Calculate pH at any point along a weak acid titration curve.
A weak acid titration curve has three regions: an initial pH set by the acid alone, a flat buffer region governed by the Henderson-Hasselbalch equation, and a steep rise past equivalence controlled by excess base. The flatness of the buffer region is precisely why buffers work, and its midpoint gives the pK_a directly.
Titration Curve
Buffer region: pH = pK_a + log([A⁻]/[HA]); past equivalence, pH follows excess hydroxide
Buffer region: pH = pK_a + log([A⁻]/[HA]); past equivalence, pH follows excess hydroxide A weak acid titration curve has three regions: an initial pH set by the acid alone, a flat buffer region governed by the Henderson-Hasselbalch equation, and a steep rise past equivalence controlled by excess base.
The flatness of the buffer region is precisely why buffers work, and its midpoint gives the pK_a directly.
This calculator takes 4 inputs: pKa of the acid, Initial moles of acid, Moles of base added, Total volume. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.