What Is a Titration Experiment & How Is It Carried Out?

Titration

• The aim of a titration procedure is to find the unknown concentration of a known reactant by reacting it with another reactant of already known concentration. Since the two substances interact with each other as they are being combined, at some point the entire volume of the reactant of unknown concentration is consumed in the reaction and this endpoint is signaled by visible or measurable changes in the reaction solution. At that point, since the precise volumes of both solutions used are now known, one can calculate the unknown concentration.

Titration Experiment

• In a titration procedure, the volumes of the two reactants are measured out. The reactant of known concentration is generally placed into a burette and the precise volume of the reactant of unknown concentration is placed into a beaker or Erlenmeyer flask underneath the burette. An indicator is also placed into the beaker or flask (or some other means is employed to measure the changes going on in the reaction solution). The reactant in the burette is then slowly added to the beaker or flask and the addition is stopped immediately when the the endpoint of the titration is reached.

Acid-Base Titration

• Titrations involving an acid and a base are very common. In these experiments, either an acid or base of unknown concentration is reacted with a base or acid, respectively, of known concentration. When the acid and base neutralize each other and the pH of the solution is in a narrow range, an indicator that is in the reaction solution changes color, signaling the endpoint of the titration. The precise point at which the endpoint occurs depends on how strong or weak the reacting acid and base are.

pH

• Acid-base titrations rely on pH measurements. The pH scale, which runs from 0 to 14, is a way of measuring how many hydronium ions are present in a solution. Solutions with a high concentration of hydronium ions are said to be acidic and have a pH below 7, while solutions with low concentrations of hydronium ions are said to be basic and have a pH above 7. Indicators used in acid-base titrations will exhibit a specific change in color over a narrow range of pH values.