Core Practical: Investigating Electrolysis of Aqueous Solutions

This lesson covers the Core Practical for investigating the electrolysis of aqueous solutions as required by the Edexcel GCSE Combined Science specification (1SC0). You need to understand the practical setup, how to identify gases produced at each electrode, how to record results systematically, and how to explain the products formed.

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Aim

To investigate the electrolysis of a range of aqueous solutions and identify the products formed at each electrode.

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Background

When an aqueous solution of an ionic compound is electrolysed, there are four types of ion present:

1. Positive ions from the dissolved compound (e.g. Cu²⁺, Na⁺)
2. Negative ions from the dissolved compound (e.g. Cl⁻, SO₄²⁻)
3. H⁺ ions from the partial dissociation of water
4. OH⁻ ions from the partial dissociation of water

The products at each electrode depend on the reactivity of the ions and on the rules for predicting products.

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Apparatus