What You Need
- 1/2 cup of 20- volume 6% hydrogen peroxide liquid (available from pharmacies)
- 1 tablespoon of dry yeast
- washing up liquid
- 3 tablespoons f warm water
- food colouring (optional)
- a small cup
What To Do
- This will make a mess, so do it outside or on a washable surface
- Put some safety goggles on and carefully pour the hydrogen peroxide into the bottle
- Add some food colouring if you would like your toothpaste a fun colour
- Add 1 tablespoon of washing up liquid and swirl it about a bit
- In the small cup, mix the warm water and the yeast and mix for around 30 seconds
- Pour the yeast mixture into the plastic bottle, stand back and watch the uncontrollable foaminess commence
The Science Bit
The yeast acts as a catalyst (something which helps speed up the reaction) to remove the oxygen from the hydrogen peroxide. Because this is done very fast, loads and loads of little bubbles are created. The foam is just soap, water and oxygen so you can have a play with it before just pouring it down the plughole.
The reaction is an exothermic reaction - meaning it creates heat, so you may have noticed the bottle getting warm.
The reaction is an exothermic reaction - meaning it creates heat, so you may have noticed the bottle getting warm.