure
cup measure
5–7 stir sticks
table salt
sugar
optional solids (use at least one):
Epsom salt
alum (aluminum potassium sulfate—used in canning and as an astringent)
MSG (monosodium glutamate—used as a seasoning)
crushed chalk (composed of CaCO3)
Getting Ready
Grate 1/2 cup of soap using a cheese or carrot grater. Place the grated soap in the heat-safe container, add 2 cups of water,
and stir for several minutes. Heat the mixture using the stove, hot plate, or microwave, stirring occasionally until all of the
soap shavings are dissolved. It is not necessary to boil the solution. Remove the solution from the heat and allow it to cool
to room temperature.
Exploration
1. Use the masking tape and pen to label two of the empty cups “control,” two others as “table salt,” and two as
“sugar.” Pour 1/4 cup of the prepared soap-water solution into one cup of each labeled pair. Place a coffee filter in
the other cup of each labeled pair. Fold the edge of the filter over the rim of the cup and secure it with a rubber
band.
2. Add 2 teaspoons table salt to the cup of soap-water solution labeled “table salt.” Add 2 teaspoons sugar to the cup
of soap-water solution labeled “sugar.” Stir each solution for several minutes. Compare them to the control cup
with nothing added.
3. Pour each mixture into the corresponding cup with filter. Record the appearance of the filtrate that passed through
the filter. How does the material in each of the filters look and feel? What is the purpose of the control cup?
4. Predict which of the optional solids on the materials list will do a good job of separating the soap from water.
Repeat Steps 1 through 3 with at least one of the optional solids.
Think About It
What type of common compounds will separate soap from water?
© 2013 Terrific Science
Swirling and Churning Milk
Although you might think food color and soap would spread throughout milk as they do in water, they don’t. Milk’s
nonpolar fat globules have an effect on the dispersion, as the following activity will show. You might be surprised by your
results!
Materials
2 small, clear, plastic cups or glasses
water
1/4 cup whole or 2% milk
several different food colors in dropper bottles
cotton swab
dishwashing liquid
1/4 cup measure
Safety
Do not drink the milk used in this activity.
Exploration
1. Pour about 1/4 cup water into one of the cups or glasses. Add one drop each of several different food colors to the
surface of the water. What happens during the first minute? Why?
2. Pour about 1/4 cup of milk into the second cup or glass. Add one drop each of several different food colors to the
surface of the milk. What happens to the food color? Explain why the food color behaves differently in milk than
it does in water.
3. Wet one tip of the cotton swab with water and touch it to one of the food color drops in the milk. What happens to
the food color?
4. Wet the other tip of the cotton swab with dishwashing liquid. Touch it to one of the food color drops in the milk.
What happens to the food color?
Think About It
Look up the term “micelle.” Describe a micelle, and include an illustration. Then describe the nature of milk as containing
fat micelles. Explain the observation in Step 4 based on the chemical nature of soap and milk.
Tissue in a Cup: How Soggy?
Have you washed any cups or glasses recently? Have you ever tried to submerge an inverted glass, jar, or cup into water
only to have it bob back to the surface without the inside getting wet? What does this have to do with chemistry? You will
find out as you investigate several aspects of this phenomenon through this activity.
Materials
clear plastic cup or clear glass
paper cup
several tissues or paper towels
push pin or nail
2 containers large enough to completely submerge the cups (preferably with clear sides or a very large mouth to
allow observation of the sides of the cup when submerged)
ice-cold water
very hot tap water
Safety
Be cautious of the sharp point on the push pin or nail. Use appropriate procedures to avoid burning yourself with hot tap
water.
Exploration
1. Fill one container with ice-cold water. Fill the second container with very hot tap water. Submerge an inverted clear
cup or glass in the cold water for several minutes and observe from the side. Remove the cup from the cold water
and, taking care not to burn yourself, submerge the inverted cup in the hot water for several minutes and observe
as before. Repeat the submersion in cold and then hot water. Record your observations in a tabular format.
Explain any differences in your observations of the cup in cold and hot water.
2. Using any of the materials listed above, devise a way to submerge a tissue or paper towel under water without
getting it wet. Briefly outline your procedure and draw a labeled picture to illustrate what you observed. What
kept your tissue from becoming wet?
3. Make a hole in the bottom of the paper cup with the push pin or nail. Repeat Step 2 with the paper cup. Record your
observations of the water and tissues. Briefly explain your observations and draw a labeled picture to illustrate
what occurred.
Think About It
What are some properties of air in an upside-down cup submerged in water?
© 2013 Terrific Science
What’s in a Potato?
Have you ever used a 3% hydrogen peroxide solution to disinfect an open cut? If so, you probably noticed the formation
of bubbles. Although hydrogen peroxide decomposes into water and oxygen gas very slowly at room temperature, the rate
increases significantly in the presence of the enzyme catalase. Common substances containing catalase include blood,
saliva, and potatoes. Does temperature affect the functioning of catalase?
Materials
3–4 slices of fresh, raw potato or turnip
2 tablespoons 3% hydrogen peroxide solution
2–3 toothpicks or an eyedropper
sauce pan or microwave-safe container
stove, hot plate, or microwave
tablespoon measure
Getting Ready
1. Cool 1 tablespoon of 3% hydrogen peroxide in the refrigerator for several hours.
2. Boil a slice of potato or turnip until it is just slightly soft (several minutes); allow it to cool to the temperature of the
other slices.
Exploration
1. Use a toothpick or eyedropper to place several drops of room temperature 3% hydrogen peroxide solution onto a
slice of fresh, raw potato or turnip. Observe for several minutes and record your observations. Does the behavior
change with time? Write the balanced equation for the reaction.
2. Place several drops (same amount as in Step 1) of cooled 3% hydrogen peroxide onto a slice of fresh, raw potato or
turnip. Compare your observations with those from Step 1. How can any differences be explained?
3. Place several drops (same amount as in Step 1) of room temperature 3% hydrogen peroxide onto a slice of
previously-boiled potato or turnip. Compare your observations with those from Step 1. How can any differences
be explained?
4. Spit into a sink. Put several drops of hydrogen peroxide onto the saliva. What do you observe? Explain.
Challenge
How does temperature affect the ability of catalase to quicken the decomposition of hydrogen peroxide? How is the
reaction affected by a change in hydrogen peroxide temperature?