# ANNA UNIVERSITY,VI – SEMESTER, B.TECH. CHEMICAL ENGINEERING

#### CHEMICAL ENGINEERING THERMODYNAMICS – II

PART – A (10 x 2 = 20 Marks)

1. Define chemical potential. What is its physical significance?

2. What is the characteristic of an ideal solutions? State Lewis – Randall rule.

3. Give the condition of criteria for phase equilibrium.

4. Explain the maximum and minimum boiling azeotropes.

5. Name the activity coefficient – composition models of phase – equilibria. Explain Wilson equation.

6. What is the modified equation of Raoults’s Law?

7. State the standard Gibbs energy change of reaction.

8. How the equilibrium constant is related to gas phase compositions?

9. Define the coefficient of performance of a refrigerator.

10. Name the refrigeration cycles.

PART – B (5 x 16 = 80 Marks)

11.       For the binary mixture of A and B, the activity coefficients are given by

ln?1 = A                          and ln?2 = A

The vapor pressure of A and B at 353 k are 119.96 kpa and 79.97 kpa respectively. Does an azeotrope exist at 353 k? If so, what is the azeotropic pressure and composition for A = 0.6.

12.a)    Derive the Gibbs – Duhen equation for the calculation of solution properties from knowledge of the partial properties.

OR

12.b)    Define exceed properties of mixtures and obtain the equation for activity coefficient.

13.a)    The following data were reported got VLE for ethanol – water system at 298 k. Test whether the data are thermodynamically consistent.

 x1 0 0.122 0.163 0.226 0.32 0.437 0.579 0.83 1 y1 0 0.474 0.531 0.562 0.582 0.62 0.685 0.849 1 pkpa 3.17 5.57 6.02 6.38 6.74 7.02 7.3 7.78 7.86

OR

13.b)    A mixture of A and B conforms closely to Raoult’s row. The pure component vapor pressure and  in kpa are given by (t°c)

Ln  = 14.27 – ; Ln  = 14.20 –

If the bubble point of a certain mixture of A and B is at 76°C at a total pressure of 80 kpa, find the composition of then first vapor that forms.

14.a)i)  Derive the relation ?G° = – RTlnk.

ii)  What are the effects of P, T and the total strichiometric number V on the equilibrium compositions for the gas – phase reactions?

OR

14.b)    Industrial grade methanol can be produced according to the reaction.

CO(g) + 2H2 (g) ? CH3OH(g)

For this reaction ?G°400 k = -1.3484 KJ. If an equi molar mixture of CO and H2 is fed to a reactor maintained at 400 K and 1 bar, determine the fraction of CO that is converted into CH3 OH at equilibrium. Assume that the reaction mixture behaves like on ideal gas.

15.a)i)  Derive the equation for coefficient of performance of the car not refrigerator.

ii)  What are important properties of a refrigerant.

OR

15.b)    A refrigeration system requires 1 KW of power for a refrigeration rate of 3 KJ/S. Determine.

i)     the coefficient of performance

ii)     the seat rejected by the systems

iii)     the lowest temperature that the system can maintain if the heat is rejected at 308 K.