Titration is a common laboratory method of quantitative chemical analysis used to determine the unknown concentration of a known reactant. It typically involves the addition of an acid with a base, which, upon chemical reaction, produces a salt of some type and water. An indicator, such as phenolphtalein, is often used to indicate when the titration point has arrived. An example of such a titration would be adding sodium hydroxide to hydrochloric acid:
NaOH + HCl ---> NaCl + H2O (subscripts)
The volume used to achieve the necessary titration is critical in determining the concentration of the known reactant. If water is added to the known reactant before the titration occurs, it will have a weakening effect, a "watering down" of the known reactant. This will require less of the titrating reactant, and thus give an incorrect answer as to the concentration of the reactant being titrated. The extra volume must be taken into consideration, otherwise the results of the titration will be incorrect.