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AQA · GCSE · Combined Science · Higher

Temperature-pressure graph relationship

Q04.3 1 mark

A student investigated how the pressure of a gas depends on its temperature. The volume of the gas did not change.

Sketch graph with pressure in MPa on the vertical axis and temperature in °C on the horizontal axis. The graph is a straight line sloping upwards from a positive pressure value when temperature is zero.

Figure 7

Enlarged question image

Sketch graph with pressure in MPa on the vertical axis and temperature in °C on the horizontal axis. The graph is a straight line sloping upwards from a positive pressure value when temperature is zero.
Figure 7

Figure 7 shows a sketch graph of the results.

The student said that as the temperature increases the pressure increases.

Give a better description of the relationship between temperature and pressure.

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Marking points

  1. 1 Describe the relationship as linear, or as having a constant gradient.

Full-mark answer

The relationship between temperature and pressure is linear.

Why this answer loses marks

Pressure is directly proportional to temperature.

The mark scheme does not accept directly proportional because the sketch line does not pass through the origin.

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