Molarity is the most commonly used measure of concentration. It is expressed as the number of moles of solute per liter of solution.

A 1 M solution of H

_{2}SO

_{4}contains 1 mole of H

_{2}SO

_{4}per liter of solution.

H

_{2}SO

_{4}dissociates into H

^{+}and SO

_{4}

^{-}ions in water. For every mole of H

_{2}SO

_{4}that dissociates in solution, 2 moles of H

^{+}and 1 mole of SO

_{4}

^{-}ions are formed. This is where normality is generally used.

Normality is a measure of concentration that is equal to the gram equivalent weight per liter of solution. Gram equivalent weight is a measure of the reactive capacitity of a molecule.

The solution's role in the reaction determines the solution's normality.

For acid reactions, a 1 M H

_{2}SO

_{4}solution will have a normality (N) of 2 N because 2 moles of H+ ions are present per liter of solution.

For sulfide precipitation reactions, where the SO

_{4}

^{-}ion is the important part, the same 1 M H

_{2}SO

_{4}solution will have a normality of 1 N.