Acid-base reactions of compounds differ from redox reactions in that no change in oxidation number occurs.
Reactions of compounds with water, aqueous acid or aqueous alkali are examples of this reaction type.
The product of an acid-base reaction of a chloride ECln or an oxide ExOy depnds on the form which E in that oxidation state takes at the pH of the final solution.
| in acid | at pH 7 | in strong base | |
| MostGroup 1 and 2metal ions | Mn+(aq) | Mn+(aq) | Mn+(aq) |
| Beryllium ions(less metallic) | Be2+(aq) | Be(OH)2(s) | Be(OH)42–(aq) |
| Boron(III) (nonmetal) | B(OH)3(aq) | B(OH)3(aq) | B(OH)4–(aq) |
Hence while ionic chlorides like NaCl and MgCl2 dissolve in water to give their constituent hydrated ions, molecular chlorides (like BCl3) react with water and are not recovered from the solution if it is evaporated.
ECl3 + 3H2O
E(OH)n + 3HCl(aq)