Verified Solution • 2025–26 Session moderate

QJEEM23Chdab3: JEE Main 2023 Chemistry - Class 11 JEEM23Chdab3 Solution: Some amount of dichloromethane is added to of chloroform to…

Some amount of dichloromethane $\left(\mathrm{CH}_{2} \mathrm{Cl}_{2}\right)$ is added to $671.141 \mathrm{~mL}$ of chloroform $\left(\mathrm{CHCl}_{3}\right)$ to prepare $2.6 \times 10^{-3} \mathrm{M}$ solution of $\mathrm{CH}_{2} \mathrm{Cl}_{2}(\mathrm{DCM})$ . The concentration of $\mathrm{DCM}$ is ___________ ppm (by mass).

Given :

atomic mass : C = 12

H = 1

Cl = 35.5

density of $\mathrm{CHCl}_{3}=1.49 \mathrm{~g} \mathrm{~cm}^{-3}$

Step-by-Step Verified Solution

Mass of $\mathrm{CHCl_3=671.141\times1.49=1000}$ gm

$2.6 \times {10^{ - 3}} = {{moles\,of\,C{H_2}C{l_2}} \over {0.671141}}$

$\Rightarrow$ moles of $C{H_2}C{l_2} = 1.74496 \times {10^{ - 3}}$

mass of $C{H_2}C{l_2} = 148.32 \times {10^{ - 3}}$ gm

Composition of $C{H_2}C{l_2} = {{148.32 \times {{10}^{ - 3}}} \over {1000}} \times {10^6}$

= 148.32 ppm

$\approx$ 148

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