1. Tardigrade
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  3. Chemistry
  4. The vapour pressure of a solvent decreases by 10 mm of Hg than a non-volatile solute was added is 0.2 . What should be the mole fraction of the solvent if the decrease in vapour pressure is to be 20 mm of Hg.

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Q. The vapour pressure of a solvent decreases by $10 \,mm$ of $Hg$ than a non-volatile solute was added is $0.2 .$ What should be the mole fraction of the solvent if the decrease in vapour pressure is to be $20\, mm$ of $Hg$.

Solutions

Solution:

$P ^{\circ}- P =10$

Apply, $\frac{ P ^{\circ}- P _{ s }}{ P ^{\circ}}= x _{ B }$

$\frac{10}{ P ^{\circ}}=0.2 \Rightarrow P ^{\circ}=50$

Then, $P ^{\circ}- P _{ s }=20$

$\frac{P^{0}-P_{s}}{P^{0}}=x_{B}$

$\Rightarrow \frac{20}{50}=x_{B}=0.4$

$\left(\because x_{A}+x_{B}=1\right)$

$\therefore x_{A}=0.6$