A student investigates the reactivity of three metals — silver, aluminium and iron — by adding each one to a solution of copper(II) sulfate. Explain which metals will displace copper from copper(II) sulfate solution, and describe what the student would observe when each of those metals is placed in the solution.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
The reactivity series, in order from most reactive to least reactive, includes: aluminium, iron, copper, silver.
Model answer (4 marks)
Aluminium and iron are above copper in the reactivity series, so they will displace copper from CuSO₄.
• When aluminium is added, a reddish‑brown solid of copper deposits on the aluminium surface and the blue CuSO₄ solution fades.
• When iron is added, a similar reddish‑brown copper deposit forms on the iron and the blue solution also fades.
Silver is below copper in the series and will not displace it; no reaction occurs.
• When aluminium is added, a reddish‑brown solid of copper deposits on the aluminium surface and the blue CuSO₄ solution fades.
• When iron is added, a similar reddish‑brown copper deposit forms on the iron and the blue solution also fades.
Silver is below copper in the series and will not displace it; no reaction occurs.
Examiner tips
- State the reactivity order first, then link each metal to its position relative to copper. Use the phrase ‘displace copper’ and describe the colour change and solid deposit. Mention that silver does not react.
- common_mistakes
- :
- Writing that silver reacts with CuSO₄. Forgetting to describe the colour change of the solution. Using vague terms like ‘react’ instead of ‘displace copper’.
Mark scheme (4 marks)
- Silver does not displace copper because silver is less reactive than copper (accept: silver is below copper in the reactivity series)
- Aluminium and iron displace copper because they are more reactive than copper (accept: they are above copper in the reactivity series)
- A reddish-brown / pink solid (copper) forms / deposits on the surface of the aluminium or iron
- The blue colour of the copper(II) sulfate solution fades / becomes less intense (accept: the solution becomes colourless)
Related
- All Pearson Edexcel International GCSE Chemistry (4CH1) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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