# How do you calculate buffer capacity?

Dec 7, 2014

A buffer solution will maintain a constant pH with the addition of small amounts of acid and alkali.

There is a limit to the amount of acid or alkali that the buffer can handle.

The buffer capacity is given by the expression:

$\frac{\mathrm{dn}}{d \left(p H\right)}$

$\mathrm{dn}$ is a tiny amount of added base which results in tiny change in pH shown as $d \left(p H\right)$

If you have a weak acid whose dissociation constant is ${K}_{a}$ then the buffer capacity is given by :

(From Wiki)

${C}_{A}$ is the concentration of the acid.