This how it works covers Measuring Temperature Change in the Lab within Exothermic Reactions for GCSE Chemistry. Revise Exothermic Reactions in Energy Changes for GCSE Chemistry with 20 exam-style questions and 14 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 5 of 12 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
⚙️ Measuring Temperature Change in the Lab
You can measure energy change using a polystyrene cup calorimeter:
- Measure initial temperature of solution(s)
- Mix the reactants in an insulated container (polystyrene cup)
- Stir and record the maximum temperature reached
- Calculate temperature change (ΔT = final - initial)
If temperature increases → exothermic
If temperature decreases → endothermic
A polystyrene cup is used because it is a thermal insulator — it reduces heat loss to the environment, giving a more accurate measurement of the temperature change due to the reaction alone.
Quick Check: In an exothermic reaction, is the energy of the products higher or lower than the energy of the reactants?
The energy of the products is LOWER than the energy of the reactants. The difference in energy is released to the surroundings as heat, causing the temperature to rise. On an energy profile diagram, the products line sits below the reactants line.
Practice questions for Exothermic Reactions
In an exothermic reaction, energy is transferred:
Explain, in terms of bond breaking and bond making, why combustion is an exothermic reaction.