LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – CHEMISTRY

WD 12

THIRD SEMESTER – April 2009

CH 3504 – THERMODYNAMICS

 

 

 

Date & Time: 05/05/2009 / 9:00 – 12:00  Dept. No.                                                   Max. : 100 Marks

 

 

 

PART – A

Answer ALL questions:                                                                                  10 x 2 = 20     

 

1. What is Joule Thomson effect?
2. What are intensive and extensive properties?
3. Define bond energy. What does a +ve value of bond energy indicate?
4. Explain heat of transition with a suitable example.
5. State second law of thermodynamics in any two ways.
6. Define thermodynamic efficiency. Explain why the efficiency of a heat engine is always less than unity.
7. State Le chatelier principle.
8. At a given temperature, the equilibrium constant K_c for the reaction is 4. If the equilibrium concentration of is 0.5 mol lit^-1, what is the equilibrium concentration of ?
9. How would the equilibrium reaction of dissociation of be affected by
10. addition of b) decreasing the volume of the container
11. What are the exceptions to the third law of thermodynamics?

 

PART – B

Answer any EIGHT questions:                                                                      8 x 5 = 40

 

11. Differentiate between reversible and irreversible processes.
12. What is an adiabatic process? Show that a constant for the reversible adiabatic expansion of an ideal gas.
13. What is Joule Thomson coefficient? Deduce the relationship between and .
14. The heat of combustion of carbon monoxide at constant volume at 27^oC is -280 KJ. Calculate its heat of combustion at constant pressure. (R=8.314 x 10^-3 KJ).
15. Derive an expression for the entropy change accompanying isothermal expansion of an ideal gas.
16. What is Gibb’s free energy? How does it vary with temperature and pressure?
17. Derive an expression for the efficiency of a carnot’s engine working between two temperatures T₁ and T₂.
18. State law of mass action. Find expressions for K_P and K_C for applying the law of mass action.

 

19. Show that .
20. Discuss the effect of change of temperature, pressure and concentration, in the contact process of manufacture of sulphuric acid.
21. The enthalpy of combustion of benzene, carbon and hydrogen are -3267.7 KJ mol^-1, -393.5 KJ mol^-1 and -286.2 KJ mol^-1 Calculate the enthalpy of formation of benzene.
22. Explain Nernst heat theorem.

 

PART – C

Answer any FOUR questions:                                                                       4 x 10 = 40

 

23. a) Discuss the variation of a reaction with temperature.
24. The heat of reaction was found to be -21.976 KJ at 27^o What will be the heat of the reaction at 50^oC? ()
25. Explain Hess law of constant heat summation and discuss its applications.
26. Derive Gibbs – Helmholtz equation and mention its application.
27. a) Derive the relationship between K_P and K_C.
28. Calculate the ratio of K_P to K_C at 27^oC for the reaction .
29. Derive Vant Hoff equation showing the variation of equilibrium constant with temperature.
30. a) State the third law of thermodynamics.
31. b) How is absolute entropy of a substance determined using third law of thermodynamics?

 

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