Determination of alkalinity in the water sample: a theoretical approach

Determination of alkalinity of water sample is generally carried out experimentally by titration method using a proper indicator. In the literature, five different cases of possible alkalinities are reported based on the experimental data of acid titration of water sample using phenolphthalein and methyl orange. The reported data is the volume of acid consumption and the relationship between the alkalinity causing ions present in the water sample. However, no systematic approach is available in the literature to understand these experimentally reported volume of acid utilized for neutralization reaction. To make students understand the key features of the reported experimental data, a systematic approach is presented in this study. By using a simple mathematics and a theoretical explanation to the reported reactions taking place during acid titration of water sample, a supplementary document is developed. The theoretical concept in the form of supplementary information is introduced without altering any data reported in the literature or experimental procedure.