Iron is extracted from its ore in a blast furnace using carbon. Gold, however, is found native (uncombined) in the Earth's crust and does not need to be extracted by chemical reduction. Explain why different metals require different methods of extraction.

WJEC GCSE Chemistry (Wales) — 2.3 Metals and their extraction · Explain · 4 marks · View as Markdown

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

Some metals, such as gold, are found as pure metals in the Earth's crust. Other metals, such as iron, are found as compounds in ores and must be extracted using chemical reactions. The method used to extract a metal depends on its reactivity.

Model answer (4 marks)

More reactive metals, such as iron, form stable compounds that are strongly bonded to other elements in ores. Because they readily react with oxygen and other elements, they are found as oxides or silicates and must be chemically reduced to obtain the pure metal. Less reactive metals, such as gold, do not readily react with other elements; they are therefore found in a native, uncombined state and can be collected without a reduction step. Consequently, the extraction method depends on the metal’s reactivity: highly reactive metals require energy‑intensive chemical reduction, while less reactive metals can be obtained directly from their native form.

Examiner tips

  • Use the terms 'reactive', 'native', 'chemical reduction', and 'stable compounds' as the mark scheme expects.
  • Explain the link between reactivity and the need for reduction to break strong bonds.

Common mistakes

  • Confusing the role of reactivity with the type of ore; stating that all metals are reduced.
  • Using vague phrases like 'different methods' without linking to reactivity and bond strength.

Mark scheme (4 marks)

  1. More reactive metals form stable compounds / are strongly bonded to other elements in ores
  2. Less reactive metals (such as gold) are found uncombined / as native metals because they do not readily react with other elements
  3. Metals found as compounds must be chemically reduced to obtain the pure metal / a chemical reaction is needed to break the compound apart
  4. The more reactive the metal, the more difficult / energy-intensive it is to extract it from its compound

Key terms in this question

extraction · reduction · ore

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