Using the model
Symbols, assumptions and limitations
νₐ and νᵦ are the positive whole-number stoichiometric coefficients of the acid and base in the balanced neutralization equation. The pH module converts their amounts to acid/base equivalents and is restricted to fully dissociated strong species at 25 °C, with additive volumes. Weak-acid, weak-base, activity, and dilution-heat effects require more detailed models.
Worked examples
See the method in practice
Unknown acid concentration
A 25.000 mL acid sample requiring 20.000 mL of 0.100 mol/L NaOH in a 1:1 reaction has concentration 0.080 mol/L.
Past equivalence
After equivalence in a strong acid–strong base titration, pH is set by the excess titrant moles divided by total solution volume.
Questions
Frequently asked
Is the equivalence point the same as the indicator endpoint?
The equivalence point is stoichiometric. The endpoint is an observed indicator change and should be selected to occur as close as possible to equivalence.
Why is pH 7 at equivalence here?
That result applies to a strong acid–strong base titration at 25 °C. Weak species produce acidic or basic conjugate ions at equivalence.
Can volume units be millilitres?
Yes. Both volumes may use millilitres because their common conversion factor cancels in the concentration relation; the pH calculation converts them internally to litres.
Sources & review
Equations and examples are checked against the references below. Results are educational and should be independently verified for safety-critical work.
OpenStax Chemistry — Acid–Base TitrationsWritten by the STEM Hub editorial team · Reviewed August 11, 2026 · Review methodology