Question

The Ka values of maleic acid, HOOCCHCHCOOH, are shown below.
Ka1 1.5 10-2
Ka2 2.6 10-7

A 50.0 mL sample of 0.11 M of maleic acid is titrated with 0.14 M NaOH. Calculate the pH at the following points in the titration curve.


find the first and second eq point pH


i thoguth i was doing it right but i cant get it

Answer 1

For the first equivalence point,
(H^+) = sqrt(k1k2)
For the second equivalence point, pH is determined by the hydrolysis of the salt, in this case Na2M
M^-2 + HOH ==> HM^- + OH^-
Write the Keq (Kb) expression, set up an ICE chart, solve for OH^-, convert to pOH, then to pH.