Titanium is a metal used in aircraft manufacture. It cannot be extracted from its ore by reduction with carbon, and electrolysis is not used commercially for its extraction. Instead, titanium is extracted by displacement using a more reactive metal, sodium. Explain why reduction with carbon cannot be used to extract titanium, and describe how the reactivity series is used in the displacement method to extract titanium from titanium chloride using sodium.

Edexcel GCSE Chemistry (1CH0) — 4.1 Obtaining and using metals · Explain · 4 marks · View as Markdown

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

Titanium is a highly valuable metal used in the aerospace industry. Its extraction is more complex and costly than the extraction of metals such as iron or zinc.

Model answer (4 marks)

Titanium is more reactive than carbon, so carbon cannot act as a reducing agent – it would be oxidised instead of reducing the titanium compound. Reduction with carbon only works when the metal is less reactive than carbon (i.e. the metal lies below carbon in the reactivity series). Sodium is more reactive than titanium; it sits above titanium in the reactivity series and can therefore displace titanium from its chloride. In the displacement reaction, sodium metal reduces TiCl₄ to give Ti metal and NaCl: 2 Na + TiCl₄ → Ti + 2 NaCl.

Examiner tips

  • Mention that carbon cannot reduce Ti because Ti is above C in the reactivity series.
  • State that Na is above Ti, so it can displace Ti from TiCl₄.
  • Show the displacement equation to demonstrate the products.

Common mistakes

  • Confusing the positions of Ti and C in the reactivity series.
  • Failing to explain why Na can displace Ti.
  • Omitting the displacement reaction equation.

Mark scheme (4 marks)

  1. Titanium is more reactive than carbon, so carbon cannot reduce titanium compounds / carbon cannot displace titanium from its ore.
  2. Reduction with carbon only works when the metal is less reactive than carbon (i.e. carbon must be above the metal in the reactivity series).
  3. Sodium is more reactive than titanium / sodium is above titanium in the reactivity series, so sodium can displace titanium.
  4. Sodium displaces titanium from titanium chloride, producing titanium metal and sodium chloride.

Key terms in this question

reactivity series · displacement · reduction with carbon · reduction

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