Biphenyl, C12H10, is a nonvolatile, nonionizing solute that is soluble in benzene, C6H6. At 25 °C, the vapor pressure of pure benzene is 100.84 torr. What is the vapor pressure of a solution made from dissolving 18.9 g of biphenyl in 26.4 g of benzene?

Answer 1

mols biphenyl = g/molar mass
mols benzene = g/molar mass
mol fraction benzene = Xbenzene = mols benzene/total mols.
Then pbenzene = Xbenzene*P^o_{normal v.p.}