Buffer Question

[superjerry12]

Hey, i'm confused with weak acid - strong base titrations (for example NaOH and CH3COOH).

How does a buffer form from this and how does it work?

[RuiAce]

A buffer can only be formed between a weak acid and its conjugate base (which is also weak).

NaOH and CH3COOH will certainly not form a buffer, because they aren't acid-base conjugates. In fact, NaOH will never form a buffer, because it is a strong base.

If you want a buffer, you should consider a mixture of CH3COOH and NaCH3COOH for example. Also note that the formation of a buffer in itself has nothing to do with the titration process.

Brief outline of what a buffer is

A buffer is essentially formed when relatively even concentrations of a weak acid and its conjugate base are mixed together. By having such a mixture, we develop an equilibrium system, that's special in that it's more "resistant" to small changes in pH.

What I mean by more "resistant" is this. After you mix an equal concentration of an acid with its conjugate base, you get this mixture with some unknown pH. Say you then added a small amount of HCl in it by accident. If you do, the pH will lower, but it will only lower by a tiny bit (i.e. not by much at all). This all happens as a result of LCP (we've increased the concentration of H+, so the system adapts to counteract this change by producing more OH-).

[superjerry12]

Thank you! That clears up my confusion greatly.