For non-volatile substance, relative lowering in vapour pressure of solution is equal to the mole faction of solute.
Where,
nB = Number of moles of solute
nA = Number of moles of solvent
WB = Mass of solute
WA = Mass of solvent
MB = Molecular mass of solute
MA = Molecular mass of solvent
According to. Raoult’s law
With the help of above equation we can calculate the value of molecular mass of non volatile solute, if all other factors in equation are known.
