- A buffer is most effective when the concentrations of salt and acid are equal:
- Corresponds to the pKa value of the buffer being closest to the desired pH value
- Has an effective range when 1 pH unit higher or lower than pKa
- This can be explained by the Henderson-Hasselbach equation:
- The buffer solution will have greatest capacity when the concentration of the acid and the conjugate base equal each other
- When this is the case, their concentration ratio equals 1
- Therefore the log is zero and so pH = pKa
