Problems and Solutions on Thermodynamics and Statistical Mechanics

Thermodynamics 71

component, chemical systems of constant mass. U is the internal energy
and S is the entropy of the system.

( wis co nsin)

Solution:
(a) The classical ideal gas.

This requires a < 0, i.e., the system has a negative coefficient of expansion

at const ant pressure.

= 0. This requires C, = 00. The system has two

T

P CP

coexistent phases.

(d) ( g)T = (g) = 0. This requires ,d = ; - (g)v = 0.

V

It is a system whose coefficient of pressure at constaht volume is zero.

(e) All systems of a single component and constant mass satisfy this

Maxwell relation.

1074

Consider an ideal gas whose entropy is given by

"I n

U

n

u+5Rln-++Rln- ,

where n = number of moles, R = universal gas constant, U = internal

energy, V = volume, and u = constant.

(a) Calculate cp and cv, the specific heats at constant pressure and

volume.