Indira Gandhi National Open University (IGNOU) 2005 B.Sc Chemistry Physical - - Question Paper
CHE-4
BACHELOR OF SCIENCE (B.Sc.) Term-End Examination December, 2005
CHEMISTRY CHE-4 : PHYSICAL CHEMISTRY
Time : 2 hours Maximum Marks : 50
Note : Attempt all the parts. Answer five questions from each of the three parts, A, B and C. From Part D, ansiwer any four questions.
9. At room temperature, among water, methyl cyanide and methanol, which is expected to have the highest surface tension ? State the reason. 2
10. Derive an expression relating hydrolysis constant of a salt of a weak acid and weak base to the dissociation constants
of the latter two. 2
11. State the criteria for spontaneity in terms of Helmholtz free energy change and Gibbs free energy change. 2
12. State the factors which affect the solubility of a gas in a liquid. State Henrys law. 2
17. At 298 K, the standard enthalpies of formation of N02 (3) and N204 (g) are 33-2 kJ mol"1 and 92 kJ mol-1. Calculate the standard enthalpy change of the following reaction : 3
N204 (g) -2 N02 (g)
18. A Carnot engine works between 3-00 x 102 K and
4 00 x 102 K. Calculate its efficiency. 3
19. Predict whether the process
CC14 (f) + H2 (g) -> HC1 (g) + CHCI3 (/)
is spontaneous at 298 K under standard state conditions.
At 298 K --9135 kJ and ArS = 41-50 J KT1
for this reaction. 3
20. Describe any one method -for the study of fast reactions. 3
21. Discuss any one method for the purification of colloidal solution. 3
22. Define the term, order of a chemical reaction. Explain any one method for the experimental determination of order of reaction. 3
23. State the meaning of the terms, fluorescence and phosphorescence. State two applications of fluorescence. 3
24. Derive van der Waals equation for a real gas. 3
25. State the principle of eqiiipartition of energy. Apply it to calculate the ratio of molar heat capacity of a diatomic gas at constant pressure to its value at constant volume at 298 K. - 5
26. (a) Discuss, with the help of examples, effect of molecular
interactions on viscosity and vapour pressure of liquids. . 3
(b) Define the term, azeotrope. State the difference between fractional distillation and azeotropic distillation. 2
27. (a) State any one method for the determination of molar
mass of a nonvolatile solute using the principle of boiling point elevation. 3
(b) Discuss powder method for the determination of
crystal structure. 2
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29. (a) Using the following data on the distribution of succinic acid between water and benzene, show that succinic acid exists as a dimer in benzene : 3 | ||||||||
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(b) Derive the relationship, C - Cv = nR
30. (a) Draw the phase diagram of sulphur and explain its
salient features. 3
(b) Discuss any one application of eutectic system. 2
CHE-4 7
Define the term, mean free path. 1
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| Earning: Approval pending. |
