THE IMPORTANCE OF TEACHING TITRATION CURVES IN ANALYTICAL CHEMISTRY

Abstract

Titration curves are an essential subject of an Analytical Chemistry course. The main objective of calculating titration curves is the selection of an indicator for such titrations. The calculation of titration errors is imperative because they establish if a given indicator can be used for a given titration. This study reviews the available literature on titration curves and calculating their errors. Its purpose is to draw attention to the importance of undergraduate chemistry students having competencies to determine the titration errors rather than skills to build titration curves as the ultimate purpose of these curves is to determine the failure committed when using a given indicator to assess their endpoints. It is shown that the pH and potential calculation at the equivalence point in acid-base and redox titrations, respectively, are not required to choose the titration indicator, one that yields an acceptable error according to the type of application needed. Methods to calculate these errors in the four main types of titrations are presented; those for complexometric and precipitation titrations are simpler than in the literature. Here, it is also demonstrated that calculating points immediately after and before the curve inflection are more critical for this selection in these two types of titrations. Also, it is deducted that complexometric and precipitation curves are not required to select indicators for these titrations. These demonstrations are essential because analytical chemistry teachers may disregard teaching important topics by spending time calculating unnecessary titration curves (complexometric and precipitation titrations) or additional points of titration curves (redox and acid-base titrations) when the calculation of titration errors of these reactions is more critical. Most analytical chemistry textbooks neglect this topic. Undergraduate chemistry programs should focus more on calculating titration errors than on the construction of titration curves.