Question

The van't Hoff factor $\left(i\right)$ for a dilute aqueous solution of the strong electrolyte barium hydroxide is:

[NEET 2016]

Answer 1

$i=\frac{\text{Observed value}}{\text{Calculated value}}$

Observed value is the number of ions produced on dissolution and the calculated value is the number of ions before the dissolution.

The chemical formula of barium hydroxide is $Ba(OH{)}_2$. Barium hydroxide is a strong electrolyte that dissociates completely in water.

The dissolution of barium hydroxide is shown as follows:

$Ba\left(OH{)}_2\stackrel{H_{2}O}{\to }B{a}^{2+}\right(aq)+2O{H}^{-}(aq)$

The number of ions produced on dissolution is three, one is barium ion and two are hydroxide ions. The number of ions before dissolution is one.
$i=\frac{3}{1}=3$