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A level: Kinetic Theory Questions

Q16.

(a) The concept of an absolute zero of temperature may be explained by reference to the behaviour of a gas. Discuss one experiment that can be performed using a gas which would enable you to explain absolute zero and determine its value.

It is not necessary to give full details of the apparatus.

Your answer should:

include the quantities that are kept constant

identify the measurements to be taken

explain how the results may be used to find absolute zero

justify why the value obtained is absolute zero.

[6 marks]

(b)

(i) State two assumptions about the movement of molecules that are used when deriving the equation of state, pV = – 1/3 N m (crms)2 for an ideal gas.

[2 marks]

(ii) Three molecules move at the speeds shown in the table below:

molecule
speed / m s–1
1
2000
2
3000
3
7000

Calculate their mean square speed.

[3 marks]

(c) The average molecular kinetic energy of an ideal gas is 6.6 × 10–21 J.

Calculate the temperature of the gas.

[3 marks]

(14 marks total)