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Thermal physics (A-level only)

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Question 27

A mixture of neon atoms and krypton atoms is contained in a cylinder of volume VVV enclosed by a piston. The gas mixture is in thermal equilibrium at a temperature of 340 K340\text{ K}340 K.

1.

State the relationship between the mean kinetic energies of the neon atoms and the krypton atoms in this mixture.

[1]
2.

Calculate the root mean square speed (crmsc_{\text{rms}}crms​) of the neon atoms.

  • Molar mass of neon = 2.0×10−2 kg mol−12.0 \times 10^{-2}\text{ kg mol}^{-1}2.0×10−2 kg mol−1
  • Universal gas constant R=8.31 J mol−1 K−1R = 8.31\text{ J mol}^{-1}\text{ K}^{-1}R=8.31 J mol−1 K−1
  • Avogadro constant NA=6.02×1023 mol−1N_{\text{A}} = 6.02 \times 10^{23}\text{ mol}^{-1}NA​=6.02×1023 mol−1
  • Boltzmann constant kB=1.38×10−23 J K−1k_{\text{B}} = 1.38 \times 10^{-23}\text{ J K}^{-1}kB​=1.38×10−23 J K−1
[3]
3.

Explain, in terms of the kinetic theory model, how reducing the temperature of the gas mixture decreases the pressure it exerts on the piston.

[4]

Thermal physics (A-level only) Questions

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