Metals can be refined by using electrolysis. Copper can be purified in this way. The electrolytic cell, shown inFigure 1,使用纯金属制成的阴极和阳极ade of impure copper metal. The electrolyte used is copper sulfate. The impurities fall to the bottom of the cell.

The reduction reaction at the negative cathode is: Cu²⁺+ 2e^-→ Cu.In this reaction, copper cations gain electrons to become elemental copper.

The oxidation reaction at the positive anode is: Cu → Cu²⁺+ 2e^-.In this reaction, copper loses two electrons to become a copper cation.

Figure 1 - Refinement of copper using electrolysis.