Copper can be extracted from copper(II) oxide by heating with carbon. Explain why this method cannot be used to extract titanium from titanium(IV) oxide, and state the method that is used instead to extract titanium.

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)

Copper(II) oxide is reduced by carbon because carbon is less reactive than Cu²⁺ and can donate electrons.
Titanium(IV) oxide is not reduced by carbon because Ti⁴⁺ is more reactive than C; the reaction would give TiC and a very impure product.
Therefore a more reactive metal is required.
Titanium is extracted by reducing TiCl₄ (made from TiO₂) with a highly reactive metal such as sodium or magnesium (Kroll process).

Examiner tips

  • Use the term ‘more reactive’ to show understanding of redox potential.
  • Explain the impurity issue with TiC to justify why carbon fails.
  • Mention the conversion to TiCl₄ and the Kroll reduction step.
  • Keep the answer concise – 4 marks only.

Common mistakes

  • Saying carbon can reduce TiO₂ – ignores Ti⁴⁺’s higher reactivity.
  • Forgetting that TiCl₄ is produced before reduction.
  • Using the wrong reducing metal (e.g. aluminium) instead of sodium or magnesium.

Mark scheme (4 marks)

  1. Titanium is more reactive than carbon / carbon cannot reduce titanium(IV) oxide
  2. Titanium reacts with carbon (at high temperatures) to form titanium carbide / impure product formed
  3. Titanium is extracted by reduction using a more reactive metal (sodium or magnesium)
  4. The ore / titanium(IV) oxide is first converted to titanium(IV) chloride before reduction

Key terms in this question

titanium(IV) oxide

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