Question Constellation Sign up for free AQA · GCSE · Chemistry · Higher
Thermal insulation in calorimetry
A student investigated the energy change of the reaction between zinc and copper sulfate solution.
- Measure 25 cm³ of copper sulfate solution into a polystyrene cup.
- Measure the temperature of the copper sulfate solution.
- Add 0.20 g of zinc powder to the copper sulfate solution.
- Stir the reaction mixture.
- Record the highest temperature reached.
- Repeat steps 1 to 5 with different masses of zinc powder.
Explain why using a polystyrene cup gives more accurate results than using a glass beaker.
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Marking points
- 1 Compares polystyrene with glass as the better thermal insulator.
- 2 Links the insulation to less energy transfer/loss to the surroundings.
Full-mark answer
Polystyrene is a better thermal insulator than glass, so less energy is transferred from the reaction mixture to the surroundings and the measured temperature change is closer to the true value.
Why this answer loses marks
Polystyrene gives a bigger temperature change.
State the insulation comparison and connect it to reduced energy transfer, not just the reading.