What is a Buffer Solution?

A buffer solution is a solution that can maintain its pH value nearly constant even when small amounts of a strong acid or strong base are added.
The property by which a solution resists changes in pH is called buffer action.

Generally:

• Adding an acid decreases the pH.
• Adding a base increases the pH.

But a buffer solution resists these changes and keeps the pH stable.

Classification of Buffers :

(A) Acidic Buffers

An acidic buffer is a mixture of:

• a weak acid, and
• its salt formed with a strong base.

Their pH is usually less than 7.

Example:

• Acetic Acid (CH₃COOH)
• Sodium Acetate (CH₃COONa)

(B) Basic Buffers

A basic buffer is a mixture of:

• a weak base, and
• its salt formed with a strong acid.

Their pH is usually greater than 7.

Example:

• Ammonium Hydroxide (NH₄OH)
• Ammonium Chloride (NH₄Cl)

Buffer Capacity :

Buffer capacity is the measure of how effectively a buffer solution can resist changes in pH.

It is defined as the number of moles of strong acid or strong base required to change the pH of one liter of buffer solution by one unit.

It is usually represented by the symbol β (beta).

Importance of Buffer Solutions :

(A) In the Human Body

For the survival of living organisms, the pH of body fluids must remain stable. Human blood is a natural buffer solution containing carbonic acid and bicarbonate ions.

• Blood maintains its pH between 7.35 and 7.45.
• Even a small change in pH can be life-threatening.
• The buffer system prevents sudden pH changes even after consuming acidic foods.

(B) In Cells

• Cell fluids contain a phosphate buffer system.
• This helps biological reactions occur smoothly.

(C) In Agriculture

• Plant growth depends on soil pH.
• If soil becomes too acidic or too basic, plants cannot absorb nutrients properly.
• Carbonates and phosphates in soil act as buffers.
• They help maintain soil fertility by controlling soil pH.
• Fertilizers like ammonium sulfate may alter pH, but buffer action helps regulate the changes.

(D) In Industries

In many industries, product quality depends on maintaining proper pH.

Uses of Buffers:

• Syrups
• Injections
• Eye drops

Buffers help keep medicines stable during preparation and storage.

Other Applications:

• Textile dyeing
• Leather processing
• pH control in industrial processes

Buffers are widely used wherever pH stability is important.