Copper is an important metal used in electrical wiring. Most copper is extracted from copper-rich ores by smelting, but supplies of these ores are running out. Scientists are developing new methods to extract copper from low-grade ores. Explain why copper is a suitable metal for use in electrical wiring and describe TWO methods that can be used to extract copper from low-grade ores.

OCR A-Level Chemistry B: Salters (H433) — DM Developing metals · Explain · 5 marks · View as Markdown

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

Copper is a transition metal found in Period 4 of the periodic table. It is one of the few metals that occurs naturally in its native form, but most copper is found as copper compounds in ores. As high-grade copper ores become scarce, alternative extraction methods that use low-grade ores are increasingly important.

Model answer (5 marks)

Copper is a good conductor of electricity, so it is suitable for electrical wiring.

Phytomining: plants are grown on low‑grade ore or contaminated soil and absorb copper compounds through their roots. The plants are then harvested and burned, producing ash that contains copper compounds.

Bioleaching: bacteria convert copper compounds in low‑grade ore into a solution containing copper ions (leachate). The copper is then recovered from the solution by displacement using scrap iron or by electrolysis.

Examiner tips

  • Use the word ‘good conductor’ to get the first mark. Show the two methods in separate sentences and give the key step of copper recovery. Mention the use of scrap iron or electrolysis to obtain copper.
  • common_mistakes
  • :
  • Confusing phytomining with bioleaching; only phytomining uses plants. Forgetting to state the recovery step (displacement or electrolysis).

Mark scheme (5 marks)

  1. Copper is a good conductor of electricity (so is suitable for electrical wiring)
  2. Phytomining involves growing plants on low-grade ore / contaminated soil, which absorb copper compounds through their roots
  3. The plants are burned / harvested and burned to produce ash that contains copper compounds (bioleaching — do not credit for this point)
  4. Bioleaching uses bacteria to convert copper compounds in low-grade ore into a solution containing copper ions / leachate
  5. In both methods, copper is obtained from the solution / leachate / ash by displacement using scrap iron (or by electrolysis)

Key terms in this question

low-grade ore

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