25 mL of an aqueous solution of KCl was found to require 20 mL of 1 M $\mathrm{AgNO_3}$ solution when titrated using $\mathrm{K_2CrO_4}$ as an indicator. What is the depression in freezing point of KCl solution of the given concentration? _________ (Nearest integer).
(Given : $\mathrm{K_f=2.0~K~kg~mol^{-1}}$)
Assume 1) 100% ionization and 2) density of the aqueous solution as 1 g mL$^{-1}$
Answer (integer)
3
Solution
$25 \times M=20 \times 1$
<br/><br/>$$
\begin{aligned}
M & =\frac{20}{25}=\frac{4}{5}=0.8 \\\\
\Delta T_{f} & =(\mathrm{i})\left(\mathrm{K}_{\mathrm{f}}\right)(\mathrm{m}) \\\\
& =(2)(2)\left(\frac{4}{5}\right)=\frac{16}{5}=3.2
\end{aligned}
$$
About this question
Subject: Chemistry · Chapter: States of Matter · Topic: Gas Laws
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