Buffer capacity (acidic buffer) (β ≈ 2.303 × [HA][A-]/([HA]+[A-]))

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β ≈ 2.303 × [HA][A-]/([HA]+[A-])

What each symbol means

SymbolWhat it stands for
βBuffer capacity (mol L⁻¹ per pH unit) — resistance to pH change
[HA],[A^-]Equilibrium concentrations of acid and conjugate base

When to use this

Weak acid/conjugate base buffer; approximate for moderate concentrations; maximum near pH = pKa when [HA]=[A-].