Question

Explain common ion effect with example.

Answer 1

Common ion effect. ... Some of the salt will be precipitated until the ion product is equal to the solubility product. In short, the common ion effect is the suppression of the degree of dissociation of a weak electrolyte containing a common ion. The Common Ion Effect. The solubility of insoluble substances can be decreased by the presence of a common ion. AgCl will be our example. AgCl is an ionic substance and, when a tiny bit of it dissolves in solution, it dissociates 100%, into silver ions (Ag+) and chloride ions (Cl¯).

Answer 2

$\textbf{\large{Answer -}}$

To the solution of weak electrolyte a salt solution having common ion is added then the dissociation of weak electrolyte is suppressed. This effect is known as $\textbf{common ion effect.}$

For Example :

In presence of $CH_{3}COONa$ , dissociation of $CH_{3}COOH$ is suppressed.

Explanation :

$CH_{3}COOH$ is weak electrolyte and are dissociated as follow -

$CH_{3}COOH (aq) ==> CH_{3}{COO}^{-} + {H}^{+}$

$CH_{3}COONa$ is a strong electrolyte and are dissociated as follow -

$CH_{3}COONa ==> CH_{3}{COO}^{-}+ {Na}^{+}$

Due to presence of common ion i.e., $CH_{3}{COO}^{-}$ ion, the concentration of $CH_{3}{COO}^{-}$in solution is increased and according to Le-Chatelier Principle, the equilibrium will shift in backward direction i.e., dissociation of acetic acid is suppressed.