Extracting CopperOxford AQA IGCSE Chemistry: Revision notes

Copper is a relatively unreactive metal, so it can be extracted from its ores by traditional smelting. However, high-grade copper ores are becoming scarce, and copper can also be obtained from solutions of copper salts using two other methods: electrolysis and displacement with scrap iron. These methods are especially useful for extracting copper from low-grade ores or from recycled/waste sources.

Copper can be purified/obtained by electrolysing a solution of a copper salt (such as copper sulfate):

• The anode is made of impure copper, which dissolves during electrolysis: Cu → Cu²⁺ + 2e⁻
• The cathode is made of pure copper, onto which pure copper is deposited: Cu²⁺ + 2e⁻ → Cu

This produces very pure copper, which is important because impurities reduce copper's electrical conductivity — a key property for its use in wiring.

Copper can also be obtained from a solution of a copper salt by adding scrap iron. Iron is more reactive than copper, so it displaces copper from solution:

Fe + Cu²⁺ → Fe²⁺ + Cu

In this reaction:

• Iron is oxidised (loses electrons, Fe → Fe²⁺ + 2e⁻)
• Copper ions are reduced (gain electrons, Cu²⁺ + 2e⁻ → Cu)

Solid copper metal is displaced out of solution and can be collected.

Using scrap (waste) iron is a cost-effective way to extract copper because it recycles a waste material that would otherwise be discarded, while producing a useful metal (copper) from what would be a low-value or waste copper solution.