# What is buffering capacity? How is buffering capacity measured?

May 31, 2018

Well, what is the buffer equation....?

#### Explanation:

The buffer equation, derived here holds that....

${\underbrace{- {\log}_{10} \left[{H}_{3} {O}^{+}\right]}}_{p H} = {\underbrace{- {\log}_{10} {K}_{a}}}_{p {K}_{a}} + {\log}_{10} \left\{\frac{\left[{A}^{-}\right]}{\left[H A \left(a q\right)\right]}\right\}$

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

Buffering capacity thus DEPENDS on $\left[{A}^{-}\right]$ or $\left[H A\right]$...which of course is established when the buffer is prepared. The buffer continues to function UNTIL EITHER acid or base has been reduced to negligible concentration.... Given the equation, the $p H$ of a buffered solution remains tolerably close to the $p {K}_{a}$ of the acid used to prepare the buffer.