Elephant's Toothpaste

Does your elephant friend have stinky breath? Unfortunately, this experiment won’t help his breath smell any better…but you will have fun making a giant tube of foam that looks like it could be an elephant’s toothpaste!

Australian Curriculum links

  • Science > Chemical Sciences > Year 2 > ACSSU031
  • Science > Chemical Sciences > Year 5 > ACSSU077
  • Science > Chemical Sciences > Year 6 > ACSSU095
  • Science > Chemical Sciences > Year 8 > ACSSU225
  • Science > Chemical Sciences > Year 9 > ACSSU179

You'll need

  • Dishwashing gloves
  • Safety glasses
  • 100 mL, 6% Hydrogen Peroxide (available from most chemists)
  • Measuring cup
  • 500 mL PET bottle
  • Funnel
  • Plastic tray or large baking dish
  • Dishwashing detergent
  • Food colouring (any type except cochineal)
  • Small cup
  • Sachet of dry yeast
  • Tablespoon
  • Lukewarm water
  • Optional pop-top for extra height

Try this

Safety: This experiment requires adult supervision. All participants should wear dishwashing gloves and safety glasses as standard chemical handling practice.

  1. Put on the safety glasses and gloves.
  2. Measure 100 mL of the 6% hydrogen peroxide using the measuring cup.
  3. Place the funnel in the PET bottle.
  4. Pour the hydrogen peroxide into the PET bottle via the funnel.
  5. Remove the funnel and place the PET bottle on the plastic tray or baking dish.
  6. Add a large squirt of dishwashing detergent to the PET bottle.
  7. Add a squirt of food colouring.
  8. In the small cup, empty a sachet of dry yeast and add four tablespoons of lukewarm water. Mix well.
  9. Place the funnel in the PET bottle.
  10. Quickly add the yeast mixture to the PET bottle via the funnel.
  11. Quickly remove the funnel, stand back and watch what happens.

Further investigation

Try making the elephant toothpaste in different sized PET bottles or in containers with different shaped openings to determine how these affect the stream of foam. Try using different quantities of the mixtures to determine how it affects the amount of foam.

What's happening?

The foam is made as the dishwashing detergent traps tiny oxygen bubbles created by the chemical reaction that is happening inside the bottle. The thick foam oozes out of the top of the bottle and looks like toothpaste when toothpaste is being squeezed out of its tube. The activity is called ’Elephant’s Toothpaste’ because the large stream of foam looks like toothpaste that is big enough for an elephant!

Hydrogen peroxide is a molecule made up of hydrogen atoms and oxygen atoms. It can be expressed using the chemical formula, 2H2O2. Under the right conditions, hydrogen peroxide will undergo a chemical reaction to break down into two parts, oxygen and water.

We can write out this decomposition reaction as a chemical equation:

hydrogen peroxide --› water + oxygen

2H2O2 --› 2H2O + O2

When a chemical that is made up of only one molecule breaks down into two different, smaller molecules, it’s called a decomposition reaction. This particular decomposition reaction is also an ’exothermic’ reaction, meaning it gives off heat. If you feel the sides of the bottle, the plastic should feel quite warm.

Yeast contains an enzyme called catalase. The enzyme is called catalase because it works as a ’catalyst’ in this reaction. A catalyst is a substance that speeds up the rate of a chemical reaction without changing its products. The yeast is added to the hydrogen peroxide to speed up the reaction. The catalase in the yeast speeds up the process of breaking down the hydrogen peroxide and thus produces oxygen and water more quickly. The oxygen gets trapped by the dishwashing detergent as many tiny bubbles.

Real world links

Hydrogen peroxide is commonly found in hair colouring products. Hydrogen peroxide bleaches the natural pigments in human hair by breaking down hair’s melanin, the tiny grains of pigment which create natural hair colour.

Our bodies naturally synthesise both hydrogen peroxide and catalase (the same enzyme found in yeast that helps to breakdown hydrogen peroxide). However, as we get older our bodies continue to produce hydrogen peroxide, but make less catalase. Because there is less catalase available to breakdown the hydrogen peroxide the concentration of hydrogen peroxide in our bodies increases. The increased concentration of hydrogen peroxide breaks down the melanin in our hair and causes our hair to lose its colour and turn grey or white.