Q4 — Extraction of iron (5 marks)

Iron is extracted from iron(III) oxide in a blast furnace using carbon. Explain, using two balanced equations, how iron is produced. Identify which species is oxidised and which is reduced.

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Mark scheme (5 marks):

• Carbon burns in oxygen to form carbon dioxide: $C + O_2 \rightarrow CO_2$ (1).
• Carbon dioxide reacts with more carbon to form carbon monoxide: $CO_2 + C \rightarrow 2CO$ (1).
• Carbon monoxide reduces iron(III) oxide: $Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2$ (1) — correctly balanced.
• Iron(III) oxide is reduced (loses oxygen / iron ions gain electrons) (1).
• Carbon monoxide is oxidised (gains oxygen) — OR — carbon (in CO) acts as the reducing agent (1).

Accept the alternative direct reduction equation $2Fe_2O_3 + 3C \rightarrow 4Fe + 3CO_2$ for one of the equation marks if used in place of the CO route, but full marks require the carbon → CO₂ → CO chain to be shown.