CAIE IGCSE Chemistry Electron Gain and Oxidation Number Decrease

Practise identifying reduction from electron gain or an oxidation-number decrease and selecting or completing reduction half-equations accurately.

Exam points

define reduction as gain of electrons or a decrease in oxidation number
identify the reduced species by finding the electron acceptor in an ionic equation
write a balanced reduction half-equation with the gained electrons on the left

[Maximum number: 1]

Iron is manufactured in a blast furnace.

The source of iron in the blast furnace is $\mathrm{Fe}_{2} \mathrm{O}_{3}$ . $\mathrm{Fe}_{2} \mathrm{O}_{3}$ is found in iron ore.

Explain how the change of oxidation number shows that iron has been reduced.

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