How do you interpret a titration curve?

A titration curve is interpreted by identifying its equivalence point, end point, and analysing the pH changes throughout the titration.

A titration curve is a graphical representation of the pH of a solution as a function of the volume of the added titrant. It is used to determine the concentration of an unknown solution (analyte) by adding a solution of known concentration (titrant) until the reaction between the two is complete. This is known as the equivalence point, which is the point at which the amount of titrant added is just enough to completely neutralise the analyte.

The equivalence point is usually indicated by a sharp change in the pH of the solution, which is represented by a vertical section on the titration curve. The pH at the equivalence point depends on the nature of the acids and bases involved in the titration. For a strong acid-strong base titration, the pH at the equivalence point will be 7. For a weak acid-strong base titration, the pH will be greater than 7, and for a strong acid-weak base titration, the pH will be less than 7.

The end point of a titration is the point at which the indicator changes colour. This is ideally the same as the equivalence point, but in practice, there may be a slight difference due to the properties of the indicator used.

The initial and final parts of the titration curve, where the pH changes gradually, represent the buffering regions. In these regions, the solution resists changes in pH when small amounts of acid or base are added. The midpoint of the buffering region, where the pH equals the pKa (for an acid) or pKb (for a base), is the point of maximum buffering capacity.

By interpreting a titration curve, you can determine the pKa or pKb of a weak acid or base, the equivalence point, and the end point of a titration, and understand the buffering capacity of a solution.