Which method is used to determine the concentration of an acid or base?

Titration is a quantitative analytical method used to determine the concentration of an acid or base in a solution. In this process, a solution of known concentration, known as the titrant, is gradually added to the solution of unknown concentration until a reaction reaches its endpoint, which is often indicated by a color change. This endpoint can be identified using pH indicators or pH meters, allowing the precise amount of titrant needed to neutralize the acid or base to be measured. The volume of titrant used, combined with its known concentration, is then calculated to determine the concentration of the unknown solution.

Other methods listed, such as evaporation, filtration, and distillation, do not directly provide information about the concentration of an acid or base in the same way titration does. Evaporation involves removing a solvent from a solution, which alters concentration but does not measure it directly. Filtration is used to separate solid particles from liquids or gases, and distillation separates components based on differing boiling points, neither of which measures the concentration of an acid or base directly.