Acid Base Titration Calculator

Example titration data

Use this example to verify the calculator output before entering your own measurements.

Enter these values into the form above to reproduce the example calculation.

Formulas used in the titration calculator

The calculator first determines the initial moles of analyte and titrant from concentration multiplied by volume. It then identifies whether the system is before equivalence, exactly at equivalence, or after equivalence, based on the limiting reagent for the neutralization reaction.

For strong acid–strong base systems, the pH is obtained from the concentration of excess hydrogen or hydroxide ions, using pH = −log₁₀[H⁺] and pOH = −log₁₀[OH⁻], with pH + pOH ≈ 14 at twenty five degrees Celsius.

When a weak acid is titrated by a strong base, the tool applies the Henderson–Hasselbalch relationship in the buffer region, pH = pKa + log([A⁻]/[HA]). At equivalence, it treats the conjugate base as a weak base and computes hydrolysis using Kb = Kw/Ka and the resulting hydroxide concentration.

The same reasoning applies symmetrically for weak bases titrated by strong acids, using pOH = pKb + log([B]/[BH⁺]) in buffer regions and converting back to pH with pH = 14 − pOH for final reporting.

How to use this calculator

1. Select the titration type that matches your experiment, distinguishing whether the analyte or titrant is weak or strong.
2. Enter the analyte concentration and volume, making sure your units are in mol per liter and milliliters respectively.
3. Enter the titrant concentration and the volume added at the point where you wish to evaluate the pH.
4. If the analyte or titrant is weak, provide an appropriate pKa or pKb value taken from reference tables or literature data.
5. Press the calculate button to obtain the titration summary, including the equivalence volume of titrant and pH at the chosen volume.
6. Compare the reported region relative to equivalence with your indicator color change or measured pH to interpret experimental behavior.
7. Use the CSV or PDF download options to archive your results or include them within electronic laboratory notebooks and reports.

In-depth notes on acid base titration

Understanding acid base titration

Acid base titration is a volumetric analytical technique used to determine an unknown concentration by reacting an acid with a base of known concentration. This calculator automates the stoichiometric steps and equilibrium corrections, letting you focus on interpreting pH changes and equivalence points instead of repeated arithmetic. It is widely used in environmental, pharmaceutical, and food analysis.

Key inputs handled by the calculator

You provide the initial concentration and volume of the analyte, the concentration of the titrant, and the volume added at the point of interest. For weak systems, you can also supply a pKa or pKb value, allowing the calculator to switch between buffer equations and hydrolysis expressions where appropriate.

Strong versus weak titration scenarios

For strong acid with strong base titrations, the pH is determined primarily by the limiting reagent and the position relative to the equivalence point. When a weak acid is titrated with a strong base, this tool applies buffer relationships before equivalence and conjugate base hydrolysis exactly at equivalence, giving insight into the underlying equilibrium chemistry. The same logic works symmetrically when titrating a strong base.

Working with polyprotic and biochemical systems

Many real solutions contain polyprotic species or amino acids with multiple ionizable groups. After estimating titration behavior, you can refine pH predictions using the linked Polyprotic Acid pH Calculator. For protein or peptide work, the Amino Acid Charge vs pH Calculator helps connect titration curves with net molecular charge. Together, these tools support deeper study of complex titration profiles.

Using equilibrium constants and pK values

Weak acids and bases require equilibrium treatment beyond simple mole balances. By entering a pKa or pKb, you allow the calculator to estimate buffer pH via the Henderson–Hasselbalch equation and to compute hydrolysis at equivalence using Ka or Kb derived from the water ion product. This avoids solving quadratic equations by hand for each new mixture.

Laboratory applications and teaching benefits

Students can quickly explore how changing concentration, volume, or acid strength shifts the titration curve and equivalence volume. In teaching laboratories, instructors may use the tool to prepare pre-lab predictions, verify student results, or illustrate titration regions directly on projected screens without manual graphing.

Limitations and good practice

The model assumes monoprotic acids or bases for direct titration calculations, ideal solution behavior, and measurements near twenty five degrees Celsius. Extremely dilute solutions, very concentrated reagents, or non aqueous solvents may deviate from these assumptions, so experimental calibration and sound laboratory technique remain essential. Always compare numerical predictions with indicator color changes or electrode readings.

Frequently asked questions

What assumptions does the titration model use?

The calculator assumes aqueous solutions at approximately twenty five degrees Celsius, complete dissociation for strong acids and bases, and monoprotic behavior for equilibrium steps. Activity coefficients are not included, so very concentrated or highly ionic solutions may require experimental calibration.

Can I use this tool for polyprotic acids?

Direct calculations treat a single acidic or basic site, suitable for many laboratory exercises. For polyprotic systems, use the titration output as a first estimate, then refine equilibrium pH with the dedicated polyprotic acid pH calculator linked on this page.

How accurate are pH values near the equivalence point?

For strong acid–strong base titrations, predicted pH values near equivalence are typically very reliable. For weak systems, buffer capacity changes rapidly, so glass electrode measurements or indicator ranges should be checked alongside the numerical estimates.

Do I need to enter pKa or pKb for every titration?

You only need a pKa or pKb when the analyte or titrant is weak. Strong acid with strong base titrations can be computed using stoichiometry alone, so the calculator will ignore an optional pK value if it is not required.

Why does the calculator sometimes report extremely high or low pH?

Very small or very large hydrogen or hydroxide concentrations can occur when reagent volumes are extreme. The calculator caps pH values within a conventional zero to fourteen window, which is adequate for most educational and general laboratory purposes.

Can I export my results for later analysis?

Yes. After performing a calculation, use the CSV download button to obtain a spreadsheet friendly file, or the PDF option to save a compact report containing your current inputs and summary of titration results.