Question

A solution containing $12.5$ g of non-electrolyte substance in 185 g of water shows boiling point elevation of $0.80$K. calculate the molar mass of the substance

($K_{b} = 0.52Kkgmol^{- 1}$)

• A. $53.06gmol^{- 1}$
• B. $25.3gmol^{- 1}$
• C. $16.08gmol^{- 1}$
• D. $43.92gmol^{- 1}$

Answer 1

Answer: (D)

$43.92gmol^{- 1}$

Answer 2

$M_{B} = \frac{K_{b} \times W_{B}}{\Delta T_{b} \times W_{A}} = \frac{0.52 \times 12.5}{0.80 \times 0.185} = 43.92gmol^{- 1}$

$(185g = 0.185kg)$