Boyle's law

2 marks · Normal

State Boyle's law in terms of the relationship between the pressure and volume of a fixed mass of gas at constant temperature.

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For a fixed mass of gas at constant temperature, the pressure is inversely proportional to the volume.

Also accept: pV = constant for a fixed mass of gas at constant temperature

Common mistakes: Saying pressure is directly proportional to volume.

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Marking points

B1 · 1 mark · States that pressure and volume are inversely proportional (or pV = constant).

B1 · 1 mark · States or implies 'for a fixed mass at constant temperature'.

Worked solution

At constant temperature, Boyle's law states that the pressure of a fixed mass of gas is inversely proportional to its volume. This means that if the volume increases, the pressure decreases, provided the temperature is unchanged. Mathematically, pV = constant for a fixed mass of gas at constant temperature.