Question

An aqueous solution of 2 per cent (wt./wt.) non-volatile solute exerts a pressure of 1.004 bar at the boiling point of the solvent. What is the molecular mass of the solute?

Answer 1

Given P_s = 1.004 bar, P° = 1.013 bar (at boiling point P° = 1.013 bar = 1 atm), w = 2 g,

W- 100 - 2 = 98 g

From Raoult's law :