Question

The vapour pressure of solvent decreases by 5.4 torr when a non volatile solute is added.In this silution ,mole fraction of solute is 0.2. What would be mole fraction of the solvent if decreses in vapour pressure is 16.2 torr?

Answer 1

According to Raoult's law:

The relative lowering of vapour pressure is equal to the mole fraction of solute.

So, (p - p₀)/p = n/ (n + N)

or Δp / p = n/ (n + N)

So, 5.4 / p = 0.2

p = 27 torr

For other solution of same solvent,

Δp = 16.2 torr

16.2 / 27 = n/ (n + N)

0.6 = n/ (n + N)

Taking n + N = 1, to calculate mole fraction,

0.6 is the mole fraction of solvent. And 0.4 is the mole fraction of solute.

Answer 2

Answer:

answer is 0.4

hope it hepls