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Buffer Capacity

Buffer capacity measures a buffer solution's ability to resist changes in pH when acids or bases are added.

Key Concepts​

  • Definition: Amount of acid or base a buffer can neutralize before a significant pH change occurs
  • Factors Affecting Buffer Capacity:
    • Concentration of buffer components: Higher concentrations → higher capacity
    • Ratio of conjugate acid to base: Optimal when [HA] ≈ [A⁻] (pH ≈ pKa)

Henderson-Hasselbalch Equation​

  • pH = pKa + log([A⁻]/[HA])
  • Shows how pH changes with added acid or base

Practical Example​

  • A buffer made from acetic acid (CH₃COOH) and sodium acetate (CH₃COONa)
    • Adding H⁺ → reacts with CH₃COO⁻
    • Adding OH⁻ → reacts with CH₃COOH
    • pH remains relatively stable

Importance​

  • Biological systems: Blood and intracellular fluid
  • Industrial applications: Pharmaceuticals, chemical manufacturing
  • Helps understand limits of buffer effectiveness

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