Chemical engineering thermo dynamics Ii Jntu Model Paper{Www.Studentyogi.Com}

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Code No: R05310803
Set No. 1
III B.Tech I Semester Regular Examinations, November 2007
CHEMICAL ENGINEERING THERMODYNAMICS-II
(Chemical Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks

1. (a) The latent heat of vaporization of ethyl alcohol is experimentally to be 200
cal/gm. at its normal BP of 78 0C. Its critical temperature is 243 oC. Estimate
the heat of vaporization at a temperature of 180 oC.

(b) De ne of heat of solution based on one mole of solution and one mole of solute.
Also derive the relationship between them. [6+10]

2. The gas stream from a sulphur burner is composed of 45 mol % SO2, and 55 mol%
O2. This gas stream at 1 bar and 480 oC enters a catalytic converter when SO2
is further oxidized to SO3. Assuming that the reaction reaches equilibrium, deter-
mine how much heat must be removed from the converter to maintain isothermal
conditions per 100 mol of entering gas Cp / R = A + BT +D/T2 [16]

A 103 B 10-5 D Hf, 25oC Gof, 25oC
J/mol J/mol
SO2 5.699 0.801 -1.015 -296830 -300194
O2 3.639 0.506 -0.227 - - - - - - - - - -
SO3 8.060 1.056 -2.028 -395720 -371060

3. (a) Discuss the determination of fugacity from equation of state, with special
reference to Vander waals gas and show that, ln f = ln (RT/(V-b)) + b/(V-b)
? 2a/RTV.
(b) Show mathematically that the entropy change on mixing is not zero even for
ideal gases. [12+4]

4. (a) Elucidate the vapor-liquid equilibrium of binary systems with the help of p-x-y
and t-x-y diagrams.
(b) Write and explain models for excess Gibbs energy based on the local compo-
sition. [12+4]

5. (a) Discuss the phase rule and Duhem’s theorem for non-reacting system, explain
in detail.
(b) The binary system of benzene (1) / ethyl benzene (2) conforms closely to
Raoult’s law. Vapor pressures for the pure species are given by the following
Antoine equations:
ln 1 sat = 13 8594 - 2773.78
t/0 C+220.07
ln 2 sat = 14 0045 - 3279.47
t/0 C+213.2


Code No: R05310803
Set No. 1
6. Determine expressions for GR, HR, SR implied by the vander waals equation of
state. [16]

7. Develop equations that apply to the limiting case of binary LLE for which the
-phase is very dilute in spices 1 and the -phase is very dilute in species2. [16]

8. A mixture of N2, H2 and Argon in the mole ratio 1:3:2 enters a catalytic reactor
for the synthesis of ammonia. The reactor is maintained at 400oC and 20 Mpa.
Estimate the degree of conversion (K = 1096*104). [16]


Code No: R05310803
Set No. 2

1. If the heat capacity of the substance is correctly represented by in equation of the
form, p = + + 2
Show that the error resulting when p H is assumed = p evaluated at the
arithmetic mean of initial and nal temperature is ( 2 - 1)2 12. [16]

2. Calculate the maximum temperature in degree centigrade when the following gas
is burned with 30% excess air entering at 25 0 :

CO 30%
H2 15%
CO2 5%
N2 50%

The mean heat capacities of these gages (in cal/ g mole 0K) are:

CO : 7.587
H2 : 7.138
O2 : 7.941
N2 : 7.507
CO2 :11.92
H2O : 9.39

Heat of combustion data: Hc (k cal/ g mole) CO = 67.63 and H2O = 68.32. [16]

3. Derive the relation for the calculation of Gibbs free energy of ideal gas mixture,
starting from fundamental property relation. [16]

4. Vapor-liquid equilibrium data for the system 1, 2 dichloro methane (1) /methanol
(2) at 50 oC are as follows:

P/kpa x1 y1
55.55 0.000 0.000
58.79 0.042 0.093
64.59 0.189 0.265
65.76 0.349 0.349
65.59 0.415 0.367
63.86 0.632 0.418
59.03 0.835 0.484
48.41 0.945 0.620
31.10 1.000 1.000


Code No: R05310803
Set No. 2
Determine the values of ln 1 and ln 2 using Margules equations. Also plot ln 1 and
ln 2 Vs x1. [16].

5. The excess Gibbs energy for a binary system is given by: GE / RT = 0.45 X1 X2.
The pure component vapor pressures are given by:
ln P1 sat kPa = 14 39- 2795.8
t/o C+230
ln P2 sat kPa = 16 59- 3644.2
Obtain the P-x, y diagram forC+239 system at 50oC.
t/o
this [16]

6. Show that the residual Gibbs energy of uids from Redlich-Kwong equation of state
bRT 1 .5 ln (1 + ).
[16]
is GR = - 1 - ln(1 - ) - a
RT
7. Name the di erent types of binary mixtures in terms of solubility. What are the
thecritical solution temperature and the three phase temperature for a partially
miscible liquid solution. Show them on diagram. [16]

8. Write short notes on:

(a) E ect of temperature on equilibrium constant K
(b) Law of mass action.
[8+8]


Code No: R05310803
Set No. 3

1. Water and a liquid mixture of propane and butane are admitted into a vaporizer at
50 oC and leave as vapors at 175 oC. The hourly 25 kg water, 350 kg propane and
550 kg of butane are admitted. Estimate the heat requirement in the vaporizer.

