The molality of a 10% (v/v) solution of di-br | vedclass

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(B) $10\%\ (v/v)$ solution means $10\ mL$ of solute $(Br_2)$ is present in $100\ mL$ of total solution.Therefore,the volume of solvent $(CCl_4)$ $= 10

Vedclass · Accepted Answer

$139$

Vedclass · Answer

(B) $10\%\ (v/v)$ solution means $10\ mL$ of solute $(Br_2)$ is present in $100\ mL$ of total solution.Therefore,the volume of solvent $(CCl_4)$ $= 100\ mL - 10\ mL = 90\ mL$.Mass of solute $(Br_2)$ $= 	ext{Volume} 	imes 	ext{Density} = 10\ mL 	imes 3.2\ g\ cm^{-3} = 32\ g$.Mass of solvent $(CCl_4)$ $= 	ext{Volume} 	imes 	ext{Density} = 90\ mL 	imes 1.6\ g\ cm^{-3} = 144\ g = 0.144\ kg$.Moles of solute $(Br_2)$ $= \frac{32\ g}{160\ g\ mol^{-1}} = 0.2\ mol$.Molality $(m)$ $= \frac{	ext{moles of solute}}{	ext{mass of solvent in kg}} = \frac{0.2}{0.144} \approx 1.3888\ m$.Expressing as $x 	imes 10^{-2}\ m$,we get $138.88 	imes 10^{-2}\ m$.Rounding to the nearest integer,$x = 139$.

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