When a diprotic acid, , is titrated with , the protons on the diprotic acid are generally removed one at a time, resulting in a pH curve that has the following generic shape: Notice that the plot has essentially two titration curves. If the first equivalence point occurs at 100.0 mL added, what volume of added corresponds to the second equivalence point? Volume = mL For the following volumes of added, list the major species present after the reacts completely.

At the second equivalent point 200 mL of NaOH is required.

Explanation:

at the first equivalent point:

                              H2A    +     OH-       =     HA-  +     H2O

initial mmoles        y*100         y*100            -                -

final mmoles            0                0                 y*100       y*100

at the second equivalent point:

                              HA-    +     OH-       =     A2-  +     H2O

initial mmoles        y*100         y*100            -                -

final mmoles            -                -                 y*100       y*100

at the second equivalent point we have that y*100 mmoles of NaOH or 100 mL of NaOH ir required, thus:

at the second equivalent point 200 mL of NaOH is required.