# How do you calculate the pH of a buffer?

Jun 28, 2017

You need details of the acid used, and specific concentrations of acid and base from which it was composed.......

#### Explanation:

$p H = p {K}_{a} + {\log}_{10} \left\{\frac{\left[{A}^{-}\right]}{\left[H A\right]}\right\}$

And thus in equimolar quantities of weak acid and conjugate base, the $p H$ of the buffer is equal to the $p {K}_{a}$ of the weak acid. Why?