Glycerin, C3H8O3, is a nonvolatile liquid. What is the vapor pressure of a solution made by adding 164 g of glycerin to 325 mL of H2O at 39.8°C? The vapor pressure of pure water at 39.8°C is 54.74 torr and its density is 0.992 g/cm3.

Answer 1

Calculate moles glycerin. moles = grams/molar mass
Calculate moles H2O. Use density to obtain mass, then moles = grams/molar mass.

X = mole fraction H2O = mols H2O/total moles.
Psoln = XH2O*P^o_H2O

Answer 2

This may look a little better.
P_soln = X_H2O*P^o_H2O

Answer 3

49.958torr