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 dierent 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) Eect of temperature on equilibrium constant K

(b) Law of mass action. [8+8]

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