Question

Question #96889

Answer 1

See this old answer.

Explanation:

So simply take a weak acid, `HA`, and add approx 1/2 an equiv of sodium hydroxide solution. Alternatively, take the salt of a weak acid, `Na^+A^-`, and again add 1/2 an equiv of strong mineral acid. The `pH` of the solution will remain tolerably close to the `pK_a` of the starting acid.

Given the buffer equation:

`pH=pk_a+log_10{[[A^-]]/[[HA]]}`

you should be able to tell me why this is so.