Electrolysis.

Electrolysis involves both Oxidation and Reduction.

You can use electrolysis to purifying metals, for example Copper, the cathode is the where you want the place to be purified – oxidation, and the anode is the impure lump of metal - reduction, the electrolyte must contain a solution of the metal for example Copper Sulphate. The sludge of impurities is left at the bottom of the electrolyte.

Electrolysis can also to be used to plate metals, the anode is the pure metal and…