This required practical covers Required Practical: Investigating Temperature Changes within Endothermic Reactions for GCSE Chemistry. Revise Endothermic Reactions in Energy Changes for GCSE Chemistry with 20 exam-style questions and 14 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 5 of 12 in this topic. Revise both the method and the reason for each step, because practical questions often test understanding rather than pure recall.
🧪 Required Practical: Investigating Temperature Changes
Comparing exothermic and endothermic reactions
Method:
- Measure 25 cm³ of solution into a polystyrene cup (insulated)
- Record the initial temperature
- Add the second reactant and stir with the thermometer
- Record the maximum or minimum temperature
- Calculate ΔT (temperature change)
Exothermic test:
HCl + NaOH → Temperature rises
Endothermic test:
Citric acid + NaHCO₃ → Temperature falls
Why use a polystyrene cup?
It's an insulator — reduces heat loss/gain to environment, making measurements more accurate.
Quick Check: In an endothermic reaction, what happens to the temperature of the surroundings, and why?
The temperature of the surroundings DECREASES. This is because the reaction absorbs energy from the surroundings — it takes in heat from everything around it to power the bond-breaking step. The surroundings lose thermal energy to the reaction, so they cool down.
Practice questions for Endothermic Reactions
In an endothermic reaction, energy is:
Explain why a sports cold pack becomes cold when activated.