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. If the heat capacity of the substance is correctly represented by in equation of the
form, Cp = A + BT + CT2
Show that the error resulting when
arithmetic mean of initial and final temperature is C(T2 − T1)2/12. [16]
2. Calculate the maximum temperature in degree centigrade when the following gas
is burned with 30% excess air entering at 25 0C:
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
Determine the values of lnγ1 and lnγ2 using Margules equations. Also plot lnγ1 and
lnγ2 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/oC+230
ln P2
sat/kPa = 16.59−
3644.2
t/oC+239
Obtain the P-x, y diagram for this system at 50oC. [16]
6. Show that the residual Gibbs energy of fluids from Redlich-Kwong equation of state
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]
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