A frictionless

PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics

Problem

A frictionless, thermally insulated piston confines a sample of argon gas in a vertical cylinder open to the atmosphere. The gas has a mass of

2.40\,\text{g}

and is initially in equilibrium with the surroundings at a temperature of

300\,\text{K}

and an absolute pressure of

1.25\,\text{atm}

. The atomic mass of argon is

40.0\,\text{g\,mol}^{-1}

. Assume the gas behaves ideally. The ideal-gas constant is

R=0.0821\,\text{L\,atm\,mol}^{-1}\text{K}^{-1}

and the Boltzmann constant is

k_B=1.38\times10^{-23}\,\text{J\,K}^{-1}

. (a) Determine the total number of argon atoms in the cylinder. (b) Calculate the initial volume occupied by the gas. (c) A second cylinder of identical construction contains the same mass of neon gas at the same temperature and external pressure. Without performing additional numerical calculations, state whether the volume of the neon sample is less than, equal to, or greater than the volume found in part (b). Justify your answer qualitatively in terms of microscopic particle count.

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