Titration, also known as “volumetric analysis”, is a common laboratory process performed to acquire information that allows you to calculate the molar concentration of a solution with an unkown concentration.
Titration involves 3 basic things: a reagent or liquid of known concentration called the titrant, the liquid of unknown concentration called the titrand, and a calibrated device for delivering the titrant in a precise volume into the titrand such as a burette. The titrant and titrand should be in liquid form. If not, they are dissolved. The titrant also functions as the indicator. A clean beaker or Erlenmeyer flask is also needed to contain the titrand. For more conveniences, a burette stand may be used.
Titration begins with a beaker or flask containing a precise volume of the titrand placed underneath a burette containing the titrant. Before proceeding, the initial volume in the burette must be recorded. After this, the burette is used to add the titrant to the titrand to within a couple of milliliters of your expected endpoint. You will see the indicator change color when the titrant hits the solution in the flask, but the color change disappears upon stirring or shaking. Add the titrant drop by drop until you reach the endpoint or when the color change persists slightly even if it is stirred or shook. When you have reached the endpoint, record the final volume in the burette.
Subtract the initial volume from the final volume in the burette to determine the amount of titrant delivered. Using the amount of titrant delivered, the concentration of the titrant, and the stoichiometry of the titration reaction, it’s possible to calculate the number of moles of reactant in the titrand. By dividing the number of moles of reactant by its volume, the concentration can then be calculated thus fulfilling the purpose of titration.
The endpoint is noted by an indicator through a visual signal by means of a color change. This happens because excess unreacted molecules needed to reach the endpoint reacts with the indicator molecules thus changing the structure of the indicator molecule so that its color changes. An indicator must not be confused with an endpoint because an indicator signals the completion of titration while the endpoint is the completion of titration itself.