Explain why aluminium is extracted from its ore by electrolysis rather than by reduction with carbon, and why iron can be extracted by reduction with carbon.

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).

Metals are extracted from their ores by different methods depending on their position in the reactivity series.

Model answer (4 marks)

Aluminium is higher in the reactivity series than carbon, so carbon is not a strong enough reducing agent to displace aluminium from its oxide. Consequently aluminium oxide must be reduced by electrolysis. Iron lies below carbon in the reactivity series; therefore carbon can reduce iron oxide, allowing iron to be extracted by reduction with carbon.

Examiner tips

  • Use the reactivity‑series argument to justify each method
  • Mention that aluminium is more reactive than carbon, iron less reactive
  • Show the logical link: position in series → reducing power → extraction method

Common mistakes

  • Confusing the positions of aluminium and iron in the reactivity series
  • Saying carbon can reduce aluminium without explaining why it fails
  • Failing to state that electrolysis is required for aluminium

Mark scheme (4 marks)

  1. Aluminium is more reactive than carbon / aluminium is high in the reactivity series
  2. Therefore carbon cannot reduce aluminium oxide / carbon is not a strong enough reducing agent to displace aluminium
  3. Iron is less reactive than carbon / iron is below carbon in the reactivity series
  4. Therefore carbon can reduce iron oxide / carbon displaces iron from its ore

Key terms in this question

reduction · electrolysis

Related

More Extraction of metals questions

▶ Try answering this question with AI marking (free) →