# Chapter 12:Thermodynamics¶

## Ex12.1:pg-413¶

In [1]:
  import math   #Example 12_1

#To find the work done by the gas
d1=800           #Units in meter**3
d2=500           #Units in meter**3
p1=5*10**5       #Units in Pa
w1=p1*(d1-d2)*10**-6      #Units in J
p2=2*10**5       #Units in Pa
d3=200*10**-6        #Units in meter**3
p3=3*10**5         #Units in Pa
w2=(p2*d3)+(0.5*p3*d3)        #Units in J
print "The work done by the gas is=",round(-(w1+w2))," J"

The work done by the gas is= -220.0  J


## Ex12.2:pg-415¶

In [2]:
  import math   #Example 12_2

#To estimate the Cv of nitric acid
r=8314        #Units in J/Kmol K
m=30        #Units in Kg/Kmol
Cv=2.5*(r/m)         #Units in J/Kg K
print "The estimated Cv value of nitric acid is Cv=",round(Cv)," J/Kg K"
#in textbook the answer is printed wrong as Cv=690 J/Kg K correct answer is 692 J/Kg K

The estimated Cv value of nitric acid is Cv= 693.0  J/Kg K


## Ex12.3:pg-415¶

In [3]:
  import math   #Example 12_3

#To find the final temperature
t1=t1+273   #Units in K
gama=1.4     #Units in Constant
p1=1        #units in Pa
v1_v2=15      #Units of in ratio
logT2=math.log10(t1)-((gama-1)*(math.log10(p1)-math.log10(v1_v2)))
T2=10**logT2                #Uniys in K
print "The final temperature is T2=",round(T2)," K"

The final temperature is T2= 886.0  K


## Ex12.4:pg-417¶

In [4]:
  import math   #Example 12_4

#To describe the Temperature changes of the gas
print "This type of process is termed as throttling process and described by the equation Delta U=- Delta W\n"
print "Where Delta W is the work done"

This type of process is termed as throttling process and described by the equation Delta U=- Delta W

Where Delta W is the work done


## Ex12.5:pg-418¶

In [5]:
  import math   #Example 12_5

#To findout by how much the entropy of the system changes
m=20         #Units in gm
alpha=80      #Units in cal/gm
t=4.184                 #Units in J/Cal
Q=m*alpha*t        #Units in J
T=273        #Units in K
S=Q/T          #Units in J/K
print "The entropy is Delta S=",round(S,1)," J/K"

The entropy is Delta S= 24.5  J/K


## Ex12.6:pg-419¶

In [6]:
  import math   #Example 12_6

#To findout how much electricity is needed
Tc=278           #Units in K
Th=293         #Units in K
COP=Tc/(Th-Tc)            #Units in ratio
Qc=210000            #Units in J
W=Qc/COP                     #Units in J
print "The amount of Electricity is required is Delta W=",round(W)," J"

The amount of Electricity is required is Delta W= 11666.0  J