The figure shown below shows a typical titration curve for 0.1 M NaOH with 40 mL of 0.05M oxalic acid (H2C2O4). The first equivalent point is ~ at 9 .0 mL and the second equivalent point is at ~18 mL.
(a) Determine pka1, pka2, pkb1 and pkb2
(b) Calculate the pH at points labeled A, B, C, D, and E