Explanation

The pH of a buffer solution depends on the concentration of both the acid (H+) and its conjugate base (-OH-). A buffer solution is a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. The pH of the solution is determined by the ratio of the concentrations of the acid and its conjugate base, as described by the Henderson-Hasselbalch equation: pH = pKa + log([base]/[acid])

Where:

• pH is the negative logarithm of the hydrogen ion concentration
• pKa is the acid dissociation constant
• [base] is the concentration of the conjugate base
• [acid] is the concentration of the acid

Therefore, the pH of a buffer solution depends on the concentration of both the acid (H+) and its conjugate base (-OH-).