Normality:

A normal concentration is another method for expressing the concentration of solutions. The Normality (N) is described as the number of equivalent of solute dissolved within one liter of solution.

Normality (N) = equivalent of solute / liter of solutions

One equivalent of acid is the amount of acid essential to provide up one mole of hydrogen ions within a chemical reaction. A single equivalency of base is the amount of base which reacts along with one mole of hydrogen ions. While expressing the concentrations of bases, normality denoted to the number of available hydroxyl ions. Since hydrogen and hydroxyl ions merge on a one-to-one basis, one OH- is equal to one H⁺ ion.

a)    H⁺Cl^-       +          Na⁺OH^-    →   Na⁺Cl^-             +          H⁺OH^-

        Acid                    base                   Salt                           Water

b)    H₂SO₄      +          2K⁺OH^-    →   K₂SO₄             +          2H⁺OH^-

        Acid                    base                   Salt                           Water

Remember that in reaction a), one mole of HCl yields one equal per mole or one mole of H⁺ ions. The H₂SO₄ has two equivalents per mole or two H⁺ ions since every mole of the compound could release two moles of hydrogen ions.

The number of equivalent of an acid or base could be determined from equivalent weight.  An equivalent weight is described as the molecular weight of the acid or base divided through the number of replaceable hydrogen or hydroxyl ions.