Neutralization reactions involve the reaction of an acid plus a base produces salt and water.

Acid + Base --> Salt + Water

A monoprotic acid can furnish one proton, a diprotic acid two protons and a triprotic acid three protons to a neutralization reaction.

HCl + NaOH --> NaCl + H₂O

H₂SO₄ + 2NaOH --> Na₂SO₄ + 2H₂O

H₃PO₄ + 3NaOH --> Na₃PO₄ + 3H₂O

Neutralization of an acid means that all the acid has reacted with a base, and there are no more protons that can be furnished to additional base. The exact amount of base needed for neutralization will not necessarily produce a neutral solution. The final pH depends upon the nature of the salt that is produced. Some salts form neutral aqueous solutions, while others are either acidic or basic. There are four categories of neutralization reactions based upon the strength of the acid and strength of the base used in the reaction.