Free Buffer pH Calculator
Calculate the pH of a buffer solution using the Henderson-Hasselbalch equation from pKa and the ratio of conjugate base to acid concentrations.
M
M
Buffer pH
4.76
Base/Acid Ratio1.0000
Buffer pH vs pKa of Weak Acid
Henderson-Hasselbalch Equation
Formula
pH = pKa + log₁₀([A⁻] / [HA])
Where:
When [A⁻] = [HA], pH = pKa. Buffers resist pH changes best within ±1 of the pKa.
Example Calculation
An acetate buffer with pKa = 4.76, [CH₃COO⁻] = 0.1 M, [CH₃COOH] = 0.1 M.
- 01pH = pKa + log₁₀([A⁻]/[HA])
- 02pH = 4.76 + log₁₀(0.1/0.1)
- 03pH = 4.76 + log₁₀(1)
- 04pH = 4.76 + 0
- 05pH = 4.76
Frequently Asked Questions
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