Question

define common ion effect. how does it effect the solubility of electrolytes.

Answer 1

In common ion effect, the soluble compound and the solution has one common ion. As a result of common ion, there is reduction in the solubility of an ionic precipitate owing to Le Chatelier's principle when the concentration of any one constituent is in excess, the reaction moves in the direction which undoes it. So, the reaction will move in the backward direction to reduce the concentration of the common ion.

So, it suppresses the dissociation of a weal electrolyte which contains a common ion and hence it decreases the solubility.