12 Chemistry Impq CH02 Solutions 01
12 Chemistry Impq CH02 Solutions 01
12 Chemistry Impq CH02 Solutions 01
SOLUTIONS
VSA QUESTIONS (1 - MARK QUESTIONS)
1.
2.
Which type of solid solution will result by mixing two solid components with
large difference in the sizes of their molecules?
3.
4.
5.
6.
7.
8.
9.
10.
M M
Ans. : 2 , 10
*12. N2 and O2 gases have KH values 76.48 kbar and 34.86 kbar respectively
at 293 K temperature. Which one of these will have more solubility in
water?
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*13. Under what condition molality and molarity of a solution are identical.
Explain with suitable reason.
*14. Addition of HgI2 to KI (aq.) shows decrease in vapour pressure. Why?
15.
What will happen to the boiling point of the solution formed on mixing two
miscible liquids showing negative deviation from Raoults law?
16.
Liquid Y has higher vapour pressure than liquid X, which of them will
have higher boiling point?
17.
18.
19.
20.
21.
22.
If kf for water is 1.86 K kg mol1, what is the freezing point of 0.1 molal
solution of a substance which undergoes no dissociation or association of
solute?
[Hint : Tf = iKf . m]
24.
*25. What is the maximum value of vant Hoff factor (i) for Na2SO4 . 10H2O?
[Ans. : i = 3]
26.
What is the value of vant Hoff factor (i) if solute molecules undergo
dimerisation.
[Ans. : i = 0.5]
27.
*28. The Phase Diagram for pure solvent and the solution containing nonvolatile
solute are recorded below. The quantity indicated by X in the figure is
known as :
[Ans. : Tb]
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*29. AgNO3 on reaction with NaCl in aqueous solution gives white precipitate.
If the two solutions are separated by a semi-permeable membrane, will
there be appearance of a white ppt. in the side X due to osmosis?
2.
(b)
(b)
3.
4.
5.
Draw the total vapour pressure vs. mol fraction diagram for a binary
solution exhibiting non-ideal behaviour with negative deviation.
6.
The vapour pressure curve for three solutions having the same nonvolatile solute in the same solvent are shown. The curves are parallel to
each other and do not intersect. What is the correct order of the
concentrations of the solutions.
[Hint. : A < B < C]
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1 bar
7.
8.
9.
*10. When 1 mole of NaCl is added to 1 litre water, the boiling point increases?
When 1 mole of CH3OH is added to 1 litre water, the boiling point
decreases? Suggest reasons.
11.
*12. 1 gram each of two solutes A and B (molar mass of A > molar mass of
B) are dissolved separately in 100 g each of the same solvent. Which
solute will show greater elevation in boiling point and Why?
Solution
2 - MARK QUESTIONS
13.
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(a)
(b) Name the phenomenon involved in this experiment so that the level
of liquid in this the funnel has risen after some time.
14.
(a)
(b)
2.
(c)
3.
4.
(b)
(c)
5.
6.
RBC swell up and finally burst when placed in 0.1% NaCl solution.
(b)
When fruits and vegetables that have been dried are placed in
water, they slowly swell and return to original form.
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(c)
*7.
Glycerine, ethylene glycol and methanol are sold at the same price per
kg. Which would be cheaper for preparing an antifreeze solution for the
radiator of an automobile?
[Ans. : Methanol]
*8.
9.
(a)
10% glucose (p1), 10% urea (p2), 10% sucrose (p3) [Osmotic
pressure]
(b)
(c)
[Elevation in b.pt.]
[Depression in f.pt.]
100
Mb = 9.5 g mol1
p A p A 25
18
=
p A
95
100
760 pA
25
18
=
pA = 724 mm of Hg]
760
95
100
10.
(a)
(b)
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2.
(a)
(b)
3.
4.
(a)
(b)
(c)
Calculate the amount of ice that will separate out on cooling solution
containing 50 g of ethylene glycol in 200 g H2O to 9.3C. (Kf for
water = 1.86 K kg mol1)
[Ans. : 38.71g]
(a)
(b)
(c)
NUMERICAL PROBLEMS
1.
2.
3.
M1 V1 + M2 V2
V1 + V2
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5.
6.
The solubility of oxygen in water is 1.35 103 mol L1 at 20C and 1 atm
pressure. Calculate the concentration of oxygen at 20C and 0.2 atm
pressure.
[Ans. : 2.7 104 mol L1]
7.
Two liquids X and Y on mixing form an ideal solution. The vapour pressure
of the solution containing 2 mol of X and 1 mol of Y is 550 mm Hg. But
when 4 mol of X and 1 mole of Y are mixed, the vapour pressure of
solution thus formed is 560 mm Hg. What will be the vapour pressure of
pure X and pure Y at this temperature?
[Ans. : X = 600 mm Hg; Y = 400 mm Hg]
8.
9.
10.
11.
Calculate the amount of NaCl which must added to one kg of water so that
the freezing point is depressed by 3K. Given Kf = 1.86 K kg mol1, Atomic
mass : Na = 23, Cl = 35.5).
[Ans. : 0.81 mol NaCl]
12.
13.
14.
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*17. An aqueous solution of glucose boils at 100.01C. The molal boiling point
elevation constant for water is 0.5 K kg mol1. What is the number of
glucose molecule in the solution containing 100 g of water.
[Ans. : 1.2 1021 molecules]
18.
(b)
(c)
19.
(ii)
20.
The vapour pressure of pure liquids A and B are 450 and 750 mm Hg
respectively, at 350K. Find out the composition of the liquid mixture if total
vapour pressure is 600 mm Hg. Also find the composition of the vapour
phase.
[Ans. : XA = 0.4, XB = 0.6, YA = 0.3, YB = 0.7]
21.
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