Component Latent heat of vaporization Boiling point a b×103 C×106
cal/gm mole at 100o temp Tc o
Propane 5038 96.6 8.41 35.95 -6.97
Butane 6138 151.8 2.25 45.40 -8.83
Water 10388 96.6 7.14 2.64 0.046
Cp =a+bT+cT2 where Cp is in cal/mol.k and T is in K. Mention the assumption
made to solve the problem. [16]

2. Carbon monoxide gas is burned at constant pressure with 100% excess air. The
reactants enter at 25 0C and the exhaust gases leave the reaction chamber at 1200
0C Estimate the heat loss from the reaction chamber
Standard heat of combustion of CO=-282,900 J/mol
Cp =a+bT+cT2 Cp in J/mol-K, T in K
The constants of a, b, c are:
[16]

a b×103 c×106
CO2 26.75 42.26 -14.25
N2 27.02 5.81 -0.29
2 25.29 13.25 -4.20

3. (a) Derive an expression for estimating fugacity of a liquid at a given T and P.
(b) The partial molar volume of methanol in methanol- water. Solution at x1 =
0.3881 (mole fraction) is 39.176 × 10 -6 m3/mol. The density of the mixture
is 905.376 kg/m3. Calculate the partial molar volume of water in the solution.
[8+8]

4. Derive and discuss the Wilson equation as a model of solution behaviour for mul-
ticomponent system. Discuss the merits of this model over others. Explain its
temperature dependence also. [16]

5. (a) Explain bubble print and dewprint.
(b) Describe the vapor/ liquid equilibrium calculation procedure for DEW P. Va-
por and liquid phases may be considered as non- ideal. [6+10]


Code No: R05310803
Set No. 3
6. When the compressibility factor Z is a function of P, T show that the residual
dB
entropy of uids from virial equation of state is SR R = -P dT . [16]
R
7. Discuss about LLE and draw its solubility diagrams represented in the form of an
‘island’ [16]

8. In a laboratory investigation, acetylene is catalytically hydrogenated to ethylene at
1,1200C And 1 bar. If the feed is an equimolar mixture of acetylene and hydrogen,
what is the composition of the product stream at equilibrium? The reactions are
22 2+2 [16]
K1= 4x105, K2 =2.5x10-6.
2+22 24


Code No: R05310803
Set No. 4

1. Water and a liquid mixture of propane and butane are admitted into a vaporizer at
50 oC and leave as vapors at 175 oC. The hourly 25 kg water, 350 kg propane and
550 kg of butane are admitted. Estimate the heat requirement in the vaporizer.

Component Latent heat of vaporization Boiling point a b×103 C×106
cal/gm mole at 100o temp Tc o
Propane 5038 96.6 8.41 35.95 -6.97
Butane 6138 151.8 2.25 45.40 -8.83
Water 10388 96.6 7.14 2.64 0.046
Cp =a+bT+cT2 where Cp is in cal/mol.k and T is in K. Mention the assumption
made to solve the problem. [16]

2. (a) 40 kg of ethyl alcohol and 50 kg of acetic acid are charged into a reactor to
yield ethyl acetate as per the reaction,
C2H5OH (l) + CH3COOH (l) = C2H5OOCCH3 + H2O
The reaction is 60% complete. Estimate the heat e ect of this process heat of
combustion in cal/mol: C2H5OH = -326700; CH3COOH = - 208300; C2H5OOCCH3

= - 538760, H2O( )= - 68.3 Kcal/gm mole.
(b) Write short notes on e ect of temperate on heat of reaction. [10+6]

3. (a) Estimate Z, HR and SR at 70 oC and 200Kpa for an equimolar vapor mixture
of propane and pentane using virial expansions B11 = -276, B22 = -809, B12
= -466 cm3/mol.
(b) Write and explain fundamental residual property relation. [10+6]

4. For Diethyl ether (1) - Chloroform (2) at 30 oC, a1 = 0.71 and a2 = 0.57, P1sat =
sat = 86.59 kPa. The system is believed to governed by Margules
33.73 kPa and P2
type of equations for activity coe cients. Prepare a p-x-y diagram for the system
at 30 oC. [16]

5. (a) Explain bubble print and dewprint.
(b) Describe the vapor/ liquid equilibrium calculation procedure for DEW P. Va-
por and liquid phases may be considered as non- ideal. [6+10]

6. Show that the residual Gibbs energy of uids from Redlich-Kwong equation of state
is GR = - 1 - ln(1 - ) - a bRT 1 .5 ln (1 + ). [16]
RT
7. Discuss about liquid-liquid Equilibrium (LLE). Draw liquid-liquid solubility dia-


Code No: R05310803
Set No. 4
8. For the gas phase reaction CO2 (g) + 2H2 (g) CH3OH (g) at 10000 C and at
500 bar pressure,calculate the equilibrium composition using the following data:
K = 0.68 at 10000C; The fugacity coe cients at this pressure:
CO2 =0.99; H2 = 1.15; CO = 1.08; H2O = 0.86. [16]

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Chemical engineering thermo dynamics Ii Jntu Model Paper{Www.Studentyogi.Com}