What is a buffer solution?

A buffer solution resists changes in pH when small amounts of acid or base are added.

• Made of a weak acid + its conjugate base (acidic buffer) or weak base + its conjugate acid (basic buffer).

Example: Acetic acid + Sodium acetate → acidic buffer (pH ~4.75)

How it works:

• Add acid → conjugate base neutralises it
• Add base → weak acid neutralises it

Biological importance: Blood pH maintained at 7.35–7.45 by carbonic acid, bicarbonate buffer.

A buffer solution resists pH changes by neutralising added acids or bases, essential in biological systems and laboratory chemistry.