Elephant's Toothpaste
🐘
A fun chemistry demonstration to show the action of potassium iodide as a catalyst in the decomposition of hydrogen peroxide.
Equipment
- 50mL of 30% hydrogen peroxide solution
- Saturated potassium iodide solution
- Washing-up liquid
- Food colouring
- 500ml measuring cylinder
- Splint
Safety
For this demonstration, wear disposable gloves and safety glasses. Since oxygen is produced, do not perform this demonstration near an open flame. The solution and foam may be rinsed down the drain with water
Method
- Pour 50 mL of 30% hydrogen peroxide solution into the measuring cylinder
- Squirt in a little bit of washing up liquid and swirl it around
- Place a few drops of food colouring along the wall of the cylinder to make the foam look like toothpaste
- Add 10mL of the saturated potassium iodide solution and stand back!
- To prove that you have made oxygen touch a glowing splint to the foam and it will relight
Scientific Explanation
The hydrogen peroxide naturally decomposes very slowly to generate oxygen and water:
The potassium iodide acts as a catalyst and speed up the reaction so it appears as if elephant's toothpaste is squirting out of a tube!
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