How to Calculate CaCl2 Concentration from Vapor Pressure Data?

[Ki-nana18]

Homework Statement

An aqueous CaCl₂ solution has a vapor pressure of 82.3 mmHg at 50 degrees C. The vapor pressure of pure water at this temperature is 92.6 mmHg. What is the concentration of CaCl₂ in mass percent?

Homework Equations

mass %=(mass of component/total mass)*100%
P_solution=X_H2OP_H2O

The Attempt at a Solution

I know I have to use Raoult's Law in order to compute the mole fraction but I'm not sure what to do after. Once I have mole fraction what do I do?

 

[Borek]

Assume 1L of the solution. Molar fraction of CaCl₂ is x, molar fraction of water is 1-x. Write definition of molar fraction, write how does the mass depend on number of moles for solvent and for solute. Mass of solvent plus mass of solute is a mass of 1L of solution. Assume density of 1 g/mL. That will give you a set of equations, you should be able to solve them for mass of solute and mass of solvent.