In a buffering region, which of the following is true regarding the pH and pKa relationship?

In a buffering region, the relationship between pH and pKa is most accurately described by the notion that the pH is typically within 1 pH unit of the pKa value. This principle stems from the Henderson-Hasselbalch equation, which demonstrates that when a weak acid and its conjugate base are present, the solution can effectively resist changes in pH.

When the pH of a buffer solution is equal to the pKa of the weak acid involved, the concentrations of the acid and its conjugate base are equal. As a result, the buffering capacity is highest when the pH is within 1 unit of the pKa, which enables the system to minimize significant fluctuations in pH upon the addition of small amounts of acids or bases.

In contrast, a pH that is significantly lower than the pKa would indicate that the acid is predominantly in its protonated form, hence not in an optimal buffering capacity. Similarly, the endpoint of a titration curve is characterized by a sharp change in pH and does not represent the buffering region, while a rapid increase in pH would signify that the system is no longer functioning effectively as a buffer. Thus, being within 1 pH unit of the p