What doesnt produce a buffer solution?

Question

say you have a weak acid and its conj. base, with HCl, does that not product a buffer solution?

Answer 1

Only a weak acid and its (strong) conjugate base will form a buffer - or a weak base and its strong conjugate acid. The whole buffer thing relies on the weak acid (or base) being pretty much un-ionised. If you were to use HCl, it is fully ionised and cannot form a buffer solution.