Chemistry - Liquid Solution Question with Solution | TestHub

Elevation in boiling point is given by $\Delta T_b=T_b-T_b^0$

Substituting the given values:

$\Delta T_b=319.8-319.5=0.3\mathrm{K}$

The relation between elevation in boiling point and molality is $\Delta T_b=K_b\times m$

Rearranging for molal elevation constant $K_b$:

$K_b=\frac{\Delta T_b}{m}$

$K_b=\frac{0.3}{0.12}=2.5\mathrm{K}\mathrm{kg}{\mathrm{mol}}^{-1}$

Answer: $2.5\mathrm{K}\mathrm{kg}{\mathrm{mol}}^{-1}$