Chemistry - Liquid Solution Question with Solution | TestHub

$\begin{array}{cccccccc}& \text{KI}\text{(aq)} & +& {\text{AgNO}}_{\text{<mn>3</mn>}}\text{(aq)}& ⟶& {\text{KNO}}_{\mathrm{3(}}\text{(aq)}& +& \text{AgI}\text{(s)}\\ \text{millimoles}& 30\times 0\text{.}1& & 10\times 0\text{.}2& & & & \\ & 3& & 2& & 0& & 0\\ \text{mm left}& 1& & 0& & 2& & 2\end{array}$

$\therefore$[KI] in solution$=\frac{1}{40}$and [KNO₃]$=\frac{2}{40}$&
(Assuming molarity = molality for dilute soluation)
$\therefore \text{Δ}{\text{T}}_{\text{f}}=\text{Δ}{\text{T}}_{\text{f}}(\text{b}\text{y}\text{K}\text{I})+\text{Δ}{\text{T}}_{\text{f}}(\text{b}\text{y}\text{K}\text{N}{\text{O}}_3)$
$=\text{molality}\times \text{1.86}\times {\text{i}}_{\text{KI}}+\text{molality}\times \text{1.86}\times {\text{i}}_{{\text{KNO}}_3}$
$=\left(\frac{1}{40}\times 1.86\times 2\right)+\left(\frac{2}{40}\times 1.86\times 2\right)$
$=0\text{.}093+0\text{.}186=0\text{.}27\mathrm{9\; =\; 0.28}°\text{C}$