Molecular weight determination from lowering of vapor pressure
Molar mass of a solute can be found from the property of lowering of vapor pressure of a solution.
Mb = (Wb*Ma)/[Wa*(Pa°-Pa)/Pa°]
Wb = weight of solute particles, Wa= weight of solvent
(Pa°-Pa)/Pa° = decrease in vapour pressure of solution
Ma = Molar mass of solvent