Solutions Question 2

Question: Vapour pressure of $ CCl_4 $ at $ 25^{o}C $ is $ 143mm $ of $ Hg 0.5 gm $ of a non-volatile solute (mol. wt. = 65) is dissolved in $ 100 ml CCl_4 $ . Find the vapour pressure of the solution (Density of $ CCl_4=1.58 g/cm^{2} $ ) [CBSE PMT 1998]

Options:

A) $ 141.97 $ mm Hg

B) $ 94.39 $ mm Hg

C) $ 199.34 $ mm Hg

D) $ 143.99 $ mm Hg

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Answer:

Correct Answer: A

Solution:

$ \frac{P^{0}-Ps}{P^{0}}=\frac{w\times M}{mW} $

$ =143-\frac{0.5\times 154}{65\times 158}\times 143 $

$ =143-1.03=141.97 mm Hg$ .