Buffer Solution Calculator
Acidic Buffer pH
Henderson-Hasselbalch for weak acid + conjugate base
Basic Buffer pH
Henderson-Hasselbalch for weak base + conjugate acid
Ratio for Target pH
Find the [A⁻]/[HA] ratio needed for a desired pH
Formula
pH = pKa + log([A⁻]/[HA]) | pOH = pKb + log([BH⁺]/[B]) | Buffer range: pKa ± 1
Frequently Asked Questions
What is the Henderson-Hasselbalch equation?
pH = pKa + log([A⁻]/[HA]). It calculates the pH of a buffer solution from the pKa of the weak acid and the ratio of conjugate base to acid concentrations. For basic buffers: pOH = pKb + log([BH⁺]/[B]).
What makes a good buffer?
A good buffer has: (1) pKa close to the desired pH (within ±1), (2) high concentrations of both acid and conjugate base, (3) equal or near-equal concentrations of acid and base for maximum capacity. Buffer capacity is highest when [A⁻] = [HA].
What is buffer capacity?
Buffer capacity is the amount of strong acid or base a buffer can absorb before significant pH change. It is maximized when pH = pKa and increases with total buffer concentration.
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