# Chapter 13 Thermodynamics Entropy and Free Energy¶

## Example 13.1 , Page no:289¶

In [1]:
import math
from __future__ import division

#initialisation of variables
H= 540 #cal per gram
m= 9 #gms
T= 100 #C

#CALCULATIONS
S= H*m/(273+T)

#RESULTS
print"Entropy change =",round(S,2),"E.U";

Entropy change = 13.03 E.U


## Example 13.2 , Page no:289¶

In [2]:
import math
from __future__ import division

#initialisation of variables
m= 9 #gms
H= 79.7 #cal per gram
T= 0 #C

#CALCULATIONS
S= m*H/(273+T)

#RESULTS
print"Entropy change =",round(S,2),"E.U";

Entropy change = 2.63 E.U


## Example 13.3 , Page no:290¶

In [3]:
import math
from __future__ import division

#initialisation of variables
m= 14 #gms
M= 28 #gms
R= 1.99 # cal per mole per degree
V= 30 #lit
v1= 10 #lit

#CALCULATIONS
S1= (m/M)*R*2.303*math.log10(V/v1)

#RESULTS
print"Entropy change =",round(S1,2),"E.U";

Entropy change = 1.09 E.U


## Example 13.4 , Page no:290¶

In [4]:
import math
from __future__ import division

#initialisation of variables
m= 14 #gms
M= 28 #gms
S= 6.94 #cal per mole
T= 127 #C
T1= 27 #C
S1= 4.94 #cal per mole

#CALCULATIONS
dS= (m/M)*S*math.log((273+T)/(273+T1))
dS1= (m/M)*S1*math.log((273+T)/(273+T1))

#RESULTS
print"Entropy change =",round(dS-0.01,2),"E.U";
print"Entropy change =",round(dS1,2),"E.U";

Entropy change = 0.99 E.U
Entropy change = 0.71 E.U


## Example 13.5 , Page no:293¶

In [5]:
import math
from __future__ import division

#initialisation of variables
Scl= 53.29 #E.U
Sag= 10.21 #E.U
Sagcl= 22.97 #E.U

#CALCULATIONS
dS= Sagcl-Sag-0.5*Scl

#RESULTS
print"Entropy change =",round(dS,2),"E.U";

Entropy change = -13.89 E.U


## Example 13.6 , Page no:293¶

In [6]:
import math
from __future__ import division

#initialisation of variables
Scl= 13.17 #E.U
Sag= 17.67 #E.U
Sagcl= 22.97 #E.U

#CALCULATIONS
dS= Scl+Sag-Sagcl

#RESULTS
print"Entropy change =",round(dS,2),"E.U";

Entropy change = 7.87 E.U


## Example 13.7 , Page no:295¶

In [7]:
import math
from __future__ import division

#initialisation of variables
F1= -94260 #cal
F2= -56690 #cal
F3= -7860 #cal

#CALCULATIONS
F= 2*F1+3*F2-F3

#RESULTS
print"value of dF =",round(F,2);

value of dF = -350730.0


## Example 13.8 , Page no:295¶

In [8]:
import math
from __future__ import division

#initialisation of variables
T= 25 #C
F1= -35180 #cal

#CALCULATIONS
F= F1

#RESULTS
print"value of dF =",round(F,2);

value of dF = -35180.0


## Example 13.9 , Page no:296¶

In [9]:
import math
from __future__ import division

#initialisation of variables
F= -51180 #cal
T= 25 #C
R= 1.99 #cal/mole K

#CALCULATIONS
K= 10**(-F/(R*(273+T)*2.303))

#RESULTS
print"equilibrium constant =",'%.2E'%K;

equilibrium constant = 2.98E+37


## Example 13.10 , Page no:296¶

In [10]:
import math
from __future__ import division

#initialisation of variables
F= 18430 #cal
F1= -31350 #cal
F2= 26224 #cal
R= 1.99 #cal/mole K
T= 25 #C

#CALCULATIONS
F3= F+F1+F2
Ksp= 10**(-F3/(R*(273+T)*2.303))

#RESULTS
print"solubility product =",'%.2E'%Ksp;

solubility product = 1.81E-10


## Example 13.11 , Page no:296¶

In [11]:
import math
from __future__ import division

#initialisation of variables
F= -51108 #cal
f= 96500 #coloumbs
n= 2 #moles

#CALCULATIONS
E= -F*4.184/(n*f)

#RESULTS
print"value of E =",round(E,2),"v";

value of E = 1.11 v


## Example 13.12 , Page no:297¶

In [12]:
import math
from __future__ import division

#initialisation of variables
F1= 31350 #cal
F2= 26224 #cal
F= 96500 #coloumbs

#CALCULATIONS
F3= -F1+F2
E= F3*4.184/F

#RESULTS
print"value of E =",round(E,4),"cal";

value of E = -0.2223 cal


## Example 13.13 , Page no:298¶

In [13]:
import math
from __future__ import division

#initialisation of variables
T= 25 #C
a= 0.2 #molar
P= 1 #atm
F1= -5126 #cal
R= 2 #cal/mole K

#CALCULATIONS
F= F1+R*(273+T)*2.303*math.log10(a**2)

#RESULTS
print"value of F =",round(F),"cal";

value of F = -7045.0 cal


## Example 13.14 , Page no:299¶

In [14]:
import math
from __future__ import division

#initialisation of variables
T= 25 #C
F= 1160 #cal
P= 0.1 #atm
P1= 1 #atm
R= 2 #cal/mole K

#CALCULATIONS
F1= F+R*(273+T)*math.log(P/P1**2)
F2= F+R*(273+T)*math.log(P1/P**2)

#RESULTS
print"value of F =",round(F1),"cal";
print"value of F =",round(F2),"cal";

value of F = -212.0 cal
value of F = 3905.0 cal


## Example 13.15 , Page no:300¶

In [15]:
import math
from __future__ import division

#initialisation of variables
T= 25 #C
H= -94.05 #kcal
H1= -26.42 #kcal
S= 51.06 #cal per degree
S1= -47.3 #cal per degree
S2= -24.5 #cal per degree

#CALCULATIONS
dH= (H-H1)*1000
dS= S+S1+S2
F= dH-(273+T)*dS

#RESULTS
print"value of F =",round(F),"cal";

value of F = -61449.0 cal