QJEEM23Chddb6: JEE Main 2023 Chemistry - Class 12 JEEM23Chddb6 Solution: Mass of Urea required to be dissolved in of water in order to…

Given:

• Vapor pressure reduction: $25\%$ ( $0.75$ times the vapor pressure of pure water)


• Molar mass of water ( $\text{H}_2\text{O}$ ): $18 \, \text{g/mol}$


• Mass of solvent (water): $1000 \, \text{g}$

Using Raoult's law:

$\frac{P^0 - P_s}{P_s} = \frac{n_{\text{solute}}}{n_{\text{solvent}}} = \frac{\frac{x}{M_{\text{urea}}}}{\frac{1000}{M_{\text{water}}}} = \frac{P^0 - 0.75P^0}{0.75P^0}$

Solving for (x):

$\frac{x}{60} = \frac{10000}{9}$ $x = 1111.11111 \approx 1111 \, \text{g}$

So, the mass of urea required to be dissolved in $1000 \, \text{g}$ of water is $1111 \, \text{g}$ .