Sodium, calcium, zinc, iron and copper can all be placed in the reactivity series. Explain how displacement reactions can be used to determine the order of reactivity of two metals.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A student has two metals, metal X and metal Y, and solutions of their salts. They want to find out which metal is more reactive.
Model answer (4 marks)
1. A more reactive metal can displace a less reactive metal from its compound.
2. Put metal X into a solution of a salt of metal Y, and also put metal Y into a solution of a salt of metal X.
3. Observe whether a reaction occurs – a reaction or a deposit of the new metal shows that the added metal is more reactive.
4. If metal X displaces metal Y but metal Y does not displace metal X, then metal X is more reactive than metal Y.
2. Put metal X into a solution of a salt of metal Y, and also put metal Y into a solution of a salt of metal X.
3. Observe whether a reaction occurs – a reaction or a deposit of the new metal shows that the added metal is more reactive.
4. If metal X displaces metal Y but metal Y does not displace metal X, then metal X is more reactive than metal Y.
Examiner tips
- Use the phrase ‘displaces’ to show understanding of displacement reactions.
- Show both directions of the experiment to prove the order.
- Explain that a reaction indicates the added metal is higher in the reactivity series.
Common mistakes
- Confusing ‘reactive’ with ‘corrosion’ or ‘solubility’.
- Not mentioning both directions of the experiment.
- Assuming a reaction always occurs without checking the reverse reaction.
Mark scheme (4 marks)
- A more reactive metal displaces a less reactive metal from its compound / solution
- Place metal X into a solution of a salt of metal Y (and vice versa / repeat with metal Y in a solution of a salt of metal X)
- Observe whether a reaction occurs — a reaction / deposit of new metal forming shows that the added metal is more reactive
- If metal X displaces metal Y from its salt solution but metal Y does NOT displace metal X from its salt solution, then metal X is more reactive than metal Y
Key terms in this question
displacement · reactivity series
Related
- All AQA GCSE Chemistry (8462) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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