Zinc is a metal that can be extracted from zinc oxide by heating with carbon. State the name of this type of reaction and explain why carbon can be used to extract zinc from zinc oxide.

Cambridge International IGCSE Chemistry (0620) — 9.6 Extraction of metals · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

The reaction is a reduction.

Carbon acts as a reducing agent: it removes the oxygen from zinc oxide.

Because carbon lies above zinc in the reactivity series, it is more readily oxidised.

During the reaction carbon is oxidised to CO or CO₂, leaving zinc metal.

Examiner tips

  • State the reaction type first, then give the two reasons for carbon’s effectiveness.
  • Use the terms ‘reducing agent’ and ‘reactivity series’ as they are rewarded.
  • Show the products CO/CO₂ to demonstrate oxidation of carbon.

Common mistakes

  • Calling the reaction an oxidation instead of a reduction.
  • Failing to mention the reactivity series or the oxidation of carbon.
  • Using vague phrases like ‘carbon reacts’ without specifying CO/CO₂.

Mark scheme (4 marks)

  1. The type of reaction is reduction (of the zinc oxide) / the process is called reduction
  2. Carbon removes/takes the oxygen from zinc oxide
  3. Carbon is higher/above zinc in the reactivity series
  4. Carbon (itself) is oxidised / carbon oxide (carbon dioxide or carbon monoxide) is formed as a product

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