Calculate the pH for the following case in the titration of

Calculate the pH for the following case in the titration of 25.0 mL of 0.220 M pyridine, C5H5N(aq) with 0.220 M HBr(aq): a) after addition of 23ml HBr

Solution

mmoles of pyridine = 25 x 0.220 = 5.50

mmoles of HBr = 23 x 0.220 = 5.06

C5H5N   +   HBr    -------------> C5H5NHBr

5.50          5.06                            0

0.44             0                            5.06

pOH = pKb + log [salt / base]

      = 8.77 + log [5.06 / 0.44]

pOH = 9.83

pH = 4.17