To carry that experiment you need:
- high buret
- 30% hydrogen peroxide (perhydrol)
- solid potassium or sodium iodide ( KI or NaI)
- soap powder
Pour perhydrol into the buret (about 1/5 of its height), then pour the soap powder -
about 1 teaspoonful. Mix the soap with the liquid.
After that add 1/2 of teaspoonful of solid potassium iodide. Be carefull because foam appears very quickly and it could make some brown stain - it contains iodine I2 .
3H2O2 + KI = 3H2O + KIO + O2
2KIO + H2O2 = I2 + 2KOH + O2
Oxygen causes a lot of foam if soap is mixed with perhydrol before adding KI.