The vapour pressure of pure CHCl_3 and CH_2 Cl_2 are 200 and 41.5 atm respectively. The weight of CHCl_3 and CH_2 Cl_2 are 11.9 ~g and 17 ~g respectively in a solution. The vapour pressure of solution (in atm) will be

Correct answer: C. 94.3 aligned & (c) : p_ CHCl_3 ^ o =200 atm ; p_ CH_2 Cl_2 ^ o =41.5 atm & n_ CHCl =11.9 / 119.5=0.1, n_ CH_2 Cl_2 =17 / 85=0.2 & P_T=p_A^ o x_A+p_B^ o x_B & =200 ×(0.1 / 0.3)+41.5 ×(0.2 / 0.3)=94.3 atm aligned

AIIMS 201925 May

Exam: AIIMS
Year: 2019
Date: 25 May
Subject: Chemistry
Chapter: Solutions

AIIMS 2019 · 25 May · Chemistry · Solutions

The vapour pressure of pure CHCl_3 and CH_2 Cl_2 are 200 and 41.5...

The vapour pressure of pure

\mathrm{CHCl}_3

and

\mathrm{CH}_2 \mathrm{Cl}_2

are 200 and 41.5 atm respectively. The weight of

\mathrm{CHCl}_3

and

\mathrm{CH}_2 \mathrm{Cl}_2

are

11.9 \mathrm{~g}

and

17 \mathrm{~g}

respectively in a solution. The vapour pressure of solution (in atm) will be

Options

A $80.5$
B $79.5$
C $94.3$
D $105.5$

Correct answer

C. $94.3$

Step-by-step solution

\begin{aligned} & \text{ (c) }: p_{\mathrm{CHCl}_3}^{\mathrm{o}}=200 \mathrm{ atm} ; p_{\mathrm{CH}_2 \mathrm{Cl}_2}^{\mathrm{o}}=41.5 \mathrm{ atm} \\ & n_{\mathrm{CHCl}}=11.9 / 119.5=0.1, n_{\mathrm{CH}_2 \mathrm{Cl}_2}=17 / 85=0.2 \\ & P_T=p_A^{\mathrm{o}} x_A+p_B^{\mathrm{o}} x_B \\ & =200 \times(0.1 / 0.3)+41.5 \times(0.2 / 0.3)=94.3 \mathrm{ atm}\end{aligned}

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