Buffer Solution

 A buffer solution is a solution that resists changes in pH when small amounts of acid or base are added to it. It is a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. Buffer solutions are used in a variety of applications, including:

 * Chemical reactions: Buffer solutions are used to maintain a constant pH during chemical reactions.

 * Biological systems: Buffer solutions are used to maintain the pH of blood and other bodily fluids.

 * Industrial processes: Buffer solutions are used in a variety of industrial processes, such as food production and wastewater treatment.

Here are some examples of buffer solutions:

 * A mixture of acetic acid and sodium acetate

 * A mixture of ammonium chloride and ammonia

 * A mixture of citric acid and sodium citrate

The pH of a buffer solution can be calculated using the Henderson-Hasselbalch equation:

pH = pKa + log([A-]/[HA])

where:

 * pKa is the negative logarithm of the acid dissociation constant of the weak acid

 * [A-] is the concentration of the conjugate base

 * [HA] is the concentration of the weak acid

Buffer solutions have a limited capacity to resist changes in pH. The buffer capacity is the amount of acid or base that can be added to a buffer solution before the pH changes significantly. The buffer capacity is highest when the concentrations of the weak acid and its conjugate base are equal.

Here are some additional resources that you may find helpful: