Question

What is the vapor pressure of a water solution at 25ºC containing glucose if the mole fraction of water is 2.0? The vapor pressure of pure water at 25ºC is 23.8 mm Hg.

Answer 1

Psolution= Xsolvent P0solvent = (2.0)(23.8 mm Hg) = 48 mm Hg

for PLATO users

Answer 2

You must use Raoult's Law: the vapor pressure of a solution is equal to the vapor pressure of the pure solvent at the same temperature times the mole fraction of the pure solvent present:

P = Xsolvent * Po

Po = 23.8 mmHg


Nevertheless there is an error in the statement because the mole fraction of any component is a solution cannot be greater than 1. So, tha the mole fraction of water is 2.0 is wrong.

I will do it assuming that the mole fraction of water is 0.98


=> P = 0.98 * 23.8 mmHg = 23.3 mmHg

Answer: 23.3 mmHg