What is the role of a buffer solution?

A buffer solution plays a crucial role in maintaining a relatively constant pH in a solution, even when small amounts of an acid or base are added. This stability is vital in many biological and chemical processes where a specific pH is required for optimal function. Buffers generally consist of a weak acid and its conjugate base or a weak base and its conjugate acid. When an acid is added to a buffered solution, the base component of the buffer will neutralize the excess hydrogen ions (H+), while adding a base will lead to the weak acid component reacting with the hydroxide ions (OH-). This interaction minimizes fluctuations in the pH level, allowing the solution to resist significant changes despite the addition of acidic or basic substances.

The other choices do not accurately describe the primary function of a buffer. While some buffers can enhance solubility to a certain extent, their main purpose is to stabilize pH. Buffers do not neutralize all acids present or dilute the solution; instead, they work to mitigate changes caused by additional acids or bases, preserving the desired pH for reactions and processes.