Question

A $42$ molal solution of sodium chloride in water causes an elevation in the boiling point of water by $1.88$K. What is the value of Van't Hoff factor? What does it signify? $[K_b=0.52K$ kg $mo{l}^{-1}]$.

Answer 1

Elevation in boiling point $\Delta T_b$ is a colligative property and $\Delta T_b=i\times K_b\times$ molality.
Given: $\Delta T_b=1.88K$.

$K_b=0.52Kkg$ $mo{l}^{-1}$

Molality $=2$ and i is Van't Hoff factor.

$\therefore i=\frac{1.88}{0.52\times 2}$

$i=1.8076$.
Value of 'i' in this case signifies that when $1$ mole of NaCl is dissolved in water it dissociates and furnishes $1.8076$ moles of particles in the solution.