Lead, carbon and gold are three substances found in the reactivity series. A student heats lead oxide with carbon in a crucible. Explain why this reaction produces lead metal, and state what type of reaction this is. Include the names of the oxidising agent and the reducing agent in your answer.

Pearson Edexcel International GCSE Chemistry (4CH1) — 2.4 Reactivity series · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Lead oxide is reduced by carbon:


i) Carbon is more reactive than lead, so it displaces lead from its oxide.


ii) Carbon removes oxygen from lead oxide, producing lead metal and CO or CO₂.


iii) The process is a redox reaction – lead is reduced and carbon is oxidised.

iv) Carbon is the reducing agent; lead oxide is the oxidising agent.

Examiner tips

  • Use the word ‘displace’ to show the reactivity difference; include the redox nature; name both agents explicitly.
  • Show the reaction equation if space allows – it demonstrates understanding of the process.

Common mistakes

  • Writing ‘lead is oxidised’ instead of ‘reduced’; confusing the roles of the agents; omitting the fact that the reaction is a redox process.

Mark scheme (4 marks)

  1. Carbon is more reactive than lead (so it can displace lead from its compound / oxide)
  2. Carbon reduces the lead oxide / carbon removes oxygen from lead oxide, producing lead metal
  3. This is a redox reaction (both oxidation and reduction occur simultaneously)
  4. Carbon is the reducing agent AND lead oxide is the oxidising agent

Key terms in this question

reactivity series · reducing agent · oxidising agent

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