Learning objective

Identify oxidising and reducing agents from oxidation-state changes.

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Topic

Oxidation, reduction and redox equations

Subtopic

Oxidation states

AQA A Level ChemistryPhysical chemistry

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Understand this objective

Short explanation

To identify oxidising and reducing agents from oxidation-state changes, first, understand that an oxidising agent is reduced, meaning it gains electrons and decreases in oxidation state, while a reducing agent is oxidised, meaning it loses electrons and increases in oxidation state. For example, in the reaction of zinc with copper(II) sulfate, zinc is oxidised from 0 to +2, acting as the reducing agent, while copper(II) is reduced from +2 to 0, acting as the oxidising agent. By tracking these changes in oxidation states, one can effectively identify the agents involved in redox reactions.

Key concepts

oxidising agentreducing agent

Why it matters

This objective helps connect Oxidation states to exam-style questions, flashcards, and revision notes for Oxidation, reduction and redox equations.

Common mistakes

1 linked

Identifying Oxidising and Reducing Agents: To correctly identify oxidising and reducing agents, remember that an oxidising agent is reduced (gains electrons, decreases in oxidation state), while a reducing agent is oxidised (loses electrons, increases in oxidation state). For example, in the reaction where Fe^2+ is oxidised to Fe^3+ and MnO4^- is reduced to Mn^2+, Fe^2+ is the reducing agent and MnO4^- is the oxidising agent. Assign oxidation states to each species before and after the reaction to clarify their roles.

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