Question

Exercise-1

1. Concentrated nitric acid used in laboratory work is 68%

nitric acid by mass in aqueous solution. What should be

the molarity of such a sample of the acid if the density

of the solution is 1.504 g mL–1?

2. A solution of glucose in water is labelled as 10% w/w,

what would be the molality and mole fraction of each

component in the solution? If the density of solution is

1.2 g mL–1, then what shall be the molarity of the

solution?

3. A solution is obtained by mixing 300 g of 25% solution

and 400 g of 40% solution by mass. Calculate the mass

percentage of the resulting solution.

4. Why do gases always tend to be less soluble in liquids

as the temperature is raised?

5. An aqueous solution of 2% non-volatile solute exerts a

pressure of 1.004 bar at the normal boiling point of the

solvent. What is the molar mass of the solute?

6. The vapour pressure of water is 12.3 kPa at 300 K.

Calculate vapour pressure of 1 molal solution of a non-

volatile solute in it.

7. Calculate the mass of a non-volatile solute (molar mass

40 g mol–1) which should be dissolved in 114 g octane

to reduce its vapour pressure to 80%.

8. Two elements A and B form compounds having

formula AB2 and AB4. When dissolved in 20 g of

benzene (C6H6), 1 g of AB2 lowers the freezing point

by 2.3 K whereas 1.0 g of AB4 lowers it by 1.3 K. The

molar depression constant for benzene is 5.1 K kg mol–1.

Calculate atomic masses of A and B.

9. The depression in freezing point of water observed for

the same amount of acetic acid, trichloroacetic acid and

trifluoroacetic acid increases in the order given above.

Explain briefly.

10. Calculate the depression in the freezing point of water

when 10 g of CH3CH2CHClCOOH is added to 250 g

of water. Ka = 1.4 × 10–3, Kf = 1.86 K kg mol–1

11. 19.5 g of CH2FCOOH is dissolved in 500 g of water.

The depression in the freezing point of water observed

is 1.00 C. Calculate the van’t Hoff factor and

dissociation constant of fluoroacetic acid.

12. Vapour pressure of water at 293 K is 17.535 mm

Hg. Calculate the vapour pressure of water at 293 K

when 25 g of glucose is dissolved in 450 g of water.

13. Henry’s law constant for the molality of methane in

benzene at 298 K is 4.27 × 105 mm Hg. Calculate

the solubility of methane in benzene at 298 K under

760 mm Hg.

14. 100 g of liquid A (molar mass 140 g mol–1) was

dissolved in 1000 g of liquid B (molar mass 180 g

mol–1). The vapour pressure of pure liquid B was

found to be 500 torr. Calculate the vapour pressure

of pure liquid A and its vapour pressure in the

solution if the total vapour pressure of the solution

is 475 Torr.​

Answer 1

Explanation:

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