Extraction of Metals, Oxidation & Reduction

Extraction of metals

• Unreactive metals such as gold are found in the Earth as the metal. Most metals are found as compounds, usually oxides, in ores
• A metal less reactive than carbon is extracted by heating its oxide with carbon. The carbon takes the oxygen, so the metal oxide is reduced and the carbon is oxidised: $2\text{Fe}_2\text{O}_3 + 3\text{C} \rightarrow 4\text{Fe} + 3\text{CO}_2$
• A metal more reactive than carbon must be extracted by electrolysis, which uses far more energy and costs more
• To judge an extraction process from information given, compare the reactivity of the metal with carbon, the energy needed, the cost, and any waste products