Download Problems on Solutions and colligative properties

Some problems on Solutions and Colligative
Properties
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1. With increase of temperature which of these changes?
(A) Molarity
(B) weight fraction of solute
(C) fraction of solute present in water (D) mole fraction
2. If 5.85 g of NaCl are dissolved in 90 g of water, the mole fraction of NaCl is
________.
• (A) 0.1 (B) 0.2
(C) 0.3 (D) 0.0196
2. If 5.85 g of NaCl are dissolved in 90 g of water, the mole fraction of NaCl is
________.
(A) 0.1 (B) 0.2
(C) 0.3 (D) 0.0196
3. The mole fraction of a solute in one molal aqueous solution is
_________.
(A) 0.027 (B) 0.036
(C) 0.018 (D) 0.008
4. To prepare a solution of concentration of 0.03 g/mL of AgNO3 , what
amount (g) of AgNO3 should be there in 60 mL of solution?
(A) 1.8 (B) 0.8
(C) 0.18 (D) none of these
5. What is the molarity of H2SO4 solution, that has a density of 1.84
g/cc at 35°C and contains solute 98% by weight?
(A) 4.18 M (B) 8.14 M (C) 18.4 M (D) 18 M
Problem based on Henry’s law
• Consider two water samples, one from Bombay and the other from
Kathmandu (Nepal). If the temp. is the same at both the places, which
one will have more oxygen dissolved?
• Solution: The partial pressure of oxygen will NOT be the same for
both samples as the atmospheric pressure is the maximum at sea
level and it decreases with increase in altitude.
• Thus according to Henry’s law, the x ( mole fraction ) of oxygen will be
less at Kathmandu.
6. The density (in g mL-1) of a 3.60 M sulphuric acid solution that is 29%
H2SO4 (molar mass = 98 g mol-1) by mass will be_______.
(A) 1.22 (B) 1.45
(C) 1.64 (D) 1.88
7. If 5.85 g of NaCl (molecular mass 58.5) is dissolved in water and the
solution is made up to 0.5 litre, the molarity of the solution will be
_______.
(A) 0.2 (B) 0.4 (C) 1.0 (D) 0.1
8. What will be the molarity of a solution containing 5 g of sodium
hydroxide in 250 mL solution?
(A) 0.5 (B) 1.0 (C) 2.0 (D) 0.1
9. 25 mL of a solution of barium hydroxide on titration with a 0.1 molar
solution of hydrochloric acid gave a titrate value of 35 mL. The molarity
of barium hydroxide solution was ______.
(A) 0.07
(B) 0.14 (C) 0.28
(D) 0.35
10. Two solutions of a substance (non-electrolyte) are mixed in the
following manner: 480 mL of 1.5 M first solution + 520 mL of 1.2 M
second solution. What is the molarity of the final mixture?
(A) 1.20 M
(B) 1.50 M
(C) 1.344 M
(D) 2.70 M
11. The percent weight of NaOH in 1.25 molal sodium hydroxide solution is
__________.
(A) 5
(B) 12.5
(C) 4.76 (D) 1.25
12. 0.2 molal NaOH solution is prepared in water (density of H2O is 1 kg
dm-3). Mole fraction of solute is ______.
(A) 3.6 X 10-3
(B) 3.6 X 10-5
(C) 3.3 X 10-4
(D) 3.58 X 10-4
12. 0.2 molal NaOH solution is prepared in water (density of H2O is 1 kg dm-3). Mole
fraction of solute is ______.
(A) 3.6 X 10-3
(B) 3.6 X 10-5
(C) 3.3 X 10-4
(D) 3.58 X 10-4
Mole fraction = mole of NaOH / total moles
= 0.2 / (1000/18)
= 0.2 / 55.56
( please remember the value of 1000/18 to save time)
= 0.4 / 111
= 0.004 This is higher value by 10 % approximately than 0.4/111
= to nullify the effect of approximation,10 % should be reduced from 0.004
= 0.0036
= 3.6 X 10-3
13. What is the molality of solution containing 200 mg of urea (molar
mass: 60 g mol-1) dissolved in 40 g of water?
(A) 0.08325 (B) 0.825 (C) 0.498 (D) 0.0013
14. What will be the molality of solution having 18 g of glucose
(molecular weight = 180) dissolved in 500 g of water?
