2. normality (N) = equivalents of solute / dm³ solution
 
Normality is a useful concentration unit to use during neutralization reactions (titrations). One mole of hydrogen ions reacts with one mole of hydroxide ions to produce water. But that doesn't mean that one mole of any acid will neutralize one mole of any base. Chemists need a unit for the amount of acid (or base) that will give one mole of hydrogen (or hydroxide) ions.

One equivalent is the amount of an acid (or base) that will give one mole of hydrogen (or hydroxide) ions.

The numerical values of normality and molarity are equal for acids and bases that give 1 equivalent of H⁺ or OH ⁻ per mole.

For example, a solution containing 1 mole of NaOH / dm³ is 1M and 1N. However, a solution containing 1 mole of H₂SO₄ / dm³ is 1M, but it is 2N because it contains 2 equivalents of H⁺ per mole.