What You Need:
- Empty plastic bottle - 50ml
- Hydrogen peroxide solution (available at any chemist) - 3%
- Packet of active yeast (available at any grocery store)
- Liquid dishwashing detergent
- Warm water
- Food colouring
- Ask a parent to help you with this step. Pour 1/2 cup hydrogen peroxide solution, 1/4 cup dishwashing soap and a few drops of food colouring into the bottle. Swish the bottle around to mix the ingredients.
- Set the bottle in a sink or some other place where you won't mind getting wet foam flowing all over.
- In a separate container, mix a packet of active yeast with a little warm water. Give the yeast about 5 minutes to activate before proceeding to the next step.
- When you are ready, pour the yeast mixture into the bottle.
Hydrogen peroxide is a reactive molecule that readily decomposes into water and oxygen. In this demonstration, yeast catalyses the decomposition so that it takes place much more rapidly than normal. The dish-washing detergent captures the oxygen that is released, making foam. Food colouring adds colour to the bubbles that are formed. This is an easy experiment that shows decomposition, reaction aided by a catalyst and an exothermic (heat producing) reaction.