Simon Roy, age 14, of Orleans, Ontario, Canada, for his question:

WHAT IS ELECTROLYSIS?

A process in which an electric current is passed through a liquid, causing a chemical reaction to take place, is called electrolysis.

When using water, electrolysis breaks up the water into two separate gases: hydrogen and oxygen. If the liquid is a solution that includes a metal, electrolysis breaks up the solution so that the metal is removed.

The electrolysis of metallic solutions is useful in putting metal coatings on objects, and in refining or purifying metals.

Magnesium and aluminum are produced commercially by electrolysis. Copper and other minerals can be purified by electrolysis.