What is buffer? A buffer is a solution that can resist pH changes resulting from the addition of small amounts of acid or base. This property is essential for many processes and reactions that require specific and stable pH ranges.
Natural systems such as blood use buffers to maintain the body’s pH values within a narrow range necessary for good health. Buffers can also be used to maintain the proper pH of chemical solutions, growth media, and other aqueous environments.
It is a solution of a weak acid and its conjugate base
What is buffer?
A buffer is a solution of a weak acid and its conjugate base that can resist changes in pH. Buffer solutions have a pH of less than 7, and are usually made with an acidic acid and one of its salts, such as acetic acid and sodium acetate.
When a normal quantity of strong acid or base is added to a buffer, the pH hardly changes. This is because the acids and bases in a buffer do not significantly dissociate in water. Their equilibrium is governed by their acid and base dissociation constants, Ka (for acids) and Kb (for bases).
These constants are based on the concentration of ions in the solution, so they are more important for understanding what is happening than the pH.
For example, a drop of acetic acid in a buffer solution would cause acetic acid ions to dissociate in water, forming acetate ions and hydrogen ions. These ions do not change the pH because they are neutralized by the base. Likewise, when ammonia is added to a buffer solution, the ammonium ions dissociate in water to form ammonium hydroxide ions and hydrogen ions.
It is a solution of a weak base and its conjugate acid
Buffer is a water based solution of a weak base and its conjugate acid. It is used to keep the pH of a solution constant by resisting the change of pH caused by small additions of acids or bases.
If you add an acid to a buffer, the weak acid gives up one hydrogen ion to form water (H2O). This is called hydration. It is not a large reaction and does not cause much change to the pH of the solution.
This is because the strong base is not a strong acid and has a very low concentration in the solution. It does however react with the weak acid.
The hydration reaction can be seen in the following equation: HA + OH- - A-+ H2O. It is the hydration of the ion HA in water to form the conjugate acid and a new ion A-.
The strength of a weak acid is based on the equilibrium position for the dissociation of a single ion, called the acid ionisation constant or Ka (pKa). It can be calculated using the Henderson-Hasselbach equation. It is a very important equation and the student should understand how it works.
It is a solution of a strong acid and its conjugate base
A buffer is a solution of a strong acid and its conjugate base (*conjugate bases are the anions formed when an acid donates a proton) that resists changes in pH. Buffers are used in chemical reactions and other processes where the pH of a solution is changing quickly.
The capacity of a buffer is the amount of acid or base a solution can consume without significant changes in the pH. Generally, it is very helpful to start with similar starting concentrations of the acid and base to allow for the maximum capacity in buffering.
When a weak acid is added to water, it will dissociate into its conjugate base and the resulting anions. The conjugate base will then react with the H+ from the acid to form a weak acid: HA + OH- - A- - H2O, which is slightly different than the original solution.
This causes the original solution to maintain a nearly constant pH while the added acid or base neutralises it to make a new solution. This is called a buffer reaction equilibrium and is why a buffer is important for chemical reactions.
English
Français
Español
Português
Deutsch
Türkçe
Dutch
Italiano
Russian
Romaian