A buffer is a solution that can maintain its pH after the addition of acidic or basic components. It can neutralize modest amounts of additional acid or base, keeping the pH of the solution reasonably constant. This is critical for procedures and/or reactions that require precise and consistent pH levels. Buffer solutions have a functional pH range and capacity that determine how much acid/base can be neutralized before the pH changes, as well as how much it changes.
Buffer Solution Types: Acidic and alkaline buffers are the two main types of buffer solutions that can be genetically classified.
Acidic buffer:
These solutions are used to keep acidic surroundings acidic, as the name implies. Acid buffer is made by combining a weak acid and its salt with a strong base to create an acidic pH. The pH of an aqueous solution containing an equal amount of acetic acid and sodium acetate is 4.74.These solutions have a pH of less than seven and are made up of a weak acid and its salt.A mixture of sodium acetate and acetic acid (pH = 4.75) is an acidic buffer solution.
Alkaline buffer
These buffer solutions are used in order to maintain simplicity. A basic buffer, with a basic pH, is created by combining a strong acid with a weak base and its salt. Aqueous solutions with equal parts of ammonium hydroxide and ammonium chloride have a pH of 9.25.These solutions contain a weak base and a weak base salt, and their pH is larger than seven. An alkaline buffer solution is a combination of ammonium hydroxide and ammonium chloride (pH = 9.25).
To properly maintain a pH range, a buffer must have a weak conjugate acid-base pair, which can be either a weak acid and its conjugate base, or a weak base and its conjugate acid. When making the buffer, the choice between the two will simply be determined by the pH desired.
For example, the following could function as buffers when together in solution:
HAC + NaAC → Na+ + H+ + 2AC−
Where, HAC=Acetic acid; NaAC = Sodium acetate.
If alkali (NaOH) is added to this system, it will form salt and no free H+ or OH− will be available.
HAC + NaAC + NaOH → 2NaAC + H2O
If acid (HCl) is added to this system, it will also form salt and no free H+ or OH− will be available.
HAC + NaAC + HCl NaCl + 2HAC
In either case, the concentration of hydrogen ions remains unchanged. The buffer absorbs hydrogen or hydroxyl ions.
The pH of buffers can be determined using the Henderson-Hasselbalch equation.
Uses of Buffer Solutions
- Buffer solutions are referred to by various names, including pH buffers and hydrogen ion buffers.
- Buffers, such as bicarbonate and carbonic acid, are used to adjust pH levels in animal blood. In addition, buffer solutions are employed to maintain an optimal pH for enzyme activity in many organisms.
- In the absence of certain buffers, enzyme action may be slowed, enzyme characteristics lost, or enzymes denaturated. This denaturation process can irreversibly impair the enzymes' catalytic function.