When a diprotic acid, H2A, is titrated by NaOH, the protons on the diprotic acid are generally removed one at a time, resulting in a pH curve that has the following generic shape.

Question

(a) Notice that the plot has essentially two titration curves. If the first equivalence point occurs at 100.0 mL of NaOH added, what volume of NaOH added corresponds to the second equivalence point?

Answer 1

If it takes 100 mL to remove the first H ion it will take another 100 mL to remove the second one (for a total of 200 mL to remove both). So the first equivalence point is at 100.0 mL and the second equivalence point is at 200.0 mL.

Answer 2

Thank you!