# Molarity vs Normality in labeling sulfuric acid

Molarity (M) is defined as moles of solute per liter of solution while Normality (N) is defined as moles of reacting units per liter of solution. Most texts use sulfuric acid as an example to demonstrate the difference: a 1 M solution of sulfuric acid is 2 N because each mole of sulfuric acid gives two moles of $\ce{H+}$ (the "reacting unit"). Why then is concentrated sulfuric acid labeled as 18 N when it should be 18 M and 36 N (according to my text's example above)?

• Just for reference (and archiving), can you give an example of a label of "18 N" for sulfuric acid? – Geoff Hutchison Mar 10 '15 at 16:00