Raoults law and Henry's law

Value of Henry’s constant KH

• increases with decrease in temperature

• decreases with increase in temperature

• increases with increase in temperature.

• remains constant

For a dilute solution, Raoult’s law that:

(a) the lowering of vapour pressure is equal to the

mole fraction of the solute

(b) the relative lowering of vapour pressure is

equal to the mole fraction of the solute

(c) the relative lowering of vapour pressure

is proportional to the amount of solute in

solution

(d) the vapour pressure of the solution is equal to

the mole fraction of the solvent

• a

• b

• c

• d

By increasing the temperature, the vapour

pressure of substance:

(a) always increases

(b) does not depend on temperature

(c) always decreases

(d) partially depends on temperature

• a

• b

• c

• d

Answer explanation

The vapour pressure at a given temperature of an

ideal solution containing 0.2 mol of a non-volatile

solute and 0.8 mol of solvent is 60 mm of Hg. The

vapour pressure of the pure solvent at the same

temperature is:

(a) 150 mm of Hg (b) 60 mm of Hg

(c) 75 mm of Hg (d) 120 mm of Hg

• a

• b

• c

• d

Molarity of liquid HCl will be, if density of

solution is 1.17 gm/cc.

(a) 36.5 (b) 32.05

(c) 18.25 (d) 42.10

• a

• b

• c

• d

• a

• b

• c

• d

Explain why aquatic species are more comfortable

in cold water rather than in warm water.

Why does soda water fizz when the bottle

is opened? Name the law that explains this

phenomenon.

The dissolution of ammonium chloride in water

is endothermic process. What is the effect of

temperature on its solubility?