Question about buffers

Question

I have a hard time understanding the concept of buffers. I see in books it says the rule of thumb is pka should be +/- 1 pH unit from the ph of the reaction.

When would it be useful to prepare a buffer 0.5 pH units above its pka value?

Answer 1

Hmm, I'm not sure I understand your question and what the "rule of thumb" was in context to?

pKa is referring to the pH at which the dissociation rate is constant for either the weak acid or weak base into their conjugate forms. pH is scaled in a log, which means every increase in 1 pH is actually 10x the increase (difference of 2 pH is 100x, 3 pH is 1000...). Can you can see how logs are easier to calculate with whole numbers?