Question

In 180 gram water 10 gram each of A B and C are mixed separately, then correct order of vapour pressure of thus solution is
(given molar masses of A B and C are hundred 150 and 125 gram/mole respectively)​

Answer 1

Answer:

B > C > A

Explanation:

RLVP is directly proportional to mole fraction of solute. Therefore lowering of VP in A > C > B. So VP is maximum in solution B.

Answer 2

In 180 gram water 10 gram each of A , B and C are mixed separately. molar masses of A, B and C are 100 , 150 and 125 g/mol respectively.

To find : correct order of vapor pressure of solution.

solution : mole fraction of solute A = (10/100)/(10/100 + 180/18) = 0.0099

mole fraction of solute B = (10/150)/(10/150 + 180/18) = 0.0066

mole fraction of solute C = (10/125)/(10/125 + 180/18) = 0.008

here it is clear that mole fraction of A > C > B

we know relative lowering in vapor pressure depends on mole fraction of solute.

i.e., RLVP ∝ mole fraction of solute.

⇒(P° - P)/P° ∝ mole fraction of solute.

here P is vapor pressure of solution and P° is vapor pressure of pure solvent.

here it is clear that P decreases when mole fraction increases.

therefore order of vapor pressure would be A < C < B or B > C > A