(A) 1 mol kg-1
(B) 0.5 mol kg-1
(C) 0.2 mol kg-1 (D) 2 mol kg-1
15. Which one of the statements given below concerning properties of solutions
describes a colligative effect?
(A) boiling point of pure water decreases by the addition of ethanol
(B) vapour pressure of pure water decreases by the addition of nitric acid
(C) vapour pressure of pure benzene decreases by the addition of naphthalene
(D) boiling point of pure benzene increases by the addition of toluene
16. Which of the following is a colligative property?
(A) viscosity
(B) surface tension
(C) refractive index
(D) osmotic pressure
17. Equimolar solutions of nonionic solutes in the same solvent have ________.
(A) same boiling point but different freezing point
(B) same freezing point but different boiling point
(C) same boiling and same freezing point
(D) different boiling and different freezing points
18. Vapour pressure of CCl4 at 25°C is 143 mm of Hg. 0.5 g of a non volatile solute
(molecular mass = 65) is dissolved in 100 mL CCl4 find the vapour pressure of the
solution
(Density of CCl4 = 1.58 g/cm³)
(A)141.93 mm
(B) 94.39 mm
(C) 199.34 mm
(D) 143.99 mm
19. Benzene and toluene from nearly ideal solution. At 20 °C the vapour pressure of
benzene is 75 torr and that of toluene is 22 torr. The partial vapour pressure of
benzene at 20 °C for a solution containing 78 g of benzene and 46 g of toluene in
torr is _________.
(A) 50
(B) 25
(C) 37.5
(D) 53.5
20. In an experiment, 1 g of a non volatile solute was dissolved in 100 g of acetone
(molar mass = 58 ) at 298 K. The vapour pressure of the solution was found to be
192.5 mmHg. Molecular weight of solute is __________. (vapour pressure of
acetone = 195 mmHg)
(A) 25.24
(B) 35.24
(C) 45.24
(D) 55.24
21. 9 g of glucose ( mol wt 180 ) is dissolved in 90 g of H2O. Relative
lowering of vapour pressure is _________.
(A) 0.99
(B) 0.099
(C) 0.0099
(D) 0.00099
21. 9 g of glucose ( mol wt 180 ) is dissolved in 90 g of H2O. Relative
lowering of vapour pressure is _________.
(A) 0.99
(B) 0.099
(C) 0.0099
(D) 0.00099
22. Vapour pressure of pure solvent and its solution at certain temperature are 660
mm and 600 mm of Hg respectively. If 3.6 X 10-³ kg of solute is added into 40 x 10-³
kg of solvent what is the molar mass of solute ? ( Solvent=benzene, C=12, H=1)
(A) 78.0 g mol-1
(B) 58.5 g mol-1
(C) 60.0 g mol-1
(D) 156 g mol-1
23. Which one of the following aqueous solutions will exhibit highest boiling point ?
(A) 0.015 M urea (B) 0.01 M KNO3 (C) 0.01 M Na2SO4 (D) 0.015 M glucose
24. Pressure cooker reduce cooking time for food because __________.
(A) it is more evenly distributed in the cooking space
(B) boiling point of water involved in cooking is increased
(C) the higher pressure inside the cooker crushes the food material
(D) cooking involves chemical changes helped by rise in temperature
25. The elevation in boiling point of a solution of 13.44 g of CuCl2 in 1 kg of water
will be_____________. ( Molecular mass of CuCl2 = 134.4 and Kb= 0.52 K m-1)
(A) 0.16
(B) 0.05
(C) 0.1
(D) 0.2
25. The elevation in boiling point of a solution of 13.44 g of CuCl2 in 1 kg of water
will be_____________. ( Molecular mass of CuCl2 = 134.4 and Kb= 0.52 K m-1)
(A) 0.16
(B) 0.05
(C) 0.1
(D) 0.2
26. The boiling point of water (100°C) becomes 100.52°C if 3 grams of a non
volatile solute is dissolved in 200 mL of water. The molecular weight of solute is
____________. (kb for water is 0.6 k kg mol-1)
(A) 12.2 g/mol (B) 15.4 g/mol
(C) 17.3 g/mol
(D) 20.4 g/mol
27. The boiling point of a solution of 0.11 g of substance in 15 g of ether was found
to be 0.1 °C higher than that of the pure ether. The molecular weight of the
substance will be _____________. (Kb = 2.16 k kg mol-1)
(A) 148 g mol-1
(B) 158 g mol-1
(C) 168 g mol-1
(D) 178 g mol-1
27. The boiling point of a solution of 0.11 g of substance in 15 g of ether was found
to be 0.1 °C higher than that of the pure ether. The molecular weight of the
substance will be _____________. (Kb = 2.16 k kg mol-1)
