What do buffers primarily resist changes in?

Buffers are solutions that can minimize changes in pH when small amounts of an acid or a base are added. They work by utilizing a weak acid and its conjugate base (or a weak base and its conjugate acid) to maintain a relatively stable hydrogen ion concentration. This stability in pH is crucial in many biological systems, as even minor fluctuations can significantly affect biochemical reactions and processes.

The reason why pH is the primary characteristic that buffers resist changing lies in their ability to either donate protons (H⁺) or absorb them, thereby counteracting any additions that would normally shift the pH. The effective range of a buffer is typically around the pKa of the weak acid or base it contains, making it particularly adept at maintaining a specific pH range.

In contrast, while concentration and pressure can be influenced by various factors in a solution, they are not the primary concern of a buffer system. Temperature also affects biochemical reactions but is not a direct variable that buffers are designed to address. Therefore, understanding the role of buffers in resisting changes in pH is essential in the study of biochemistry and physiological processes.