What is a buffer solution?

A buffer solution is defined as a solution that resists significant changes in pH when small amounts of acid or base are added. This characteristic is vital in many chemical and biological processes where maintaining a stable pH is essential for function. Buffers achieve this through a combination of a weak acid and its conjugate base, or a weak base and its conjugate acid. When an acid is added to the solution, the weak base component of the buffer can neutralize that added acid, while the weak acid can neutralize added bases. This ability to stabilize the pH makes buffers crucial in applications such as biochemical reactions, maintaining homeostasis in biological systems, and various industrial processes.

The other options represent concepts that do not align with the definition of a buffer. A solution that changes color with pH changes refers to indicators rather than buffers. Elimination of all impurities describes a purified solution instead of a buffer's pH-resisting properties. Lastly, while some buffer solutions can conduct electricity due to the ions present, conductivity is not an inherent property of buffer solutions specifically, and it does not define their function or purpose.