When 100.0 g of an unknown nonelectrolyte is dissolved in 500.0 g of benzene, C6H6, the solution boils at 82.9°C. Calculate the molecular weight (molar mass) of the unknown material. Kb for benzene is 2.53°C/m and the boiling point of pure benzene is 80.1°C?

Answer 1

delta T = Kb*m
Substitute and solve for m.

m = mols/kg solvent
Substitute and solve for mols.

mols = grams/molar mass
Substitut and solve for molar mass.