Problems and Solutions on Thermodynamics and Statistical Mechanics

(Ann) #1
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
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