Displacement reactions involving solutions of salts
3 marks · NormalIn the reaction below, explain which substance is the oxidising agent and which is the reducing agent. Give your reasoning in terms of electron transfer.
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Fe is the reducing agent because it loses electrons (is oxidised) and reduces Cu^{2+}. Cu^{2+} is the oxidising agent because it gains electrons (is reduced) and oxidises Fe.
Also accept: Fe gives electrons to Cu^{2+}, so Fe is the reducing agent, and Cu^{2+} is the oxidising agent.
Common mistakes: Confusing oxidising and reducing agent
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Marking points
M1 · 1 mark · Identifies Fe as the reducing agent and Cu^{2+} as the oxidising agent.
M2 · 1 mark · Describes electron loss from Fe (oxidation) and electron gain by Cu^{2+} (reduction).
A1 · 1 mark · Clearly connects agent role to electron transfer—Fe loses electrons, Cu^{2+} gains electrons.
Worked solution
Fe is the reducing agent because it gives electrons to Cu^{2+}, reducing it to Cu.
In this process, Fe is oxidised (loses electrons), and Cu^{2+} is reduced (gains electrons).
Cu^{2+} is the oxidising agent because it accepts electrons from Fe.