If vapour pressure of pure solvent and solution are 240 and 216 $\mathrm{mm} \mathrm{Hg}$ respectively then…
If vapour pressure of pure solvent and solution are 240 and 216 $\mathrm{mm} \mathrm{Hg}$ respectively then mole fraction of solvent in solution is
- 0.9
- 0.1
- 0.6
- 0.4
Solution
$\begin{aligned}
& \mathrm{P}_1=216 \mathrm{~mm} \mathrm{Hg} . \mathrm{P}_1^0=240 \mathrm{~mm} \mathrm{Hg} \\
& \Delta \mathrm{P}=\mathrm{P}_1^0-\mathrm{P}_1=240-216=24 \mathrm{~mm} \mathrm{Hg} \\
& \text { Now, } \frac{\Delta \mathrm{P}}{\mathrm{P}_1^0}=\mathrm{x}_2 \\
& \therefore \mathrm{x}_2=\frac{24 \mathrm{mmHg}}{240 \mathrm{mmHg}}-0.1
\end{aligned}$
Hence, mole fraction of solvent, $\mathrm{x}_1=1-\mathrm{x}_2=1-0.1=0.9$
Asked in: MHT CET 2021 (20 Sep Shift 2)
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