Concept of pH and Buffers

Buffer solutions are aqueous solutions that resist changes in pH when small amounts of acid or base are added to them. 

• They prevent changes in pH by utilizing the equilibrium between a weak acid and its conjugate base (or a weak base and its conjugate acid) to neutralize added acid or base, maintaining the pH of the solution within a relatively narrow range.

Eg Blood maintain pH of 7.4 → contain carbonate/bicarbonate buffer –

Acidic Buffer Solutions:	Basic Buffer Solutions:
Composed of a weak acid and its conjugate base. These buffers are effective at maintaining a pH below 7. Examples Benzoic acid + sodium benzoate Acetic Acid/Sodium Acetate	Composed of a weak base and its conjugate acid. These buffers are effective at maintaining a pH above 7 Examples NH4OH and NH4Cl Ammonia/Ammonium Chloride Reaction with Acid (Hydrochloric Acid, HCl): NH3 + HCl →NH4Cl Reaction with Base (Sodium Hydroxide, NaOH): NH4Cl +NaOH →NH3 + NaCl + H2O