Elephant Toothpaste
Teacher’s Instructions
Teaching objectives:
 Students will observe several examples of chemical and
physical reactions
 Students will carry out the decomposition reaction of
hydrogen peroxide
 Students will describe and illustrate the changes of
the hydrogen peroxide chemical reaction
Recommended Grades: K-5
Estimated Time: about an hour
Key concepts and terms:
Reaction: a transformation or change
Chemical Reaction: a process in which one substance is
converted into a new substance with new properties
Physical Reaction: a process in which a substance changes
in size, shape or color but does not change in composition.
Catalyst: A substance that alters the speed of a chemical
reaction
Procedure:
1. Over all tables, drape trash can bags to try and
prevent excess mess. At each student’s seat, place a
cake pan or plastic bin, an empty soda bottle with its
cap, a closed container with ½ cup hydrogen peroxide,
a container with 1 tsp dry active yeast, and a spoon.
At each table set out a container of food coloring.
2. Ask the class to give examples of reactions. Tell them
baking a cake is a kind of reaction, and so is blowing
out a candle. Give examples of both a chemical and a
physical reaction. If you want, play the Chemical vs.
Physical Game (See Supplementary Exercises).
3. Tell the class that they will be working with a
chemical called Hydrogen Peroxide, or H2O2. This is a
fairly non-toxic chemical, but they should be wearing
goggles. Show them a picture of the molecule, and how
it breaks down with very slowly into water and oxygen.
Katy Harmon
January 2008
4. Ask the class what would happen if the hydrogen
peroxide turned into water and oxygen VERY fast. Tell
them that a reaction helper called a catalyst can help
a reaction speed up.
5. If there is room in the class, hand out the worksheet.
6. Tell everyone to carefully open the hydrogen peroxide
container. Using a funnel, have the students carefully
pour the liquid into the bottles. After pouring, tell
the students to put caps back on their bottles.
7. Tell students they can choose a color food dye to put
in their bottles. Let them carefully squeeze 4-5 drops
into the bottle if they want to. Help them add one
squirt of Dawn dish detergent, and then have them put
the caps back on their bottles.
8. Heat up the water. Plan on bringing extra, because
some may evaporate. The water doesn’t have to boil,
but it should be just warm enough to dissolve yeast
(and not hot enough to burn anyone!)
9. Distribute ~10 mls (2 tsp) of water to each student in
their yeast container. Tell them to stir the yeast
with the spoons until it looks smooth and not lumpy.
If students need something to do, have them gently
swirl their bottle. Tell them not to shake it (the
reaction won’t work well if they do). Wait until
everyone is ready.
10.
Explain to the class what everyone is going to
do. Tell them not to do anything until you say ‘Go!’.
Tell the students they will uncap their bottles, pour
the brown solution (the helper or catalyst) into their
bottles, and wait. Tell them they can touch the bottle
and articulate their observations (the reaction is
exothermic, so the bottle should feel warm.) If there
is a sink and plenty of paper towels in the room, tell
them they can touch the foam gently. Ask everyone if
they understand what they are going to do. If you feel
confident they are ready and you are ready, say
“Ready? Go!”
11.
Ask students to talk about what they see as it’s
happening. What does the foam feel like? Is there
anything left in the bottle?
12.
Get students to participate in clean up
activities, then have an assistant continue to clean
up while you move students to new tables or to a sitdown area on the floor.
Katy Harmon
January 2008
13.
Time permitting, have students draw a sketch of
the “Elephant Toothpaste.” Ask them what they thought
happened. Do they think it was a chemical or a
physical reaction? Hand out the Elephant Toothpaste
recipes so they can try the experiment at home with
their families.
Why it works:
Hydrogen peroxide is an oxidizing agent. Over time, it is
converted to water and oxygen in a decomposition reaction
according to the following formula:
2 H2O2 --> 2 H2O + O2
However, this reaction goes very slowly. It is, however,
favorable, and is
exothermic: it releases some heat as it takes place.
Reactions can speed up by
adding heat, adding more reaction materials, or adding a
catalyst. In the case of
the Elephant’s Toothpaste, the yeast is a catalyst which
makes the hydrogen
peroxide release the oxygen faster. The reaction is
exothermic, meaning that heat is released as the reaction
proceeds. The detergent is added as a surfactant: it allows
the catalytic yeast to react with as much of the hydrogen
peroxide as
possible.
Supplementary exercises
Chemical vs. Physical Game: Make up some cards ahead of
time that depict chemical or physical changes. Show each
card to the class and ask them to guess if the change is
chemical or physical.
Physical reaction: Bring in some snow from outside, or ice
from a freezer. How did the water change? What color is
snow? What color is water? Freezing and melting are
examples of physical reactions.
Chemical reaction: Take an empty bottle and add vinegar to
it (about a cup). Wrap about 2 tbsp. of baking soda loosely
in aluminum foil, stick it in the bottle, and put the cork
in. Keep the bottle pointing upward, and shake vigorously.
Kapow! This is an example of a chemical reaction.
Katy Harmon
January 2008
REFERENCES:
1.
Elephant’s Toothpaste – Kid Friendly. Online:
<http://www.stevespanglerscience.com/experiment/elephants-toothpaste>
Elephant Toothpaste
Materials List

