Gudha Public School, Neemka Thana

Summer Vacations Home Work

Numerical
Concentration of the solution & Mole fraction

1. Calculate the mol fraction of ethylene glycol ( C2H6O2) in a solution containing 20% of C2H6O2 by mass is
aqueous solution. [Ans: 0.069]
2. A solution contains 25% H2O , 25% C2H5OH and 50% CH3COOH by mass . Calculate the mole fraction of each
component. [ Ans: X H20 = 0.501 , x C 2 H 5 OH = 0.196 , x CH 3 COOH =0.301 ]
3. An antifreeze solution is prepared from 222.6 g of ethylene glycol , C 2H4(OH)2 and 200 g of water. Calculate
the molality of the solution. If the density of the solution is 1.072 g mL -1, then what shall be the molarity of
the solution? [ Ans molality : 17.95 , molarity : 9.1]
4. 6.90 M solution of KOH in water containing 30% by mass of KOH. Calculate the density of KOH solution.
[ Ans : 1.29 g cm-3 ]
5. 4.0 g of NaOH are contained in one decilitre of a solution. Calculate (i) mole fraction of NaOH (ii) molarity of
NaOH (iii) molality of solution. ( density of solution = 1.038 g mL-1) [ Ans : 7.6M , 11.4 m ]

Solubility and Henry’s Law

6. How many kilogram of oxygen gas can dissolve in 1 dm3 of water at 200C if its partial pressure is 0.20 atm. KH
for O2 at 20oC is 4.58 ×104 atm? [ Ans : 7.8 ×10-6 Kg]
7. Henry’s law constant for CO2 in water is 1.67 ×108 pa at 298K. Calculate the quantity of CO2 is 500 mL of
soadwater when packed under 2.5 atm CO2 pressure at 298K. [ Ans : 1.834 g ]
8. If the solubility product of CuS is 6 ×10-16, calculate the maximum molarity of CuS in aqueous solution.
[ Ans : 2.45 × 10-8 mol L-1 ]
9. The partial pressure of ethane over a saturated solution containing 6.56×10-2 g of ethane is 1 bar. If the
solution contains 5.0 × 10-2 g of ethane, then what will be the partial pressure of the gas?
[ Ans: 0.762 bar ]
Vapour pressure of Liquid Solution
10. The vapour pressures of ethanol and methanol are 44.5 mmHg and 88.7 mmHg respectively. An ideal
solution is formed at the same temperature by mixing 60 g of ethanol with 40 g of methanol. Calculate the
total vapour pressure of the solution and the mole fraction of methanol in the vapour.
[ Ans: 66.15 mm Hg , 0.657 ]
11. An aqueous solution of glucose is made by dissolving 10 g of glucose ( C6H12O6) in 90 g of water at 303k. If
vapour pressure of pure water at 303K is 32.8 mm Hg, what would be vapour pressure of solution?
[ Ans : 32.44 mm
Hg]
12. Two liquids X and Y on mixing from ideal solution. The vapour pressure of solution containing 3 mol of X
and 1 mol of Y is 550 mm Hg. But when 4 mol of X and 1 mol of Y are mixed the vapour pressure is 560 mm
of Hg. Calculate the vapour pressures of pure X and Y. [ Ans : 600 mm Hg , 400 mm Hg]
13. The liquids X and Y from ideal solution having vapour pressures 200 and 100 mm Hg respectively. Calculate
the mole fraction of component X in vapour phase in equilibrium with an equimolar solution of the two.
[ Ans : 0.67 ]
14. The vapour pressure of pure liquids A and B are 450 mm and 700 mm of Hg respectively at 350 K. Find out
the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also, find the composition in
the vapour phase. [ Ans : PA = 180mmHg, PB=420mmHg, Mole fraction A = 0.30 , B= 0.70]
Elevation of Boiling Point
15. Calculate boiling point of 1 molar aqueous solution of a solute ( Molar mass = 74.5 gmol -1). The density of
solution is 1.04 g mL-1 and Kb for water is 0.52 K Kgmol-1. [ Ans : 100.536oC]
16. What would be the molar mass of the compound if 6.21 g of it is dissolved in 24.0g of chloroform to form a
solution that has a boiling point of 68.04oC. The boiling point of pure chloroform is 61.7oC and boiling
point elevation constant (Kb) of chloroform is 3.63oc/m. [ Ans : 148.15 g mol-1]
17. 10 gram of a non-volatile solute when dissolved in 100 gram of benzene raises its boiling point by 1 o What is
the molecular mass of the solute? ( Kb for benzene = 2.53 Kmol-1) [ Ans : 253 ]
18. On dissolving 3.24 g of sulphure in 40 g of benzene, boiling point of solution was higher than that of
benzene by 0.81K. Kb value for benzene is 2.53K kg mol-1. What is the molecular formula of sulphur?
( Atomic mass of sulphur = 32 g mol-1) [ Ans : S 8
]
19. A solution containing 12.5 g of a non- electrolyte substance in 175 g of water gave boiling point elevation
of 0.70K. calculate the molar mass of the substance. ( Kb for water = 0.52 K kg mol-1 )
[ Ans : 53.06]
Depression in Freezing Point
20. Ethylene glycol ( molar mass = 62 gmol-1) is a common automobile antifreeze. Calculate the freezing point
of a solution containing 12.4 g of this substance in 100 g of water. Would it be advisable to keep this
substance in car radiator during summer? ( Kf for water = 1.86 K m-1 and Kb for water = 0.512 K m-1 )
[ Ans : 374.19 K ]
21. In a cold climate water gets frozen causing damage to the radiator of a car. Ethylene glycol is used as an
antifreezing agent. Calculate the amount of ethylene glycol to be added to 4 Kg of water to prevent it from
freezing at -6OC. ( Kf for water = 1.85 Km-1) [ Ans : 804.32g]
22. 15.0 f of an unknown molecular material is dissolved in 450 g of water. The resulting solution freezes at –
0.34oC. What is the molar mass of the material? [ Ans: 182.35 g mol -1]
23. A solution of glucose ( Molar mass = 180 g mol-1) in water has a boiling point of 100.20oC. Calculate the
freezing point of the same solution. Molal constants for water Kf and Kb are 1.86 K kg mol-1 and 0.512 K kg
mol-1 respectively. [ Ans : 272.425K]

