Titration Curve Method

Titration is a technique used to check the concentration of an unknown solution. The solution of a known concentration is added through the burette to the volume of the solution of unknown concentration until the reaction is complete. An indicator is used as a signal at the end of the reaction, known as the endpoint. The analyte and titrant both form a pair of acid and base. These types of titrations are observed through the change in pH as titration progresses. A titration curve represents the graphical view of the pH of the solution during the process of titration.

Basic Terms

Here are some important terminologies before we study titration curves:

• Titrant: It means a known solution of a concentration added to a different solution and has to be determined.

• Analyte: It is the solution whose concentration has to be determined.

• Equivalence point: It is a point in the titration at which the titrants added are sufficient to neutralise the solution of the analyte.

In a strong-acid base of the titration, when both acid and base moles are equal, and the pH reaches the level of 7, the equivalence point is reached. On the other hand, in weak acid and a strong base of titration, the pH level is always greater than 7 at the equivalence point.

Relationship Between Titration Curve and Equivalence Point

Titration Curve in Case of a Strong Base and Strong Acid

At the beginning of titration, as we mix the base with the acid, the pH level rises at a slow rate. Nearest to the point of equivalence, the pH started increasing rapidly. If the titration is like a strong base acid, the pH at the equivalence point equals 7. The rate at which the pH changes will again move down.

The picture below shows a strong acid and a strong base of the titration curve:

The titration curve shows the pH that occurs during the titration of an acid with the base. The left figure shows the titration when the base is added to the acid to increase the pH level. On the right side, the acid is added to the base. In both cases, the equivalence point is touched when the moles of both base and acid are at equilibrium, and the pH level is 7.

Titration Curve in Case of a Weak Acid and Strong Base

A titration curve can also be obtained when the acid is strong, and the base is weak. The shape of the general titration is the same, but the only change that occurs will be in the equivalence point.

When the acid is weak and the base is strong, the pH level is always more than 7 at the equivalence point. In the case of a strong acid and weak base, the pH is always less than 7 at the equivalence point.

Conclusion

The titration curve is calculated to determine the concentration of an unknown solution when any known chemical is mixed with the solution. It is a non-expensive, valuable tool that represents the graphical view of the pH of the solution during the process of titration. 

The above article explores the relation between titration curves and equivalence points. The titration curve of a strong acid and base is always S-shaped on the graph. The pH level changes in every situation with the change in equivalence point.