henderson hasselbalch equation calculator
Free calculate ph using henderson-hasselbalch equation for buffer solutions, weak acids, and weak bases.
Enter Buffer Data
pKa
Acid dissociation constant
M
Optional - for activity corrections
Results
Enter buffer data to calculate pH
Henderson-Hasselbalch Equation
Henderson-Hasselbalch Equation
pH = pKa + log([A⁻]/[HA])
- • pH = -log[H⁺]
- • pKa = -log(Ka)
- • [A⁻] = Conjugate base concentration
- • [HA] = Weak acid concentration
- • Valid when [A⁻]/[HA] ≈ 0.1 to 10
Buffer Properties
- • Maximum buffering at pH = pKa
- • Buffer capacity depends on concentrations
- • pH changes slowly with added acid/base
- • Used in biological systems
- • Range: pKa ± 1 pH unit