CAIE IGCSE Chemistry Electron Loss and Oxidation Number Increase

Practise identifying oxidation from electron loss or an oxidation-number increase and constructing oxidation half-equations with electrons as products.

Exam points

define oxidation as loss of electrons or an increase in oxidation number
identify the oxidised species by finding the electron donor in an ionic equation
write a balanced oxidation half-equation with the lost electrons on the right

[Maximum number: 2]

This question is about chemical reactions and electricity.

The diagram shows the apparatus used in the production of electrical energy in a simple cell.

Figure for Question 6.4.6—Oxidation in terms of: (a) loss of question 1 — CAIE IGCSE Chemistry

The zinc electrode dissolves in the electrolyte forming $\mathrm{Zn}^{2+}(\mathrm{aq})$ ions.

Write the ionic half-equation for the reaction that occurs when the zinc electrode dissolves.

$\mathrm{Zn} \rightarrow \mathrm{Zn}^{2+}+2 \mathrm{e}^{-}$

Zn as only reactant and $\mathrm{Zn}^{2+}$ as only product correct equation

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6.4.6—Oxidation in terms of: (a) loss of question 1