Chemistry - Liquid Solution Question with Solution | TestHub

Given:
Mass of solute (urea), $W_2=15\text{ g}$
Molar mass of solute, $M_2=60{\text{ g mol}}^{-1}$
Mass of solvent (water), $W_1=1000\text{ g}=1\text{ kg}$
Ebullioscopic constant, $K_b=0.52{\text{ K kg mol}}^{-1}$

The molality of the solution is given by:
$m=\frac{W_2}{M_2\times W_1}$

Substituting the values:
$m=\frac{15}{60\times 1}=0.25{\text{ mol kg}}^{-1}$

The boiling point elevation is given by:
$\Delta T_b=K_b\times m$

$\Delta T_b=0.52\times 0.25=0.13\text{ K}$

Answer: 0.13 K