What are the limitations of acid-base titrations?

Acid-base titrations have limitations such as inaccuracies in endpoint determination, indicator selection, and measurement errors.

Acid-base titrations are a common method used in chemistry to determine the concentration of an unknown solution. However, they do have several limitations that can affect the accuracy of the results. One of the main limitations is the difficulty in accurately determining the endpoint of the titration. The endpoint is the point at which the reaction between the acid and base is complete. It is usually determined by a colour change in an indicator, but this can be subjective and may vary slightly between different observers.

Another limitation is the selection of the indicator. The indicator must change colour at the exact pH at which the reaction is complete. However, different indicators change colour at different pH levels, so the choice of indicator can significantly affect the results. If the wrong indicator is chosen, the endpoint may be determined incorrectly, leading to inaccurate results.

Measurement errors can also limit the accuracy of acid-base titrations. These can occur when measuring the volumes of the solutions, or when reading the burette. For example, if the initial and final readings on the burette are not recorded accurately, this can lead to errors in the calculated concentration of the unknown solution.

Furthermore, the purity and stability of the solutions used can also affect the results. If the solutions are not pure or if they have degraded over time, this can lead to inaccuracies in the titration. Similarly, if the solutions are not mixed thoroughly during the titration, this can also lead to errors.

IGCSE Chemistry Tutor Summary: Acid-base titrations have several limitations that can impact their accuracy, including challenges in pinpointing the exact endpoint, selecting the appropriate indicator, and avoiding measurement errors. The process demands careful attention to detail, as the choice of indicator, accuracy in measuring solution volumes, and ensuring solution purity and thorough mixing are crucial to obtaining reliable results.