Analysis of acid mixture by titration

ABSTRACTFormic acid and acetic acid are very expensive acids. However they are frequently used inindustry. Because of that, they are mixed with cheaper acids on the market. In this study,formic acid and acetic acid were mixed with hydrochloric acid, nitric acid, sulfuric acid andperchloric acid to prepare the weak acid-strong acid mixtures together. On the other hand,potentiometric titration was applied with the sodium hydroxide which is a strong base. Therewere two end points, in the resulted titration curves. First one belongs to weak acid, secondone belongs to strong acid. The potentiometric titration was applied several times with aconjugate base of weak acid. As a result, just one curve was obtained and this curve onlybelongs to the strong acid.Potentiometric titrations were repeated with different indicator mixtures to understand thefake acid solution as if there was no potentiometre available. Bromophenol blue/dimethylyellow indicator mixtures were used in the titration. The data was examined to find the fakemixtures of weak acid-strong acid.It is easy to detect any fake acid mixture by observing potentiometric titration of acid mixturewith a conjugate base of weak acid or titration with a strong base and a given indicatormixture.Keywords: Formic acid, acetic acid, analysis of acid mixture, indicator mixture