Oxidising Agents — Past Paper Practice
15 Questions · Sections A–C · Definitions, Electron Transfer & Oxidation Numbers
Definitions
5 QuestionsDefine the term oxidising agent.
[2 marks]What is the difference between an oxidising agent and an oxidant?
[1 mark]State what happens to an oxidising agent in terms of oxidation state during a redox reaction.
[1 mark]Give two examples of common oxidising agents used in the laboratory.
[2 marks]In the reaction between magnesium and oxygen: 2Mg(s) + O₂(g) → 2MgO(s), identify the oxidising agent and explain why.
[2 marks]Electron Transfer
5 QuestionsIn terms of electrons, what does an oxidising agent do during a chemical reaction?
[1 mark]In the half-equation: Cl₂ + 2e⁻ → 2Cl⁻, is chlorine acting as an oxidising or reducing agent? Justify your answer.
[2 marks]In the reaction: Fe³⁺(aq) + e⁻ → Fe²⁺(aq), what role is Fe³⁺ playing and what is happening to it in terms of electron transfer?
[2 marks]Explain why oxygen is described as a strong oxidising agent in terms of its electron behaviour.
[2 marks]In the ionic equation: MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O, identify the species being reduced and state what role it plays in a redox reaction.
[2 marks]Oxidation Numbers
5 QuestionsWhat happens to the oxidation number of an oxidising agent during a redox reaction?
[1 mark]In the reaction: 2Fe³⁺ + Sn²⁺ → 2Fe²⁺ + Sn⁴⁺, identify the oxidising agent and show the change in oxidation number.
[2 marks]In the reaction: Cr₂O₇²⁻ + 14H⁺ + 6e⁻ → 2Cr³⁺ + 7H₂O, determine the oxidation state of chromium in Cr₂O₇²⁻ and in Cr³⁺, and explain what this shows about the role of Cr₂O₇²⁻.
[3 marks]Hydrogen peroxide (H₂O₂) can act as either an oxidising agent or a reducing agent. When it acts as an oxidising agent, what is the change in oxidation number of oxygen, and what product forms?
[2 marks]In the displacement reaction: Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s), identify the oxidising agent, state the change in its oxidation number, and write the ionic half-equation for the reduction step.
[3 marks]⚡ Quick Reference: The OIL RIG Rule
OIL
Oxidation Is Loss
Loses electrons → oxidation number INCREASES → REDUCING agent
RIG
Reduction Is Gain
Gains electrons → oxidation number DECREASES → OXIDISING agent
Common Oxidising Agents (Cambridge Favourites):
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