Absolute zero
3 marks · NormalA physics classroom is at 18 °C. A scientist is cooling a gas sample to investigate pressure at lower temperatures.
Convert the classroom temperature to kelvin.
The gas is cooled to 5 °C. What is this temperature in kelvin?
If the gas were cooled to 0 K, what would happen to the motion of the particles? Explain.
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(a) 291 K
(b) 278 K
(c) Particles would stop moving, as all kinetic energy is lost at absolute zero.
Common mistakes: Omitting +273 in conversions.
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Marking points
B1 (a) · 1 mark · Correct Kelvin conversion: 18 + 273 = 291 K.
B1 (b) · 1 mark · Correct Kelvin conversion: 5 + 273 = 278 K.
B1 (c) · 1 mark · States that particle motion stops or is minimal at 0 K.
Worked solution
a) T(K) = 18 + 273 = 291 K
b) T(K) = 5 + 273 = 278 K
c) At 0 K (absolute zero), particles have no kinetic energy and their motion stops.