Neutralisation Reactions and Salts

This lesson covers neutralisation reactions and the formation of salts as required by the AQA GCSE Combined Science Trilogy specification (8464). You must be able to write word and balanced symbol equations, predict the products of neutralisation reactions, and understand the ionic equation for neutralisation.

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What Is Neutralisation?

Neutralisation is the reaction between an acid and a base to form a salt and water. During neutralisation, the pH moves towards 7.

General Equation

$\text{acid} + \text{base} \rightarrow \text{salt} + \text{water}$acid+base→salt+water

The Ionic Equation for Neutralisation

Every acid–base neutralisation involves the same essential ionic change:

$\text{H}^+(aq) + \text{OH}^-(aq) \rightarrow \text{H}_2\text{O}(l)$H+(aq)+OH−(aq)→H2​O(l)

The H⁺ ions from the acid combine with the OH⁻ ions from the base to form water.

Exam Tip: If you are asked to write an ionic equation for any neutralisation reaction, the answer is always: H⁺(aq) + OH⁻(aq) → H₂O(l). This equation applies regardless of which specific acid and base are used.

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Acid + Metal Oxide → Salt + Water

When an acid reacts with a metal oxide (an insoluble base), the products are a salt and water.