Making a buffer solution

[4dhayman]

I was wonder how I might go about making a buffer solution.

I plan to choose an acid and conjugate base (or vice versa) for my chosen pH using the Henderson-Hasselbach equation. But, let's say I choose acetic acid. Should I just pour some acetic acid into a volume of water and let equilibrium arise on its own? Will this produce a buffer?

Also, if I were to graph changes in pH over time and I add some acid to the buffer, will the buffer pH simply not change much, or will it exhibit damped motion around the target pH.

Thanks in advance.

[Borek]

If you use just some acetic aid, you will not have a buffer - for that you need also a conjugated base. So you have to add either some strong base (like NaOH) to neutralize part of the acid, or salt (like sodium acetate) to enter requested amount of conjugated base.

After you add acid or base to buffer solution it will react with buffer components (acid or conjugated base) and the new pH will be again given by Henderson-Hasselbalch equation.

Note: this is rather chemistry question.

Borek
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Buffer Maker - the ultimate buffer calculator (http://www.chembuddy.com/?left=Buffer-Maker&right=buffer-calculator)

[4dhayman]

But, excuse my ignorance, doesn't the conjugate base have to be the conjugate of the acid used, so the acetic acid buffer would require acetate ions?

Sorry for misplacing this topic.

[Borek]

You need acetic acid/acetate pair, but that's not a problem - if you add strong base, acetic acid gets neutralized and becomes acetate, when you add strong acid, acetate gets protonated and becomes acetic acid.

Borek
--
Buffer Maker - the ultimate buffer calculator (http://www.chembuddy.com/?left=Buffer-Maker&right=buffer-calculator)