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(B) $1$. Calculate the molar mass of acetic acid $(CH_3COOH)$: $12 + 3(1) + 12 + 16 + 16 + 1 = 60 \ g \ mol^{-1}$.$2$. Calculate the van't Hoff factor

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$372$

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(B) $1$. Calculate the molar mass of acetic acid $(CH_3COOH)$: $12 + 3(1) + 12 + 16 + 16 + 1 = 60 \ g \ mol^{-1}$.$2$. Calculate the van't Hoff factor $(i)$ for $20\%$ dissociation $(\alpha = 0.2)$: $i = 1 + \alpha(n-1) = 1 + 0.2(2-1) = 1.2$.$3$. Calculate the molality $(m)$ of the solution: $m = \frac{	ext{moles of solute}}{	ext{mass of solvent in kg}} = \frac{5/60}{0.5} = \frac{1}{6} 	imes 2 = 0.333 \ mol \ kg^{-1}$.$4$. Calculate the depression in freezing point $(\Delta T_f)$: $\Delta T_f = i 	imes K_f 	imes m = 1.2 	imes 1.86 	imes \frac{5 	imes 1000}{60 	imes 500} = 1.2 	imes 1.86 	imes 0.1666 = 0.372 \ { }^{\circ}C$.$5$. Express in the required format: $0.372 \ { }^{\circ}C = 372 	imes 10^{-3} \ { }^{\circ}C$.

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