SOLUBILITY RULES

Most of the precipitation reactions that we will deal with involve aqueous salt solutions. Remember salts are compounds which consist of metal cations like Na+, Ca2+, Cu2+ (or the one nonmetal molecular ion that we have discussed, ammonium - NH4+) ionically bonded to nonmetal anions such as Cl-, (including molecular anions such as hydroxide - OH-, sulfate - SO42-, phosphate - PO43-, nitrate - NO3-, and carbonate - CO32-), dissolved in water. Salts can be divided into two types: those soluble in water, and those insoluble in water. You should know some simple solubiity rules which will allow you to know which salts are soluble in water.

McMurry and Fay give two basic solubility rules:

  1. A compound is probably soluble if it contains one of the following cations:
  1. A compound is probably soluble if it contains one of the following anions:

Here is a more extensive set of solubility rules: