A mixture of metal ions in a solution can be separated by precipitation with anions such as Cl-, Br-, SO42-, CO32-, S2-, Cr2O42-, PO42-, OH- etc. When a metal ion or a group of metal ions form insoluble salts with a particular anion, they can be separated form others by precipitation. We can also separate the anions by precipitating them with appropriate metal ions.
There is no definite dividing lines between insoluble salts, sparingly soluble, and soluble salts, but concentrations of their saturated solutions are small, medium, and large. Solubility products are usually listed for insoluble and sparingly soluble salts, but they are not given for soluble salts. Solubility products for soluble salts are very large.x