What does the term normality refer to in the context of solutions?

The term normality specifically refers to the number of equivalents of a substance per liter of solution. It is a way to express concentration, particularly for solutions that participate in acid-base reactions or redox reactions. In this context, an equivalent is defined as the amount of substance that reacts with or provides one mole of hydrogen ions (H⁺) or one mole of electrons in a chemical reaction.

Normality is especially useful in titration calculations, where the stoichiometry of the reaction is crucial. For instance, when dealing with acids and bases, it's important to know how many active particles are in a solution since different acids and bases can dissociate into different numbers of hydrogen ions.

This specific focus on equivalents distinguishes normality from other concentration measures such as molarity, which is solely based on the number of moles of solute in a liter of solution.