Question

An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. What is the molar mass of the solute? 

Answer 1

Vapour pressure of the solution at normal boiling point (p_¹) = 1.004 bar

 Vapour pressure of pure water at normal boiling point (p^o₁ )=1.013 bar

Mass of solute, (w²⁾ = 2 g

 Mass of solvent (water), (w¹) 

= 98 g Molar mass of solvent (water), (M¹)

 = 18 g mol−¹ According to Raoult’s law,