Does imidazole and hydrochloric acid yield imidazole hydrochloride salt? I'm asking this because I found a link for imidazole-HCl buffer: , but from what I understand, a buffer is a weak acid or base with its corresponding salt. Would imidazole-HCl buffer be a salt solution, or does it have a weak acid or base as well (if it does, what is the weak acid/base)? Also, I found two different pictures for imidazole hydrochloride:


Which one is correct? Is imidazole-HCl a salt or a buffer?
The correct structure of the salt is as shown above. This structure is more stable than the one that has two hydrogens on the same nitrogen - due to electron delocalization.

If you have a water solution of about 50/50 imidazole base and the hydrochloride salt, you get the maximum buffer capacity, due to the fact that both acid and base forms are present, and a small amount of a strong acid or base subsequently added to the mixture will react with these imidazole species, and therefore have little effect on the pH.