Question

which of the equivalence point of phosphoric acid can you detect with higher accuracy? explain.

Answer 1

Phosphoric acid is a triprotic acid and the three titration of Phosphoric acid is as follows:

H₃PO₄ -----> H₂PO₄^- + H⁺

H₂PO₄ -----> HPO₄^2- + H⁺

HPO₄^2- -----> PO₄^3- + H⁺

As Phosphoric acid is a triprotic acid, it has three equivalence points but only the first two equivalence points, corresponding to base reaction with the first and second protons can be detected with higher accuracy. This is because only the first two equivalence points exhibit larger change in pH and the third equivalence point is obscured by the competitive ionization of water.