# When an acid is added to a buffer, does the acid in the buffer turn into base to neutralize the acid? Or is there some other that the buffers maintains constant pH?

$p H = p {K}_{a} + {\log}_{10} \left\{\frac{\left[{A}^{-}\right]}{\left[H A\right]}\right\}$...when a moderate quantity of ${H}_{3} {O}^{+}$ is added, the $\left[{A}^{-}\right]$ is REDUCED, given that it is protonated to give increased $\left[H A\right]$. But because the ratio is modified by the logarithmic term, the diminution in $p H$ is modified...and likewise if base is added...