2. A 3.37 gram sample of a nonvolatile nonelectrolyte ( no ions) is dissolved in 23.7 grams of hexane (C6H14) at 25.0 degrees calcius. The vapor pressure of pure hexane at this temperature is 438 tort, and the vapor pressure of the solution is 419.3 torr. Calculate the molecular weight of the nonelectrolyte.

Answer 1

Psoln = Xhexane*P^ohexane
Solve for Xhexane. Then 1-Xhexane = Xunknown.
nunknown/total mols = Xunknown.
Total mols = nunknown + nhexane. You have grams hexane and molar mass hexane; therefore you have n hexane. Solve for n unknown.
Then n unknown = grams/molar mass.
Solve for molar mass unknown.