Required Practical: Measuring Temperature Changes

This lesson covers the AQA GCSE Combined Science Trilogy (8464) Required Practical on investigating the variables that affect temperature changes in reacting solutions such as acid plus alkali. You need to be able to describe the method, identify variables, evaluate results, and suggest improvements.

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Purpose of the Practical

The aim is to investigate how the temperature changes when different reacting solutions are mixed. This allows you to determine whether a reaction is exothermic (temperature rises) or endothermic (temperature falls).

Typical reactions investigated:

Reaction	Type
Hydrochloric acid + sodium hydroxide (neutralisation)	Exothermic
Citric acid + sodium hydrogencarbonate	Endothermic
Dissolving ammonium nitrate in water	Endothermic
Adding a metal powder to a copper sulfate solution (displacement)	Exothermic

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Apparatus

graph TD
    A["Polystyrene Cup \n(acts as a calorimeter)"] --> B["Lid with hole \n(reduces heat loss)"]
    B --> C["Thermometer / \nTemperature Probe"]
    D["Measuring Cylinder \n(measure volumes)"] --> A
    E["Stirring Rod"] --> A