IGNOU| PHYSICAL CHEMISTRY (CHE - 04)| QUESTION PAPER – (DEC - 2022)| (B. Sc.)| ENGLISH MEDIUM
BACHELOR OF SCIENCE (B. Sc.)
Term-End Examination
December - 2022
CHE-04
PHYSICAL CHEMISTRY
Time: 2 Hours
Maximum Marks: 50
Note: Attempt all the Parts. Answer five questions
from each of the Parts A, B, C and D. Use of Log tables and Non-programmable
calculators is allowed.
Part-A
1 Each
Note: Attempt any five questions.
1. What are azeotropes?
2. What is the number of net atoms in a face centered cubic
unit cell?
3. What is the physical significance of decrease in Gibbs
free energy?
4. What will be the effect of adding 0.1 M KCl on the C. S.
T. of phenol-water system?
5. Calculate the concentration of H+ ions of a
solution whose pH is 4.
6. State Stark-Einstein's law of photochemical equivalence.
7. Give an example of a solid in a gas type of colloid.
Part-B
2 Each
Note: Attempt any five questions.
8. Deduce the dimensions of gas constant R.
9. Calculate the standard entropy change of the combustion
of methane at 298.15 K.
You can use of
the following data:
11. The molar conductance at infinite dilution for sodium
acetate, hydrochloric acid and sodium chloride are 0.009101, 0.04261 and
0.01264 Sm2 mol-1 Calculate the molar respectively.
conductance at infinite dilution for acetic acid.
12. State any two differences between a chemical reaction
and a photochemical reaction.
13. In the formation of ammonia:
N2
(g) + 3H2 (g) → 2NH3 (g)
the rate of
consumption of hydrogen at a particular instant is 4.78 × 10-4 Ms-1.
What is the rate of formation of ammonia at that instant?
14. Why does a mixture of two immiscible liquids boil at a
temperature which is lower than the boiling point of any of the pure liquids?
Part-C
3 Each
Note: Attempt any five questions.
15. Which one will have higher boiling point- ethanol or dimethyl
ether? Give reasons for your answer.
16. What is a saturated calomel electrode? Describe with the
help of a suitable diagram.
17. An ideal gas initially at temperature 3.00 × 102
K and 3.00 x 105 Pa pressure occupies 0.831 m3 volume.
Calculate the minimum amount of work required to compress the gas isothermally
and reversibly so that the final pressure is 6.00 x 106 Pa.
18. Derive the Gibbs-Helmholtz equation starting from the
equation G = H – TS.
19. When 1.00 dm3 of an aqueous solution containing
5.00 x 10-3 kg of a solute is shaken with 5.00 x 10-2 dm3
ether, it is found that 8.50 × 10-4 kg of the solute passes into
ether. How much of the solute will be left unextracted, if the same aqueous
solution is shaken with a second instalment of 5.00 x 10-2 dm3
ether? The solute exists in the same molecular state in both ether and water.
20. Discuss the static method of determining the lowering of
vapour pressure of a solvent on addition of a non-volatile solute giving a
suitable diagram.
Part-D
4 Each
Note: Attempt any five questions.
22. The solubility product of Bi (OH)3 is 4.0 ×
10-31. Calculate its solubility.
24. An orthorhombic crystal has the following parameters:
a = 8.2 × 10-10
m
b = 9.4 × 10-10
m
c = 7.5 x 10-10
m
Calculate the
distance between its (1 2 3) planes.
25. Draw and explain the phase diagram of sulphur.
26. What is fractional distillation? Describe with the help
of a suitable diagram.
27. Define most probable speed, average speed and root mean
square speed of gas molecules. Write their expression and draw a diagram for
their distribution.
28. Write the expression for Langmuir adsorption isotherm.
Also state the assumptions involved.
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