Download LOYOLA COLLEGE (AUTONOMOUS), CHENNAI –600 034 B.Sc., DEGREE EXAMINATION - CHEMISTRY

04-11-2003
9.00 - 12.00
LOYOLA COLLEGE (AUTONOMOUS), CHENNAI –600 034
B.Sc., DEGREE EXAMINATION - CHEMISTRY
THIRD SEMESTER – NOVEMBER 2003
CH - 3500/CHE504 - PHYSICAL CHEMISRTY - I
Max:100 marks
PART - A
(10X2=20 marks)
Answer ALL questions.
1. Define Molar heat capacity at constant volume.
2. State the third law of thermodynamics.
3. Heat supplied to a Cornot engine is 1897.86 kJ. How much useful work can be done by the
engine which works between 0oC and 100oC?
4. Mention the criteria of reversibility interms of S and G.
5. For the reaction C(graphite) + 1/2 O2 (g)  CO (g) at 298k and at 1 atm pressure, H =
110.60 kJ. Calculate E.
6. Define Ebullioscopic constant of a liquid?
7. What are isotonic solutions? Give an example.
8. Mention the importance of critical Solution Temperature.
9. Express the conditions for the validity of the distribution law.
10. Determine the number of degrees of freedom for the following equilibrium at 1 atm
premure.
Water (liquid)  water (vapour).
PART - B
(8X5=40 marks)
Answer EIGHT questions.
11. Show that for an ideal gas
u
H
) T = 0.
a) ( ) T = 0. b) (
v
P
12. Internal energy and enthalpy remain constant in the isothermal expansion of an ideal gas Explain.
13. For the reaction N2 (g) + 3H2 (g)  2 NH3(g). Kp is 1.64 x 10-4 at 673 k. Calculate G
when the partial pressure of N2, H2 and NH3 are 10 atm, 30 atm and 3 atm respectively. Is
the reaction spontaneous?
14. Discuss the effect of temperature on enthalpy change of a reaction.
15. Obtain an expression for the equilibrium constant thermodynamically.
16. Explain with an example the positive deviation from Raoult's law.
17. How will you determine the molecular weight by Beckmann's method.
18. Highlight the salient features of the phase diagram of water system.
19. Derive thermodynamically the distribution law.
20. Draw and explain the phase diagram of a system having both UCST and LCST.
21. An immisible mixture of water and quinoline boils at 98.9oC under a pressure of 740 torr.
The distillate contains 77.9 g of quinoline and 1 kg of water. At the given boiling point the
vapour pressure of quinoline is 7.96 torr. Calculate the molar mass of quinoline?
22. Derive any two Maxwell's relationships.
PART - C
(4X10=40 marks)
Answer FOUR questions.
23. Obtain expressions for w, u and H for the reversible isothermal expansion of real gas.
24. a) How is Joule-Thomson coefficient calculated? Mention the importance of inversion
temperature.
(7)
o
b) Calculate the ratio of Kp to Kc at 27 C for the following equilibrium. (R = 0.082 lit
atm K-1 mol-1)
COCl2 (g)  CO(g) + Cl2(g).
(3)
25. a) Discuss the application of Lechatelier's principle to the formation of ammonia.
(6)
b) Two moles of an ideal gas undergo isothermal reversible expansion from 15 litres to 30
litres at 300 K. Calculate the work done and change in entropy.
(4)
26. a) Draw the vapour pressure - composition and boiling point - composition curves of
completely miscible binary solutions.
(5)
b) Explain the principle of steam distillation.
(5)
27. Derive phase rule equation and explain the terms involved in it with one example.
28. a) How will you determine osmotic pressure of a solution by Berkely - Hartley method? (5)
b) A 0.5% aqueous solution of kCl was found to freeze at -0.24oC. Calculate the van't
Hoff factor and the degree of dissociation of the solute at this concentration (kf = 1.86 K
kg mol-1).
(5)
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