(A) 148 g mol-1
(B) 158 g mol-1
(C) 168 g mol-1
(D) 178 g mol-1
28. In the depression of freezing point experiment, it is found that the
____________.
(A) Molality of the solution decreases
(B) vapour pressure of the solution is more than that of pure solvent
(C) only solute molecules solidify at the freezing point
(D) only solvent molecules solidify at the freezing point
29. The freezing point of equimolal aqueous solution will be highest for
___________.
(A) C6H5NH+3CI-
(B) Ca(NO3)2
(C) Al2(SO4)3
(D) K2SO4
29. The freezing point of equimolal aqueous solution will be highest for
___________.
(A) C6H5NH+3CI-
(B) Ca(NO3)2
(C) Al2(SO4)3
(D) K2SO4
30. Of the following 0.10 m aqueous solutions, which one will be exhibit the largest
freezing point depression?
(A) KCl
(B) C6H12O6 (C) Al2(SO4)3 (D) K2SO4
31. Equimolar salt solution of which of the following will show the maximum
depression in freezing point?
(A) sodium sulphate
(C) magnesium sulphate
(B) potassium chloride
(D) magnesium carbonate
32. A 0.2 molar aqueous solution of a weak acid (HX) is 20% ionised. The freezing
point of the solution is _____________. (given kf=1.68°C/m for water)
(A) -0.31° C
(C) -0.53° C
(B) -0.45° C
(D) -0.90° C
33. After adding a solute freezing point of the solution decreases to -0.186.
Calculate ∆Tb if Kf = 1.86 and Kb = 0.521.
(A) 0.521
(C) 1.86
(B) 0.0521
(D) 0.0186
34. The freezing point of a solution containing 4.8 g of a compound in 60 g of
benzene is 4.48 °C. What is the molar mass of the compounds ? (Kf 5.1 km-1,
freezing point of benzene 5.5° C)
(A) 100 g mol-1
(B) 200 g mol-1
(C) 300 g mol-1
(D) 400 g mol-1
35. An aqueous solution of a weak monobasic acid containing 0.1 g in 21.7 g of
water freezes at 272.813 K. If the value of Kf for water is 1.86 k/m, what is the
molecular mass of the monobasic acid? (Assume the value of f.p. of solvent as
273.150 K)
(A) 50.0 g/mol
(B) 46.2 g/mol
(C) 55.5 g/mol
(D) 25.4 g/mol
35. An aqueous solution of a weak monobasic acid containing 0.1 g in 21.7 g of
water freezes at 272.813 K. If the value of Kf for water is 1.86 k/m, what is the
molecular mass of the monobasic acid? (Assume the value of f.p. of solvent as
273.150 K)
(A) 50.0 g/mol
(B) 46.2 g/mol
(C) 55.5 g/mol
(D) 25.4 g/mol
36. When 0.08 kg of a solute (mol.wt = 62) is dissolved in 400 g of water (freezing
point of water = 273.13 K, Kf = 1.86), the freezing point of mixture is
approximately_____________.
(A) 268.13 K
(C) 266.13 K
(B) 271.63 K
(D) 269.13 K
37. Find the Kf if 6 g of urea is dissolved in in 0.1 dm³ of water and its corresponds
to 0.15° C in ∆Tf. (molecular weight of urea = 60 g mol-1)
(A) 0.015
(B) 0.15
(C) 0.30
(D) 0.030
38. For 0.1 M of NaCl and 0.1 M of Na2SO4 solution, which of the following
statement is true ?
