How impure copper can purified using electrolysisWatch
Copper is less reactive than carbon, so it can be extracted from its ores by heating it with carbon. For example, copper is formed if copper oxide is heated strongly with charcoal, which is mostly carbon:
copper(II) oxide + carbon → copper + carbon dioxide
2CuO + C → 2Cu + CO2
Removing oxygen from a substance is called reduction. The copper oxide is reduced to copper in the reaction above.
Copper is purified by electrolysis. Electricity is passed through solutions containing copper compounds, such as copper(II) sulphate. Pure copper forms on the negative electrode.