20-30 empty plastic soda bottles, 24 oz. or smaller,
with caps

3% Hydrogen peroxide: 120 mls (about ½ cup) per child

Dawn ultra concentrated dishwashing detergent (works
the best, though others can be substituted)

Sealable containers to hold hydrogen peroxide
Katy Harmon
January 2008

Containers to hold yeast mixture

Yeast: 1 tsp per child

Water: 2 tsp per child

Plastic spoons

Plastic funnels

Heating device for water (microwave, hot plate,
electric kettle)

20-30 Cake pans or large plastic bins

Food coloring

Glitter

Garbage bags

Goggles for children

Age-appropriate worksheets (below)
Elephant Toothpaste
Recipe
You can make elephant toothpaste at home!
You will need:



3% Hydrogen Peroxide
An empty soda bottle with a cap (16 oz. or smaller)
Dawn dishwashing detergent
Katy Harmon
January 2008








A large cake pan
Yeast
Warm water (not boiling)
Food coloring
Smock or lab coat
Goggles
An adult
A place it’s okay to make a mess!
Procedure
1. First, put on your smock or lab coat and goggles.
Always be careful when doing chemistry, even in
the kitchen.
2. Set the empty soda bottle inside the cake pan.
3. Have an adult help you get ½ cup of the hydrogen
peroxide and pour it into the empty soda bottle.
4. Add 4-5 drops of food coloring and one squirt of
the dishwashing detergent. Cap the bottle
tightly.
5. Don’t shake the bottle, but swirl it around
gently so that the ingredients can mix.
6. Mix 1 tsp of yeast with 2 tsp hot water until it
dissolves and there are no more lumps.
7. Uncap the soda bottle and quickly pour in the
yeast mixture. Yikes! The bottle will be warm
from the reaction, and the foam is safe to touch
(it’s just oxygen bubbles and soap).
8. Clean up! Make sure you wash your hands well
before your next activity.
Name_______________
Date________________
What did you observe when the reaction
happened?
…………………………………………………………………………………………………………..
…………………………………………………………………………………………………………..
Katy Harmon
January 2008
Draw a picture below of what you saw in your
bottle:
Elephant Toothpaste
Recipe
Thrill your friends…scare your siblings…try making
elephant toothpaste at home!
You will need:





3% Hydrogen Peroxide
An empty soda bottle with a cap (16 oz. or smaller)
Dawn dishwashing detergent
A large cake pan
Yeast
Katy Harmon
January 2008





Warm water (not boiling)
Food coloring
Smock or lab coat
Goggles
A place it’s okay to make a mess
Procedure
1. First, put on your smock or lab coat and goggles.
Always be careful when doing chemistry.
2. Set the empty soda bottle inside the cake pan.
3. Get ½ cup of the hydrogen peroxide and pour it
into the empty soda bottle. This is toxic stuff,
so don’t fool around with it too much.
4. Add 4-5 drops of food coloring and one squirt of
the dishwashing detergent. Cap the bottle
tightly.
5. Don’t shake the bottle, but swirl it around
gently so that the ingredients can mix.
6. Mix 1 tsp of yeast with 2 tsp hot water until it
dissolves and there are no more lumps.
7. Uncap the soda bottle and quickly pour in the
yeast mixture. The bottle will be warm from the
reaction, and the foam is safe to touch (it’s
just oxygen bubbles and soap).
Name_______________
Date________________
Elephant Toothpaste
What did you observe when the reaction happened?
…………………………………………………………………………………………………………..
…………………………………………………………………………………………………………..
Katy Harmon
January 2008
Which ingredient caused the decomposition of H2O2 to
go faster?
…………………………………………………………………………………………………………..
How else could you make your reaction go
faster?
…………………………………………………………………………………………………………..
…………………………………………………………………………………………………………..
…………………………………………………………………………………………………………..
Was this a chemical or physical reaction? (circle
one)
CHEMICAL
PHYSICAL
Name___________________
Date____________________
Elephant Toothpaste:
Worksheet 1
There’s a lot of chemistry vocabulary we’ll be going over today. Fill out this
worksheet and bring it to Katy or Liz at the end. If everything’s correct,
they’ll have a small prize for you. Good Luck!
1. A chemical reaction is….
………………………………………………………………………………………………
………………………………………………………………………………………………
Katy Harmon
January 2008
2. Draw or describe an example of a chemical reaction
below:
3. A physical reaction is….
………………………………………………………………………………………………
………………………………………………………………………………………………
4. Draw or describe an example of a physical reaction:
1
5. True or False:
____ Acids react with bases
____Vinegar is a base
____ Alka-seltzer reacts with acetic acid
____An acid-base reaction is a chemical reaction
6. Which one of these clues could prove a scientific
experiment involves a chemical reaction? (circle at least
one)
Bill Nye does the experiment
change
You smell a gas that is released
You see a color
Your teacher tells you
it’s a chemical reaction
Katy Harmon
January 2008
7. How could you speed up a reaction? List just one way.
………………………………………………………………………………………………
………………………………………………………………………………………………
8. What catalyst did we use in the Elephant Toothpaste
demonstration?
………………………………………………………………………………………………
………………………………………………………………………………………………
9. (Extra Credit) Why is chemistry so awesome?
………………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
2
Katy Harmon
January 2008