Question

On dissolving 2.34g of non-electrolyte solute in 40g of benzene, the boiling point of solution was higher than benzene by 0.81 K. Kb value for benzene in 2.53 K kgmol^-1. Calculate the molar mass of solute. [Molar mass of benzene is 78 gmol^-1]

Answer 1

K_b = 2.53 K kg mol^-1 w₁ = 40g, 

w₂ = 2.34g, M₂ = ?, ΔT_b = 0.81 K

M₂ = \(\frac{2.53\times 2.34\times 1000}{0.81\times 40}\)

= 182.7 gmol^-1