Calculate molality of solution of a nonvolatile solute having boiling point elevation $1.89 \mathrm{~K}$ if…

Calculate molality of solution of a nonvolatile solute having boiling point elevation $1.89 \mathrm{~K}$ if boiling point elevation constant of solvent is $3.15 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$.
  1. $0.4 \mathrm{~m}$
  2. $0.8 \mathrm{~m}$
  3. $0.6 \mathrm{~m}$
  4. $0.3 \mathrm{~m}$

Solution

$\begin{aligned} \Delta \mathrm{T}_{\mathrm{b}} & =\mathrm{K}_{\mathrm{b}} \times \mathrm{m} \\ 1.89 & =3.15 \times \mathrm{m} \\ \therefore \quad \mathrm{m} & =\frac{1.89}{3.15}=0.6 \mathrm{~mol} \mathrm{~kg}^{-1}\end{aligned}$

Asked in: MHT CET 2023 (12 May Shift 1)

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