In case of a calcium chloride solution, if we increase the concentration of chloride ion.More of calcium chloride will be precipitated.If the concentration of chlorine is reduced, more of the salt gets dissolved. When hydrochloric acid is added to the saturated solution of sodium chloride. Sodium chloride is precipitated out, from the addition of chloride ions, which is a common ion. Sodium chloride thus obtained is of high purity. Hence, the common ion effect is used in quantitative estimation of salts.