Question

$1$ molal aqueous solution of an electrolyte $A_{2}B_{3}$ is $60\%$ ionised. The boiling point of the solution at $1atm$ is _____ K. (Rounded-off to the nearest integer) [Given $K_{b}$ for $\left(H_{2} O\right)=0.52Kkg\left(mol\right)^{- 1}$ ]

Answer 1

$A_{2}B_{3} \rightarrow 2A^{+ 3}+3B^{- 2}$
No. of ions $=2+3=5$
$i=1+\left(\right.n-1\left.\right) \propto $
$=1+\left(\right.5-1\left.\right)\times 0.6$
$=1+4\times 0.6=1+2.4=3.4$
$ΔT_{b}=K_{b}\times m\times i$
$=0.52\times 1\times 3.4=1.768^\circ C$
$\left(ΔT\right)_{b}=\left(T_{b}\right)_{\text{solution }}-\left(\left[\left(T_{b}\right)_{H_{2} O}\right]\right)_{\text{Solution }}$
$1.768=\left(T_{b}\right)_{\text{solution }}-100$
$\left(T_{b}\right)_{\text{solution }}=101.768^\circ C$
$=375K$