Buffer Capacity
The amount of strong acid or base a buffer can absorb before its pH changes appreciably.
Formula / equation
β = dn / d(pH)
Unit
mol/L
In depth
Capacity increases with the total concentration of the buffer components and is greatest when they are present in equal amounts, that is when the pH equals the pKa. Once one component is largely consumed, the buffer fails abruptly and the pH shifts sharply.
Examples in the real world
A 1.0 M acetate buffer resists change ten times better than an otherwise identical 0.1 M buffer.