Chemistry - Liquid Solution Question with Solution | TestHub

Elevation in boiling point is given by $\Delta T_b=K_{b}m$

For the boiling points to be the same, the molality of both solutions must be equal.

Molality of urea solution $=\frac{W_{\text{urea}}}{M_{\text{urea}}\times W_{\text{water (kg)}}}=\frac{5}{60\times 0.1}=\frac{5}{6}$ m

Let the mass of glucose be $x$ g.

Molality of glucose solution $=\frac{W_{\text{glucose}}}{M_{\text{glucose}}\times W_{\text{water (kg)}}}=\frac{x}{180\times 0.12}=\frac{x}{21.6}$ m

Equating the molalities:

$\frac{5}{6}=\frac{x}{21.6}$

$x=\frac{5\times 21.6}{6}=5\times 3.6=18$ g

Answer: $18$ g