Buffer solution

A buffer solution (also known as a buffered solution) is a solution that resists changes in pH when small amounts of an acid or base are added, or when the solution is diluted. Buffer solutions are used in many scientific and industrial processes, and are essential in biological systems to maintain stable pH levels.

Composition

A buffer solution is composed of a weak acid and its conjugate base, or a weak base and its conjugate acid. The acid and base components can be in the form of a salt, or they can be separate molecules. The most common buffer solutions are acetic acid (a weak acid) and sodium acetate (its conjugate base), and ammonia (a weak base) and ammonium chloride (its conjugate acid).

Mechanism

The buffering capacity of a solution is due to the presence of the weak acid and its conjugate base (or vice versa). When an acid is added to the solution, it reacts with the base component of the buffer, reducing the concentration of hydrogen ions and thus preventing a significant change in pH. Similarly, when a base is added, it reacts with the acid component, reducing the concentration of hydroxide ions and preventing a change in pH.

Applications

Buffer solutions are used in a wide range of applications. In biology, they are used to maintain stable pH levels in body fluids and cell cultures. In chemistry, they are used in titration experiments to determine the concentration of an unknown acid or base. In industry, they are used in processes such as fermentation, dyeing, and tanning.

See also

• Acid-base reaction theories
• pH scale
• Henderson-Hasselbalch equation

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  Buffer titration graph
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  Buffer capacity illustration
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  Citric acid speciation