At T K xg of a non-volatile solid (molar mass 78 g mol - 1 ) when added to 0 . 5 kg water, lowered its freezing point by 1 . 0 ° C . What is x (in g ) ( K f of water at T ( K ) = 1 . 86 KKgmol - 1 )

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Aicharya · Accepted Answer

$\begin{aligned} &\begin{aligned} \Delta T_f & =k_f{}^* \text { molality } \ \text {Weight } & =x g \ \text {Mwt } & =78 \text { g } \ \text {Molality } & =\text { moles present in 1kg solvent } \ & =(x / 78) / 0.5 \ & =\frac{x}{39} \end{aligned}\ &\begin{aligned} \Delta T_f & =k_f{ }^* \text { molality } \ 1 & =1.86 \times \frac{x}{39} \ x & =\frac{39}{1.86} \ x & =20.96 \mathrm{~g} . \end{aligned} \end{aligned}$ *

At T K xg of a non-volatile solid (molar mass 78 g mol - 1 ) when added to 0 . 5 kg water, lowered its…

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