Problems and Solutions on Thermodynamics and Statistical Mechanics

Thermodynamics 91

or

• z(Ahi - TASi) = EAq.

If 1 mole of water forms, there must have been electric charges of 2F flowing

in the circuit, i.e., Ag = 2F. Thus the e.m.f. is

1

As given , So = 201 J/mol.K, SH = 128 J/mol K ,
SW = 66.7 J/mol.K, iZ0 = -17200 J/mol
hH = 8100 J/mol, hw = -269300 J/mol , and T = 298 K,
We have E = 1.23 V.

1093

It is found for a simple magnetic system that if the temperature T is

held constant and the magnetic field H is changed to H + AH, the entropy

S changes by an amount AS,

where C is a constant characteristic of the system. From this informa-

tion determine how the magnetization M depends on the temperature and

sketch a plot of M versus T for small H.

( wis co ns in)

Solution:

We are given that

(g) =-- CH

T2'

From dG = -SdT - MdH, we have

CH

, that is M = -.

CH

T

Thus (z) = --

H T2