Sections 16.6 - 16.7: Buffer Solutions

Buffer solutions have the ability to resist changes in pH upon addition of small amounts of either acid or base.

Buffers are very important in chemical and physiological processes. The pH in the human body varies from one fluid to another. For example, the pH of blood is 7.4, whereas the pH of gastric juices in the stomach is about 1.5. Blood can absorb the acids and bases produced in biological reactions without changing its pH. Thus, blood is a buffer solution.

A buffer solution consists of a weak acid and its salt or a weak base and its salt. In other words, a buffer solution follows the concepts of common ion solutions.

An example of an acidic buffer solution is a mixed solution of the weak acid, HF, and its salt, NaF. Similarly, an example of a basic buffer solution is a mixed solution of the weak base, NH₃, and its salt, NH₄Cl. By choosing appropriate solutes and concentrations, a buffer solution can be created for any desired pH.