Chemistry - Liquid Solution Question with Solution | TestHub

$\frac{{\text{p}}_{\text{0}}-{\text{p}}_{\text{S}}}{{\text{p}}^{\text{0}}}\text{=}{\text{x}}_{\text{Solute}}$
$\text{=}\frac{\frac{{\text{W}}_{\text{Solute}}}{{\text{M}}_{\text{Solute}}}}{\frac{{\text{W}}_{\text{Solute}}}{{\text{M}}_{\text{Solute}}}\text{+}\frac{{\text{W}}_{\text{Solvent}}}{{\text{M}}_{\text{Solvent}}}}$
$\frac{{{\mathrm{P}}^0-\mathrm{P}}_{\mathrm{S}}}{{\mathrm{P}}_0}=\frac{{\mathrm{w}}_{\mathrm{A}}}{{\mathrm{m}}_{\mathrm{A}}}\times \frac{{\mathrm{m}}_{\mathrm{B}}}{{\mathrm{W}}_{\mathrm{B}}}$(A stands for solute and B for solvent)
$\frac{\mathrm{x}-\mathrm{x}\times \frac{75}{100}}{\mathrm{x}\times \frac{75}{100}}=\frac{\mathrm{w}}{60}\times \frac{18}{100}$
[Let the vapour pressure of pure water,${\mathrm{P}}^0=\mathrm{x}$]
$\frac{0.25\mathrm{x}}{0.75\mathrm{x}}=\frac{\mathrm{w}}{60}\times \frac{18}{100}$
$\therefore \mathrm{w}=111.118$
$\text{Molality}=\frac{111.11}{60}\times \frac{1000}{100}=18.52$