CAIE IGCSE Chemistry 6.4.13 Oxidising Agents and Reducing Agents Questions

Identify electron acceptors and donors in redox equations, and justify oxidising or reducing-agent roles using oxidation numbers and observations.

Exam points

identify the oxidising agent as the electron acceptor that is itself reduced
identify the reducing agent as the electron donor that is itself oxidised
use ionic equations and oxidation numbers to justify each choice
use reagent colour changes as supporting evidence for oxidising or reducing behaviour

[Maximum number: 1]

The equation for the reaction of sulfur dioxide with acidified potassium dichromate(VI) is shown.

3 \mathrm{SO}_{2}+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+2 \mathrm{H}^{+} \rightarrow 3 \mathrm{SO}_{4}^{2-}+2 \mathrm{Cr}^{3+}+\mathrm{H}_{2} \mathrm{O}

What is oxidised and what is the oxidising agent?

oxidised

oxidising agent

$\mathrm{SO}_{2}$

$\mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{2-}$

$\mathrm{SO}_{2}$

$\mathrm{H}^{+}$

$\mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{2-}$

$\mathrm{H}^{+}$

$\mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{2-}$

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