[jjc]

Hi, I'd like some help with this concept.

Ascorbic acid is a dibasic acid. So we're given two values for acid dissociation constant as the neutralisation with NaOH undergoes 2 steps. Given the concentration of ascorbic acid, how do we find the initial pH of ascorbic acid? do we use Ka₁? Ka₂? or add both together?

[Borek]

General case, not easy:

http://www.chembuddy.com/?left=pH-calculation&right=pH-polyprotic-acid-base

Less general case, easier:

http://www.chembuddy.com/?left=pH-calculation&right=pH-polyprotic-simplified