colligative properties 10 que

PHYSICAL CHEMISTRY B y : Shailendra Kumar 1. Op p. Khuda Bak sh Libr ar y , Ash ok Ra jp ath, Patna - 4 2. Hous e n o. 5A/65, Opp. Mahual Koth i, Al pana Mar ket, Patna Page No.: 1 1. 10 g of a c ertain non-volatile solute were di ssolved in 100 g water at 20° C. The vapour pressure was lowered from 17.3555 mm to 17.2350 mm, calculate m. wt. of solute. An s: m = 257.45 2. The vapour pressure of pure benzene at 25° C is 639.7 mm of Hg and the vapour pressure of a solution of a solute in C 6 H 6 at the same temperature is 631.9 mm of Hg. Calculate molality of solution. Ans: 0.158 mol /kg of solvent 3. The vapour pressure of water at 20° C is 17.54 mm. When 20 g of solute was add ed in 100 g water, the V .P . was found to lower by 0.30 mm. Calculate M.wt. of solute. Ans: m = 206.88 4. The vapour pressure of pure benzene at a c ertain temperature is 640 mm o f Hg. A non- volatile non-electrolyte solid weighing 2.1/5 g is added to 39.0 g of benzene. The vapour pressure of the solution is 600 mm of Hg. What is the molecular weight of solid substance. An s: m = 65.25 5. The vapour pressure of an aqueous solution of gl ucose is 750 mm of Hg at 373 K. Calculate molality and mole fraction of solute. Ans: 0.741 mol/k g of solv ent & 0.0 13 6. What weight of solute (M.wt. 60) is required to dissolve in 180 g of water to reduce the vapour pressure to 4/5th of pure water? Ans: 150 g PH YSICA L CH EMIST RY SCIENCE TUTORIALS; Opp. Khuda Baksh Library, Ashok Rajpath, Patna PIN POINT STUDY CIRCLE; House No. 5A/65, Opp. Mahu al Kothi, Alpana Market , Patna Topic: Colligative Property (Relative lowering of vapour pressure) Clas s es at: - b y: SHAIL E ND RA KR. Meq. Appr oach

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7/27/2019 Colligative Properties 10 Que

http://slidepdf.com/reader/full/colligative-properties-10-que 1/2

PHYSICAL CHEMISTRY By : Sh a i l en d r a K um a r

1. Opp. Khuda Baksh Library, Ashok Rajpath, Patna - 42. House no. 5A/65, Opp. Mahual Kothi, Alpana Market, Patna

Page No.: 1

1. 10 g of a certain non-volatile solute were dissolved in 100 g water at 20°C. The vapourpressure was lowered from 17.3555 mm to 17.2350 mm, calculate m. wt. of solute.

Ans: m = 257.45

2. The vapour pressure of pure benzene at 25°C is 639.7 mm of Hg and the vapour pressureof a solution of a solute in C

6at the same temperature is 631.9 mm of Hg. Calculate

molality of solution.

Ans: 0.158 mol/kg of solvent

3. The vapour pressure of water at 20°C is 17.54 mm. When 20 g of solute was added in100 g water, the V.P. was found to lower by 0.30 mm. Calculate M.wt. of solute.

Ans: m = 206.88

4. The vapour pressure of pure benzene at a certain temperature is 640 mm of Hg. A non-volatile non-electrolyte solid weighing 2.1/5 g is added to 39.0 g of benzene. The vapourpressure of the solution is 600 mm of Hg. What is the molecular weight of solid substance.

Ans: m = 65.25

5. The vapour pressure of an aqueous solution of glucose is 750 mm of Hg at 373 K. Calculatemolality and mole fraction of solute.

Ans: 0.741 mol/kg of solvent & 0.013

6. What weight of solute (M.wt. 60) is required to dissolve in 180 g of water to reduce the

vapour pressure to 4/5th of pure water?

Ans: 150 g

PHYSICAL CHEMISTRY

SCIENCE TUTORIALS; Opp. Khuda Baksh Library, Ashok Rajpath, Patna

PIN POINT STUDY CIRCLE; House No. 5A/65, Opp. Mahual Kothi, Alpana Market,Patna

Topic: Colligative Property (Relative lowering of vapour pressure)

Classes at: -

by: SHAILENDRA KR.Meq. Appr oach