Chapter 7 : The second law of thermodynamics

Example 7.1 Page No : 137

In [1]:
# Variables
T1 = 308 			#K
T2 = 373. 			#K
T3 = 538. 			#K

# Calculations
e1 = (T2-T1)/T2
e2 = (T3-T1)/T3

# Results
print  'Efficiency  = %.3f '%(e1)
print  ' Efficiency  = %.3f '%(e2)

Efficiency  = 0.174 
 Efficiency  = 0.428

Example 7.2 Page No : 139

In [2]:
# Variables
T = 25  			#C
T1 = 0. 			#C
h = 79.8 			#cal g**-1
j = 4.18*10**7 			#ergs

# Calculations
Wc = (T-T1)*h/(273+T1)
W = (T-T1)*h*j/(273+T1)

# Results
print  'Work required  = %.1f cal'%(Wc)
print  ' Work required  = %.2e ergs'%(W)

Work required  = 7.3 cal
 Work required  = 3.05e+08 ergs

Example 7.3 Page No : 151

In [3]:
# Variables
import math 
R = 1.98 			#cal			#mol K
x = 0.75
n = 9

# Calculations
dS = -R*(n*(x/n)*math.log(x/n)+(1-x)*math.log(1-x))

# Results
print  'Entropy  = %.2f cal deg**-1 mole**-1'%(dS)

Entropy  = 4.38 cal deg**-1 mole**-1
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