A 0.100 M oxalic acid, HO2CCO2H, solution is titrated with 0.100 M KOH. Calculate the pH when 25.00 mL of oxalic acid solution is titrated with 35.00 mL of NaOH. Ka1 = 5.4 × 10−2 and Ka2 = 5.42 × 10−5 for oxalic acid.