Solutions and Colligative Properties - Result Question 60
####31. To $500 cm^{3}$ of water, $3.0 \times 10^{-3} kg$ of acetic acid is added. If $23 %$ of acetic acid is dissociated, what will be the depression in freezing point? $K _f$ and density of water are $1.86 K kg^{-1} mol^{-1}$ and $0.997 g cm^{-3}$, respectively.
$(2000,3 M)$
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Solution:
- Mass of water $=500 \times 0.997 g=498.5 g$
$$ \begin{aligned} & \text { Also } \underset{1-\alpha}{CH _3 COOH} \underset{\alpha}{\rightleftharpoons} CH _3 COO^{-}+\underset{\alpha}{H^{+}} \ & \Rightarrow \quad i=1+\alpha=1.23 \ & \Rightarrow \quad-\Delta T _f=i K _f \cdot m=1.23 \times 1.86 \times \frac{3}{60} \times \frac{1000}{498.5}=0.23^{\circ} C \end{aligned} $$
