pH Titration Calculator

Calculate pH at arbitrary points during titration, generate titration curves, estimate equivalence point and buffer-region pH. Supports strong/weak acid/base combinations, Henderson–Hasselbalch estimates and CSV export.

Compute pH at a single titration point

pH titrations: principles, calculations and practical guidance

Titration is a foundational analytical chemistry technique for determining concentration and acid/base strength. This calculator helps you estimate pH at arbitrary titrant additions, generate a titration curve table, and compute equivalence point volumes. It supports common lab scenarios: strong acid vs strong base, weak acid titrated with strong base (common in acid-base chemistry labs), and the reverse.

Key formulas

  • Equivalence volume (for monoprotic analyte): V_eq = (C_analyte × V_analyte) / C_titrant
  • Henderson–Hasselbalch: pH = pKa + log([A⁻]/[HA]) — good inside buffer region before equivalence.
  • Strong acid/base: before equivalence pH from excess H⁺ or OH⁻ via -log[H⁺] or 14+log[OH⁻].

Worked example

Example: 25.00 mL of 0.100 M acetic acid (pKa = 4.76) titrated with 0.100 M NaOH. Equivalence volume = (0.100×25.00)/0.100 = 25.00 mL. At 12.50 mL added (half-equivalence) the concentrations of HA and A⁻ are equal and pH ≈ pKa = 4.76.

Limitations and advice

This calculator uses idealized approximations. Ionic strength, temperature and activity corrections can shift observed pH. For precise buffer work include salts & ionic strength and use activity coefficients.

Frequently Asked Questions

1. Can I model polyprotic acids?
Not in this version — it supports monoprotic acids and bases only. Contact us if you need polyprotic support.
2. How is equivalence point determined?
Equivalence volume is calculated from stoichiometry: V_eq = (C_analyte×V_analyte)/C_titrant for monoprotic reactions.
3. When can I use Henderson–Hasselbalch?
Henderson–Hasselbalch applies in the buffer region where both HA and A⁻ are present in appreciable amounts (commonly 0.1–10× the acid's pKa).
4. Does it include ionic strength corrections?
Optional ionic strength input is provided but rigorous activity corrections are beyond scope and not performed automatically.
5. Can I export the titration curve?
Yes — after generating the curve click Download CSV to get a table of added volume vs pH.
6. Is temperature accounted for?
Temperature is used only to adjust water's pKw if provided; equilibrium constants are assumed at standard conditions unless specified.
7. How accurate are pH predictions?
Good for teaching and planning; for analytical-grade results include activity coefficients and precise equilibrium constants.
8. Can I simulate titration past equivalence?
Yes — the curve generator and single-point mode allow added volumes beyond equivalence to show asymptotic pH changes.
9. Do you handle dilution effects?
Yes — concentrations are recalculated based on total solution volume after titrant addition.
10. Can I change pKw or use non-aqueous solvents?
Not currently; the calculator assumes aqueous solution. For non-aqueous solvents results will be invalid.