You have a 100.0 ml of a 1.0 Formal concentration buffer solution that has 2 ionizable groups
(pKa 1 = 6.2 and pKa 2 = 9.5). The solution has a pH of 6.8. If you add 60 mL of 1.0 M HCl what would this change the pH too?
i think Pka 1 = 6.2 we are interested in because it close to pH of 6.8, but if u add strong acid like HCl, the pH should go down.