Explain why different methods are used to extract copper and aluminium from their ores, and describe one method that can be used to extract copper from low-grade copper ores.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Metals are found in ores in the Earth's crust. The method used to extract a metal depends on its position in the reactivity series. Some newer extraction methods are used when the concentration of metal in an ore is too low for traditional methods to be economical.
Model answer (4 marks)
Aluminium is more reactive than carbon, so it cannot be reduced by carbon alone; it must be extracted by electrolysis of molten alumina.
Copper is less reactive than carbon, so it can be reduced by carbon in a furnace.
For low‑grade copper ores, phytoextraction can be used: plants absorb copper from the ore.
The plants are then burnt, and the copper is recovered from the ash.
Copper is less reactive than carbon, so it can be reduced by carbon in a furnace.
For low‑grade copper ores, phytoextraction can be used: plants absorb copper from the ore.
The plants are then burnt, and the copper is recovered from the ash.
Examiner tips
- Use the exact terms ‘electrolysis’ and ‘reduction with carbon’.
- Show the reactivity relationship to justify the method.
- Mention ‘phytoextraction’ and the burning step to recover copper.
- Keep the answer to the required 4 marks – one point each.
Common mistakes
- Confusing the reactivity of aluminium and copper, or saying aluminium can be reduced by carbon.
- Forgetting to mention the burning step after phytoextraction.
- Using vague phrases like ‘chemical reaction’ instead of the specific methods.
Mark scheme (4 marks)
- Aluminium is more reactive than carbon, so electrolysis must be used to extract it.
- Copper is less reactive than carbon, so reduction with carbon can be used to extract it.
- Phytoextraction uses plants to absorb copper compounds through their roots.
- The plants are then burned and the copper compound can be removed from the ash.
Related
- All Edexcel GCSE Chemistry (1CH0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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