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Solution 1

The document provides a series of chemistry problems and their solutions related to colligative properties, including freezing point depression, boiling point elevation, vapor pressure lowering, and osmotic pressure. Each problem includes specific data, such as molar masses and constants, and concludes with the calculated answers. The topics covered involve solutions of various solutes like ethylene glycol, glucose, and urea in different solvents.

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74 views1 page

Solution 1

The document provides a series of chemistry problems and their solutions related to colligative properties, including freezing point depression, boiling point elevation, vapor pressure lowering, and osmotic pressure. Each problem includes specific data, such as molar masses and constants, and concludes with the calculated answers. The topics covered involve solutions of various solutes like ethylene glycol, glucose, and urea in different solvents.

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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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1 ©Er. Suneel Kumar (M.Tech. M.Sc. M.Ed. B.Ed.

DQUAIC, PGDIT)

2: SOLUTION
1) What mass of ethylene glycol (molar mass 62.0 g mol-1) must be added to 5.50 gram of water to lower the
freezing point of water from 00C to – 10.0 0C? [ kf for water = 1.86 K kg mol-1] [Ans=1.843g]
2) Calculate the mass of a non-volatile solute (molar mass = 40mol-1) which should be dissolved in 114 g
octane to reduce its vapour pressure to 80%? [Ans= 8g]
3) 189 of glucose, C6H12O6 is dissolved in 1 kg of water in a saucepan. At what temperature with water boils
at 1.013 bars? Kb for water is 0.52k Kg mol-1. [Ans=373.546K]
4) Ethylene glycol (molar mass = 62g/mol) is a common automobile antifreeze. Calculate the freezing point
of the solution containing 12.4g of this substance in 100g of water. Would it be advisable to keep this
substance in the car radiator during summer? [Kf for water =1.86Kkg/mol, Kb for water =0.512K kg/mol.
[Ans=269.284K]
5) Urea forms an ideal solution in water 10% solution by mass is made at 313 K in water. Calculate the
molecular weight of urea if the vapour pressure of the solution was found to be 53.457mm of Hg at 313K.
(Vapour pressure of pure water at 313 K = 55.3mm of Hg).
[Ans=60.0 g/mol]
6) An aqueous solution of glucose boils at 100.020C. What is the number of glucose molecules in the solution
containing 100g of water? (Kb H2O =0.512K kg/mol, molar mass of solute =180g mol-1]
[Ans=1.77 7x1021 molecule]
7) 200 cm3 of an aqueous solution of a protein contains 1.26 g of protein .The osmotic pressure of this
solution at 300K is found to be 2.57×10-3bar. Calculate the molar mass of the protein.
[Ans=61110 g/mol]
8) Calculate the mass of compound (molar mass = 256g mol-1) to be dissolved in 75g of benzene to lower its
freezing point by 0.48 K. ( Kf = 5.12 K kg mol-1) [Ans=1.80 g]
9) Calculate the osmotic pressure of 40g sodium chloride in 500ml of solution at 298K assuming sodium
chloride undergoes 100% dissociation. [Ans. 66.9 atm ]
10) The degree of dissociation of BaCl2 in a dilute aqueous solution containing 2.74 g of salt per 300 gram of
water at 1000C is 80%. If the vapour pressure of water at 1000C is 750 mm Hg.Calculate the vapour
pressure of solution. [Atomic weigh of Ba=137,Cl=35.5] [Ans. 748mmHg ]
11) Calculate the boiling of a solution containing 18.4g of phenol in 500g of benzene if degree of
dimerization (α) of phenol is 60%. [Ans. 89.790c ]
Kb for Benzene = 2.53K kg mol -1, B.P. of Benzene = 80.10Cmolecular mass of Phenol = 94 g mol -1
12) 0.02 m aqueous solution of AlCl3 freezes at -0.0680C. Calculate the percentage of dissociation.
(Kf is 1.86 K/molal) [Ans. ]

2022-23

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