Ask A Scientist Chemistry Archive

Question:
Pertaining to the Bronsted Lowry definition of acids and bases,
how come the strength of a conjugate acid or base is inversely
proprtional to the strength of the other acid/base?

It seems that the more willing a acid or base is to give up/accept
a proton, the more willing its conjugate should accept/let go of one.
 mwang

Answer:
Think of it this way:  If strong and weak are competing, the strong one
will always win.  A strong conjugate base will always attract a proton.
A strong conjugate acid will always leave its weak base.  There's nothing
the weak species can do about it.  Cl- is a weak base.  It can't hold onto
it's proton so HCl will always completely dissociate.  CH3COO- (acetate
ion) is a strong conjugate base.  It doesn't want to give up the proton
and the proton can't do anything about it.  So acetic acid doesn't totally
dissociate.  Any clearer?
-Joe Schultz