The gas laws
3 marks · NormalA car tyre contains air at a pressure of 230 kPa at 15°C. After a drive, its temperature rises to 40°C. Assume the volume stays constant.
Calculate the final pressure in the tyre. Give your answer to 2 significant figures.
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250 kPa (±2)
Also accept: 249 kPa
Common mistakes: Not converting Celsius to Kelvin; Using wrong formula
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Marking points
M1 · 1 mark · Converts both temperatures to Kelvin (288 K and 313 K).
M2 · 1 mark · Uses and correctly substitutes values.
A1 · 1 mark · Evaluates to 250 kPa (2 s.f.), with correct unit. (follow-through)
Worked solution
Convert temperatures: 15°C = 288 K, 40°C = 313 K.