Titration Calculator

Determine unknown concentration or predict equivalence volume for strong acid–strong base reactions. Real‑time curve simulation with adjustable analyte type. Calculations assume 25°C (pKw = 14.00)

Select analyte type. Titrant is automatically the opposite.
Volume must be in milliliters (mL).
For strong monoprotic acid or base. Stoichiometry 1:1 with titrant.
If analyte concentration is known, this field is used for consistency check.
All concentrations in mol/L, volumes in mL. Works for strong acid–strong base 1:1 reactions.
? Find unknown: HCl + NaOH (25.0 mL acid, 0.100 M base, 24.85 mL endpoint)
? Predict endpoint: 0.150 M HCl, 30.0 mL, 0.100 M NaOH
⚗️ Base as analyte: 20.0 mL NaOH, 0.120 M HCl, endpoint 18.5 mL
⟳ Reset to default
Privacy assured: All calculations and curve simulations run locally in your browser. No data is transmitted or stored.

Weak Acid – Strong Base Titration Module

For monoprotic weak acids (e.g., acetic acid) titrated with strong base. Determine unknown concentration or predict equivalence volume. Includes pH curve with buffer region.

Volume in milliliters (mL)
Typical: acetic acid Ka = 1.8×10-5 (pKa = 4.74)
? Unknown weak acid: 25.0 mL, 0.100 M NaOH, endpoint 18.5 mL, Ka=1.8e-5
? Predict Veq: 0.150 M weak acid, 30.0 mL, 0.100 M NaOH
⟳ Reset weak acid fields

Titration Principles & Analytical Relevance

Acid-base titration is a fundamental volumetric analysis technique used to determine the concentration of an unknown acid or base. In strong acid–strong base titrations, the reaction goes to completion: H+ + OH- → H2O. The equivalence point occurs at pH 7.00 (25°C) and the titration curve shows a sharp vertical jump. This calculator solves for the unknown concentration using the relationship Canalyte·Vanalyte = Ctitrant·Veq for 1:1 stoichiometry. Use the dropdown to specify whether the analyte is an acid or a base — the pH curve will adapt accordingly.

At equivalence: nanalyte = ntitrant → Canalyte · Vanalyte = Ctitrant · Veq

pH before equivalence: from remaining H+ or OH-; after equivalence: from excess titrant.

How to Use the Calculator (Two Modes)

  • Mode 1 – Determine unknown concentration: Leave Analyte Concentration empty. Enter analyte volume, titrant concentration, and the volume of titrant used to reach endpoint. The calculator will compute the unknown concentration and plot the full pH curve.
  • Mode 2 – Predict equivalence volume: Enter analyte concentration (along with its volume) and titrant concentration. The calculator will compute the theoretical endpoint volume and compare it with any manually entered endpoint volume (useful for validation or pre‑lab planning).
  • Analyte type: Select whether the flask contains a strong acid or a strong base. The titrant is always the opposite. The pH curve will automatically adjust.

Mathematical Derivation & Simulation

For a strong monoprotic acid (HA) titrated with strong base (NaOH): before equivalence [H+] = (CaVa – CbVb)/(Va+Vb), after equivalence [OH-] = (CbVb – CaVa)/(Va+Vb). For a strong base titrated with strong acid, the formulas are symmetric: before equivalence [OH-] = (CbVb – CaVa)/(Va+Vb) and after equivalence [H+] = (CaVa – CbVb)/(Va+Vb). The tool automatically selects the correct regime based on the analyte type.

Real‑World Applications & Case Study

Industrial Quality Control: HCl in Pickling Bath

A technician takes 10.00 mL of hydrochloric acid solution, titrates with 0.1000 M NaOH, and records an endpoint volume of 24.85 mL. By leaving the analyte concentration empty, the calculator returns Ca = 0.2485 M. In a second scenario, the lab manager wants to prepare a titration where 25.0 mL of 0.150 M HCl is titrated with 0.100 M NaOH. By entering the known concentration, the tool predicts Veq = 37.50 mL, allowing the analyst to set up the burette accordingly. If the analyte is a base, simply select "Strong base" and the same principles apply.

Common Pitfalls & Expert Tips

  • Indicator choice: For strong acid–strong base, phenolphthalein (pH 8.2–10) or methyl orange (3.1–4.4) works, but phenolphthalein is preferred due to sharp color change near equivalence.
  • CO2 interference: In strong base titrations, atmospheric CO2 can form carbonic acid; always use freshly boiled distilled water.
  • Volume consistency: Ensure burette readings are recorded to 0.01 mL precision for high accuracy.
  • Stoichiometry check: For diprotic acids (H2SO4), the mole ratio becomes 2:1 (base:acid). This calculator assumes 1:1 – use only for monoprotic strong acids/bases.

Analytical Chemistry Foundation – This tool implements established principles from Skoog, West, Holler & Crouch's “Fundamentals of Analytical Chemistry” and follows IUPAC guidelines for volumetric calculations. The titration curve simulation uses rigorous strong acid‑strong base equations.The tool is maintained by the GetZenQuery Tech team and is based solely on peer‑reviewed chemical literature.Last reviewed March 2026.

Frequently Asked Questions

The calculator will compute the theoretical endpoint volume from the provided concentration and compare it with your entered volume. This allows you to verify consistency (e.g., to check if your experimental endpoint matches the theoretical prediction).

This calculator is optimized for strong monoprotic acid–strong base systems. Weak acid titrations involve buffer regions and different equivalence pH (>7). For weak acid calculations, a dedicated weak‑acid titration tool is recommended.

The curve is simulated by solving for pH at 200 discrete points between 0 and 1.8×V_eq using the strong acid/base pH equations described above. The result is a smooth sigmoidal curve with a sharp jump at equivalence. The curve direction depends on the analyte type (acid or base).

The simulation assumes 25°C, where pKw = 14.00. For other temperatures, slight variations occur, but the general curve shape remains valid for educational purposes.
References: LibreTexts Analytical Chemistry; Skoog, D.A. et al. “Fundamentals of Analytical Chemistry” (9th ed); IUPAC Guidelines.