Titration Curve Simulator

Choose the analyte type, its initial volume and concentration, and the titrant concentration. Calculate, then move the volume slider or enter an exact added volume. CSV contains the calculated curve, equivalence, half-equivalence and current point. Changing chemical inputs clears the result until you calculate again.

Presets and custom values. Acetic/formic acid and ammonia/methylamine presets supply representative pKa/pKb values. Advanced settings allow a custom value and a larger plot range; zero selects 2.2 times the equivalence volume. The plot always includes equivalence. Concentrations may be entered in scientific notation.

Model. The entire curve solves mass balance, charge balance and water dissociation at 25 °C (Kw = 10⁻¹⁴). Strong acid/base species dissociate fully; weak species are monoprotic. Dilution and conjugate-species hydrolysis are included. This removes artificial jumps from piecewise buffer approximations. At half-equivalence, pH ≈ pKa (or pOH ≈ pKb) only when water and free acid/base contributions are negligible. The model is ideal: activities, temperature changes, CO₂ uptake, mixed/polyprotic acids and indicator consumption are excluded. The former phosphoric-acid approximation is not offered.

Indicators. Purple lines bound the indicator pH transition range. The reported volume interval is computed from those two pH limits, even beyond the plotted range. Its error is 100 × (volume / equivalence volume − 1). A small interval near zero is useful; merely containing the equivalence pH does not establish suitability. These are theoretical bounds, not a prediction of the exact visible colour change.