Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 5th Sem New 2150503 Chemical Engineering Thermodynamics Ii Previous Question Paper
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (NEW) EXAMINATION ? WINTER 2018
Subject Code:2150503 Date:16/11/2018
Subject Name: Chemical Engineering Thermodynamics-II
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) For binary azeotropic mixture deviating positively from ideality, draw vapor-liquid
equilibrium (VLE) diagrams.
03
(b) Describe phase rule and Duhem?s theorem for non-reacting system.
04
(c) Define Lewis/Randall Rule. Derive Raoult?s law. What are the limitations of
Raoult?s law?
07
Q.2 (a) With neat diagram describe the effect of increasing pressure on binary T-x1,y1 vapor-
liquid equilibrium diagram.
03
(b) Describe the phenomena of retrograde condensation.
04
(c) Assuming validity of Raoult?s law, draw P-x1,y 1 diagram for binary mixture at 75
0
C. Clearly show vapor region, liquid region, bubble point and dew point curves.
Data given:
At 75
0
C,
sat sat
12
P =83.21 kPa and P =41.98 kPa
07
OR
(c) System acetone(1)/acetonitrile(2)/nitromethane(3) at 353.15 K has the overall
composition z1 = 0.45, z2 = 0.35 and z3 = 0.20. Assuming that the Raoult?s law is
appropriate to this system, determine equilibrium pressure and vapor-liquid
composition to carry out 40% vaporization.
Date Given: The vapor pressures of the pure species at the 353.15 K are:
P1
sat
= 195.75 kPa, P2
sat
= 97.84 kPa and P3
sat
= 50.32 kPa
07
Q.3 (a) Define: (1) thermodynamic equilibrium, (2) chemical potential, and (3) fugacity
coefficient for pure species i.
03
(b) Describe graphical interpretation of following two equations relating partial molar
properties with solution properties.
12
21
11
dM dM
M =M+x and M =M-x
dx dx
04
(c) Will it be possible to prepare 0.1 m
3
of ethanol-water solution by mixing 0.03 m
3
ethanol with 0.07 m
3
pure water? If not possible, what volume should have been
mixed in order to prepare a mixture of the same strength and of required volume?
Density of ethanol and water are 789 and 997 kg/m
3
, respectively. The partial molar
volumes of ethanol and water at the desired compositions are: Ethanol = 53.6 x 10
-6
m
3
/mol; water = 18 x 10
-6
m
3
/mol.
07
OR
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (NEW) EXAMINATION ? WINTER 2018
Subject Code:2150503 Date:16/11/2018
Subject Name: Chemical Engineering Thermodynamics-II
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) For binary azeotropic mixture deviating positively from ideality, draw vapor-liquid
equilibrium (VLE) diagrams.
03
(b) Describe phase rule and Duhem?s theorem for non-reacting system.
04
(c) Define Lewis/Randall Rule. Derive Raoult?s law. What are the limitations of
Raoult?s law?
07
Q.2 (a) With neat diagram describe the effect of increasing pressure on binary T-x1,y1 vapor-
liquid equilibrium diagram.
03
(b) Describe the phenomena of retrograde condensation.
04
(c) Assuming validity of Raoult?s law, draw P-x1,y 1 diagram for binary mixture at 75
0
C. Clearly show vapor region, liquid region, bubble point and dew point curves.
Data given:
At 75
0
C,
sat sat
12
P =83.21 kPa and P =41.98 kPa
07
OR
(c) System acetone(1)/acetonitrile(2)/nitromethane(3) at 353.15 K has the overall
composition z1 = 0.45, z2 = 0.35 and z3 = 0.20. Assuming that the Raoult?s law is
appropriate to this system, determine equilibrium pressure and vapor-liquid
composition to carry out 40% vaporization.
Date Given: The vapor pressures of the pure species at the 353.15 K are:
P1
sat
= 195.75 kPa, P2
sat
= 97.84 kPa and P3
sat
= 50.32 kPa
07
Q.3 (a) Define: (1) thermodynamic equilibrium, (2) chemical potential, and (3) fugacity
coefficient for pure species i.
03
(b) Describe graphical interpretation of following two equations relating partial molar
properties with solution properties.
12
21
11
dM dM
M =M+x and M =M-x
dx dx
04
(c) Will it be possible to prepare 0.1 m
3
of ethanol-water solution by mixing 0.03 m
3
ethanol with 0.07 m
3
pure water? If not possible, what volume should have been
mixed in order to prepare a mixture of the same strength and of required volume?
Density of ethanol and water are 789 and 997 kg/m
3
, respectively. The partial molar
volumes of ethanol and water at the desired compositions are: Ethanol = 53.6 x 10
-6
m
3
/mol; water = 18 x 10
-6
m
3
/mol.
07
OR
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2
Q.3 (a) For ideal gases, prove that the partial molar volume is identical with the pure-species
volume at the mixture T and P.
ig ig
ii
VV ?
03
(b) For binary mixture derive following equations to calculate fugacity coefficient from
virial equation of state.
? ?
2
1 11 2 12
P
? ln ? = B + y ?
RT
04
(c) Derive an expression for the fugacity coefficient of a gas obeying the equation of
state P(V-b)=R T and estimate the fugacity of ammonia at 10 bar and 298 K, given
that b = 3.707 x 10
-5
m
3
/mol.
07
Q.4 (a) Liquids A and B form an azeotrope containing 46.1 mole percent A at 101.3 kPa and
345 K. At 345 K, the vapor pressure of A is 84.8 kPa and that of B is 78.2 kPa.
Calculate the van Laar constants.
03
(b) Explain any one method for testing consistency of VLE data.
04
(c) Describe Wilson and NRTL equations with their applications and limitations.
OR
07
Q.4 (a) Describe Poynting correction.
03
(b) Discuss the effect of temperature, pressure and liquid phase composition on relative
volatility of binary mixture following modified Raoult?s law.
04
(c)
The activity coefficients in a binary system are given by
22
1 2 2 1
ln ? = A x a n d l n ? = A x .
Show that if the system forms an azoetrope, then azeotropic composition is given by
sat
az 2
1 sat
1
P 11
x 1 ln
2 A P
??
??
??
?? ??
??
??
.
07
Q.5 (a) Describe effect of temperature on reaction equilibrium constant.
03
(b) Develop expressions for the mole fractions of reacting species as functions of the
reaction coordinate for:
(1) A system initially containing 2 mol NH3 and 5 mol O2 and undergoes the
reaction:
3 2 2
4 ( ) 5 ( ) 4 ( ) 6 ( ) NH g O g NO g H O g ? ? ?
(2) A system initially containing 3 mol H2S and 5 mol O2 and undergoing the
reaction:
2 2 2 2
2 ( ) 3 ( ) 2 ( ) 2 ( ) H S g O g HO g SO g ? ? ?
04
(c) Explain block diagram for dew point pressure calculation.
OR
07
Q.5 (a) If G
E
/RT = A x1 x2 for a liquid phase, show by stability analysis that LLE is predicted
for A ? 2.
03
(b) Briefly describe constant pressure liquid/liquid solubility diagrams.
04
(c) Explain the method of Lagrange?s undetermined multipliers for gas phase reaction
to minimize total Gibbs free energy.
07
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This post was last modified on 20 February 2020