Osmotic Pressure

24. At 300K, 36 g of glucose, C6H12O6 present per litre in its solution has an osmotic pressure of 4.98 bar. If the
osmotic pressure of another glucose solution is 1.52 bar at the same temperature, calculate the
concentration of the other solution. [ Ans : 0.061 M]
25. A solution prepared by dissolving 8.95 mg of a gene fragment in water to from 35.0 ml of solution. The
osmotic pressure of the solution at 25oC is 0.335 torr. Assuming gene fragment to be non-electrolyte,
calculate its molar mass. [ Ans : 14201.4 g mol -1]
26. A solution containing 13.5 g urea per 500 mL of solution in water has same osmotic pressure as a solution
of sucrose ( C12H22O11)in water. Calculate the mass sucrose present in 500 mL of its solution.
[Ans :76.95 g]
27. Osmotic pressure of a solution containing 7 g of a protein per 100 mL of solution is 25 mmHg at 37 oC.
Calculate the molar mass of the protein. [ Ans: 54093 g mol -1]
28. 100 mg of a protein is dissolved in enough water to make 10 mL of a solution. If this solution has osmotic
pressure of 13.3 m,m Hg at 25oC, what is the molar mass of protein. [Ans : 13963.4 g mol-1]
Abnormal colligative properties
29. Calculate the amount of KCl which must be added to 1 kg of water so that freezing point is depressed by 2
K ( Kf for water = 1.86 K kg mol-1] [Ans: 40.05g]
30. 1.0 molal aqueous solution of trichloroacetic acid (CCl3COOH) is heated to its boiling point. The solution
has a boiling point of 100.18oC. Determine the Van’t Hoff factor for trichloroacetic acid . ( Kb for water =
0.512 K kg mol-1 ). [ Ans : 0.35]
31. Calculating the freezing point of aqueous solution containing 10.50 g MgBr 2 in 200 g of water ( Kf for water
is 1.86 K kg mol-1, and molar mass of MgBr2 = 184 g mol-1). [ Ans : - 1.59OC]
32. What mass of NaCl must be dissolved in 65.0 g of water to lower the freezing point of water by 7.5 oC. The
freezing point depression constant (Kf) for water is 1.86oC/m. Assume van’t Hoff factor for NaCl to be 1.87
and molar mass of NaCl is 58.5 g mol-1. [ Ans : 8.2 g]
33. A solution of containing 3.100 g of BaCl2 in 250 g of water boils at 100.083oC. Calculate the values of Van’t
Hoff’s factor and molarity of BaCl2 in the solution. ( Kb for H2O = 0.52 K kg mol-1]
[ Ans : i=2.86 , Molality = 0.059 mol Kg -1]
34. A freezing point depression of 0.1m NaCl solution is 0.372oC. What conclusion would you draw about the
state of NaCl in solution? Kf for water = 1.86 K kg mol-1 . [ Ans : completely ionised]
35. What is the freezing point of 0.4 molal solution of acetic acid in benzene in which it dimerises to the
extent of 85%? Freezing point of benzene is 278.4K and its molar heat of fusion is 10.042 KJmol -1.
[Ans: 277.25
K]
36. Calculate the mass of NaCl ( molar mass = 58.5 g mol-1) to be dissolved in 37.2 g of water to lower the
freezing point by 2oC, assuming that NaCl undergoes complete dissociation. ( Kf for water = 1.86 K kg mol-1)
[ Ans : 1.17 g]