Define Buffer Action?

Buffer action: the ability of the buffer solution to resist the changes in pH value on the addition of small amount of an acid or a base is known as buffer action.

For example: consider an acidic buffer such as a solution containing an equimolar amounts of acetic acid and sodium acetate, the solution contains a large number of sodium ions (Na+), acetate ions (CH3COO) and also a large number of undissociated acetic acid molecules.

CH3COONa (aq) ————-> CH3COO (aq) + Na+ (aq)
Suppose, a few drops of HCl are added to this buffer solution. This would provide hydrogen (H+) ions. These additional H+ ions would combine with the large reserve of CH3COO ions to form undissociated acetic acid molecules.
CH3COO (aq) + H+ (aq) ⇌ CH3COOH

The additional H+ ions are neutralized by CH3COO ions in the solution, hence there will be no change in its pH value. The reserve basicity of the solution is due to acetate ions.

Category: Ionic Equilibria

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