[Traumatic Acid]

Hiya!
I've always been confused as to when a base is protonated / deprotonated in relation to it's pKa. An acid will deprotonate when the pH of the solution approaches / exceeds the pKa of the acid in question. pH < pKa = Protonated. Does this also stand true for bases? Because at a pH lower than the pKa of an acid the high number of H+ ions makes deprotonation unfavourable. However for a base wouldn't a lower pH make deprotonation favourable? Apparently not. Can anyone explain why this is?  Does a higher concentration of H+ ions make the donation of OH- unfavourable?

Thanks for any input

[Borek]

Think in terms of Brønsted-Lowry's theory, it describes the reaction with the proton and allows identical treatment of both acids and bases.

[Traumatic Acid]

Think in terms of Brønsted-Lowry's theory, it describes the reaction with the proton and allows identical treatment of both acids and bases.

Righto, so when the pH of a solution reaches near / exceeds that of the base pKa it stops accepting the H cations and begins donating OH anions to the solution?

[Borek]

Well, in Brønsted-Lowry's theory it is not like it "donates" OH^-, more like OH^- is a byproduct of stealing H⁺ from water molecules. Not that it matters when you are trying to determine whether the substance is protonated or not. Given pKb you can always easily convert it to pKa, and then finding out protonation status is identical to that used for acids.