Why does the OH react with HA and not H3O+?

[motornoob101]

In titrating HA, the weak acid with a strong base, why does the OH- ions from the strong base react with the HA atom (and neutralize it) rather than say react with the H3O+ to form complete neutralization? Just curious. Thanks.

 

[GCT]

HA donates protons to water regardless of whether the base is present or not however the hydroxide can neutralize the remaining HA molecules. Ultimately hydroxide is going to prefer the latter over the former.

 

[kalery]

In titrating HA, the weak acid with a strong base, why does the OH- ions from the strong base react with the HA atom (and neutralize it) rather than say react with the H3O+ to form complete neutralization? Just curious.
Thanks.

Hydroxide deprotonates weak acids and hydronium ion alike. In a basic solution, hydroxide abstracts acidic protons from both molecules.