AQA · GCSE · Combined Science · Higher

Mass of ice produced calculation

Q02.2 3 marks

A scientist cooled the air inside a container.

Calculate the mass of ice produced.

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Marking points

1 Use consistent units and substitute energy and latent heat into $E = mL$ , for example $0.70 = m \times 330$ .
2 Rearrange to find the mass, for example $m = \frac{0.70}{330}$ .
3 Calculate the mass as $0.0021\ \mathrm{kg}$ .

Full-mark answer

$E = mL$ , so $0.70 = m \times 330$ . Therefore $m = \frac{0.70}{330} = 0.0021\ \mathrm{kg}$ .

Why this answer loses marks

$\frac{700}{330}=2.1\ \mathrm{kg}$

This converts the energy to joules but leaves the latent heat in kJ/kg, so the units are inconsistent.