(A) osmotic pressure of both the solution are same
(B) osmotic pressure of NaCl solution will be more than Na2SO4 solution
(C) osmotic pressure of Na2SO4 solution will be more than NaCl
(D) osmotic pressure of Na2SO4 will be less than that of NaCl solution
39. 30 x 10-4 kg of urea dissolved in water to make 500 mL aqueous solution . This
solution is isotonic with cane sugar solution. How much mass of cane sugar is in
one litre solution ? ( H = 1, N= 14, O=16 C=12)
(A) 17.1 g
(C) 3.41 g
(B) 171.0 g
(D) 34.2 g
40. In an experiment, 1 g of a non volatile solute was dissolved in 100 g of acetone (
molecular mass = 58) at 298 K. The vapour pressure of the solution was found to be
192.5 mm Hg. The molecular weight of the solute is ________. ( Vapour pressure of
acetone = 195 mm Hg)
(A) 25.24
(B) 35.24
(C) 45.24
(D) 55.24
41. The boiling point of water becomes 100.52 °C ,if 3 g of non volatile solute is
dissolved in 200 mL of water. The molecular weight of solute is______________. (
Kb for water is 0.6 K/m )
(A) 12.2 g/mol
(C) 17.3 g/mol
(B) 15.4 g/mol
(D) 29.4 g/mol
42. van't Hoff equation for osmotic pressure of dilute solution is given as
_____________.
(A) πV = K
(C) π = W2RT/M2
(B) πV = W2RT/M2
(D) πV = cRT
43. van't Hoff factor for aqueous monofluoroacetic acid is______________.
(A) i = 1 + 2 α
(B) i = 1 -2 α
(C) i = 1 + α
(D) i = 1 – α
44. Which of the following salt has the same value of van't Hoff factor (i) as that
K4[Fe(CN)6]?
(A) Al2(SO4)3
(B) NaCl
(C) Na2SO4
(D) Al(NO3)3
44. Which of the following salt has the same value of van't Hoff factor (i) as that
K4[Fe(CN)6]?
(A) Al2(SO4)3
(B) NaCl
(C) Na2SO4
(D) Al(NO3)3
45. If α is the degree of dissociation of Na2SO4 the van’t Hoff factor (i) used for
calculating the molecular mass is _____________.
(A) 1 + α
(C) 1 + 2 α
(B) 1 – α
(D) 1- 253
44. Which of the following salt has the same value of van't Hoff (i) as that
K4[Fe(CN)6] ?
(A) Al2(SO4)3
(C) Na2SO4
(B) NaCl
(D) Al(NO3)3
46. Which of the following is not a a colligative property ?
(A) elevation in boiling point
(B) Relative lowering of vapour pressure
(C) osmotic pressure
(D) freezing point
47. Which one of the following statement is false?
(A) The correct order of osmotic pressure for 0.01 M aqueous solution of each
compound is
BaCI2 > KCI > CH3COOH > Sucrose
(B) The osmotic pressure (π) of a solution is given by the equation π = MRT where
M is the molarity of the solution.
(C) Raoult’s law states that the vapour pressure of a component over a solution is
proportional to its mole fraction.
(D) Two sucrose solutions of same molarity prepared in different solvent will have
the same freezing point depression
48. A solution of Al2(SO4)3 (d = 1.253 g/mL ) contains 22% salt by weight. The
molarity and molality of the solution is_______________.
(A) 0.805 M, 0.825 m
(B) 0.825 M, 0.805 m
(C) 4.83 M, 4.83 m
(D) 4.83 M, 48.3 m
49. The vapour pressure of a solvent A is 0.80 atm. When a nonvolatile substance B
is added to this solvent its vapour pressure drops to 0.6 atm. What is the mole
fraction of B in the solution ?
(A) 0.25
(C) 0.75
(B) 0.50
(D) 0.90
50. The mole fraction of the solute in one molar aqueous solution is
_____________.
(A) 0.027
(C) 0.018
(B) 0.036
(D) 0.009
50. The mole fraction of the solute in one molar aqueous solution is
_____________.
(A) 0.027
(C) 0.018
(B) 0.036
(D) 0.009
51. how many grams of concentrated nitric acid solution should be used to prepare
250 mL of 2.0 M HNO3 ? The concentrated acid is 70% HNO3
(A) 45.0 g conc. HNO3
(B) 90.0 g conc. HNO3
(C) 70.0 g conc. HNO3
(D) 54.0 g conc. HNO3
52. 6.02 X 10²0 molecules of urea are present in 100 mL of its solution. The
concentration of solution is___________.
(A) 0.02 M
(C) 0.001 M
(B) 0.01 M
(D) 0.1 M
52. 6.02 X 10²0 molecules of urea are present in 100 mL of its solution. The
concentration of solution is___________.
(A) 0.02 M
(C) 0.001 M
(B) 0.01 M
(D) 0.1 M