Calcolatore pH Tampone — Formula

Henderson-Hasselbalch Equation

Formula

pH = pKa + log₁₀([A⁻] / [HA])

Where:

  • pH = hydrogen ion activity
  • pKa = acid dissociation constant (log scale)
  • [A⁻] = concentration of conjugate base
  • [HA] = concentration of weak acid

    • When [A⁻] = [HA], pH = pKa. Buffers resist pH changes best within ±1 of the pKa.

    Esempio Risolto

    An acetate buffer with pKa = 4.76, [CH₃COO⁻] = 0.1 M, [CH₃COOH] = 0.1 M.

    1. pH = pKa + log₁₀([A⁻]/[HA])
    2. pH = 4.76 + log₁₀(0.1/0.1)
    3. pH = 4.76 + log₁₀(1)
    4. pH = 4.76 + 0
    5. pH = 4.76