A great fun demonstration of the action of a catalyst and also of an exothermic reaction.
In a measuring cylinder 100 vol hydrogen peroxide is mixed with some washing-up liquid or bubble bath and some food colouring. Then potassium iodide is dropped in. The peroxide breaks down to realese oxygen and the bubbles produce a large amount of coloured foam that comes out of the cylinder.
Elephant’s Toothpaste – Risk Assessment