"Why does hydrogen peroxide foam when you put it on a cut?."

Hydrogen peroxide (H2O2) is something you can buy at the drug store. What you are buying is a 3-percent solution, meaning the bottle contains 97-percent water and 3-percent hydrogen peroxide. Most people use it as an antiseptic. It turns out that it is not very good as an antiseptic, but it is not bad for washing cuts and scrapes and the foaming looks cool.

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