Question

what is common ion effect

Answer 1

The common ion effect is responsible. ... 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.

Answer 2

If an ionic equillibrium, AB= A+ +B- , a salt containing a common ion is added , the equllibrium is shift in the backward direction. this is called common ion effect .