Acid Base Titration - Titration Curves, Equivalence Point & Indicators of Acid Base Titration

Acid base titration is a process or method to determine the concentration of an acid or base by neutralising it with the solution of an acid or base which is having known concentration. It is an experimental technique to determine the concentration of an acid or base in a solution. In this titration, the endpoint is detected with the help of an indicator. In this process, acid is titrated with base and vice versa. In this titration process, we use two names such as titrant and titrate. Here titrant is the solution with unknown molarity and the titrant is the solution with known molarity and it reacts with the titrant.

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Here the concentration of the solution can be determined if the acid dissociation constant or base dissociation constant is known. Titration can also be used to determine the acidic or basic properties. Titration is a term derived from the Latin word ”titulus” which means a title. Titration can be defined as the process of adding the solution through the burette. Here the substance or component that is to be determined is titrated.

Key terms

The key terms involved in the acid-base titration are:

• Titration: It is the process in which the solution of known concentration is added to a solution of unknown strength containing an indicator.

• Titrant: It is the solution of known strength of concentration used in the titration process.

• Titrand: It is the solution to which the titrant is added and it contains ions that are to be determined.

• Titration curve: It is a graph between PH(Potential of Hydrogen and titrant in millilitres and it shows the way in which PH(Potential of Hydrogen) values change with respect to the titrant during the titration process.

• Equivalence point: It is the point at which the reagent is added for the complete reaction with a substance.

• Buffer solution: The solution that prevents the change in the value of PH(Potential of Hydrogen) when a strong acid or strong base or water is added.

Titration curve and Equivalence point

As the titration curve is the graph plotted between the titrant and the PH (Potential of Hydrogen) values. Here the PH value does not change in a regular fashion when the acid is added to the solution. In the curves, there are many horizontal sections and there is no large change in PH value even when the bases are added. And also there are steep positions when the weak acid or weak bases are added and at this point addition of even a single drop of acid or base leads to the larger change in the PH values. And at the equivalence point, the PH value is having a large change and this is based on the type of indicator used. Based on the type of titration the titration curve may vary accordingly.

The equivalence point is the point at which the same number of moles of hydroxide ions are added as that of the number of hydrogen ions. In this process of acid-base titration if a base is added from a burette then the acid is measured into a flask.