A cylinder closed by a frictionless piston

PHYSICS · Multi-part · Fermi University Physics · Thermal, Statistical & Complex Systems · The laws of thermodynamics · The laws of thermodynamics

Thermal Physics, Ch The second law, entropy and irreversibility

Problem

A cylinder closed by a frictionless piston, both of negligible heat capacity, holds

1.20\,\mathrm{mol}

of nitrogen, treated as an ideal diatomic gas with constant heat capacity

C_V = \tfrac{5}{2}nR

. The piston is loaded so that the pressure of the gas stays fixed. The gas starts at

500\,\mathrm{K}

; the cylinder is put in contact with a large bath at

300\,\mathrm{K}

, whose temperature does not change, and the gas is left until it reaches

300\,\mathrm{K}

at the same pressure. ((a)) Find the entropy change of the gas. ((b)) Find the entropy change of the bath. ((c)) Find the total entropy change. ((d)) The bath is the coldest body available. Find the work lost.

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