Question

If 0.220 molmol of a nonvolatile nonelectrolyte are dissolved in 3.70 molmol of water, what is the vapor pressure PH2OPH2O of the resulting solution? The vapor pressure of pure water is 23.8 torrtorr at 25 ∘C∘C .

Answer 1

Answer:

Vapor pressure for solution is 22.4 Torr

Explanation:

P° → Vapor pressure of pure solvent

P' → Vapor pressure of solution

Formula for lowering vapor pressure is: P° - P' = P°  . Xm

Xm is the mole fraction. Let's determine it:

0.220 mol of solute + 3.70 mol of water = 3.92 total moles

Mole fraction for solute → 0.220 / 3.92 = 0.056

23.8 Torr - P' = 23.8 Torr  . 0.056

P' = - ( 23.8 Torr  . 0.056 - 23.8 Torr ) → 22.4 Torr