Question

1 molal aqueous solution of an electrolyte $A_2{B}_3$ is 60% ionised . The boiling point of the solution at 1 atm in K is ( Rounded -off to the nearest integer )

$[K_{b}for\left(H_{2}O\right)=0.53Kmo{l}^{-1}]$

• A. 375.0
• B. 375.00
• C. 375

Answer 1

Answer: (A), (B), (C)

( Assuming A - cation , B - anion )
$A_2{B}_3\to 2A^{3+}+3B^{2-}1-0.62\times 0.63\times 0.6$

$\therefore \text{van't Hoff factor}=1-0.6+1.2+1.8=3.4$

$\Delta T_b=i\times K_b\times m$

$\Delta T_b=3.4\times 0.52\times 1=1.768$

$T_b-373=1.768$

$T_b=374.77\approx 375\left(\text{Nearest integer}\right)$