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Chemistry · pH · titration

Acid-base titration curve and pH calculator

Compute pH during acid-base titrations (strong or weak acids and bases), and generate titration curves with step-by-step explanations.

All calculations run in your browser; no data leaves this calculator.

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How to use (3 steps)

  1. Select the titration type (strong/weak) and enter the concentrations and volumes.
  2. Choose a single-point pH or generate the full titration curve range.
  3. Tap Compute to view pH, regions (buffer/equivalence), and the calculation steps. Copy URL shares the exact setup. The results card below shows the curve and table.

A weak acid + strong base example is preloaded and calculated automatically so you can see results immediately.

Inputs

mol/L
mL
mol/L

Calculation mode

mL
mL

Results

How it's calculated

    How to read the titration result

    Start with the titration type, concentrations, and initial volume. Then decide whether you need one pH point or the full curve. Keep the first run as your baseline before you compare any other setup.

    What to check before computing

    Use the same concentration units for analyte and titrant, and make sure the weak-acid/weak-base constant matches the selected titration type. If the curve range is too short, you may miss the equivalence region.

    How to interpret the output

    Read the region label together with the pH and the step list. Before equivalence, buffer logic may dominate. Near equivalence, the conjugate species matters more. After equivalence, excess titrant usually controls the pH.

    Common mistakes to avoid

    See also

    FAQ

    What assumptions does this titration calculator make?

    It assumes monoprotic strong/weak acids and bases at 25 °C with ideal behaviour. Polyprotic species, activity coefficients, ionic strength, and temperature dependence are out of scope for this tool.

    Does the equivalence point always give pH 7?

    For strong acid and strong base, the equivalence point is near pH 7 at 25 °C. For weak acid with strong base, the conjugate base is present at equivalence, so the pH will be above 7.

    When is the Henderson-Hasselbalch equation valid?

    It is a good approximation before the equivalence point while both the acid/base and its conjugate are present. Near or after equivalence, this calculator switches to expressions for the dominant species.

    What should I do first on this page?

    Start with the minimum required inputs or the first action shown near the primary button. Keep optional settings at defaults for a baseline run, then change one setting at a time so you can explain what caused each output change.

    Why does this page differ from another tool?

    Different pages often use different defaults, units, rounding rules, or assumptions. Align those settings before comparing outputs. If differences remain, compare each intermediate step rather than only the final number.

    Practical interpretation checklist

    Before equivalence

    If both the weak species and its conjugate are present, the buffer region usually explains the pH trend. Use the step list to confirm when the page switches into that approximation.

    At equivalence

    Do not assume pH 7 automatically. Strong acid plus strong base is the simple case; weak systems can shift the equivalence pH above or below 7.

    After equivalence

    Check whether the result is now controlled by excess titrant. A sudden pH jump is expected if the final segment is dominated by strong acid or strong base left over after neutralization.

    When a result feels wrong

    Recheck units, constants, and the selected chemistry mode first. Then compare the exact added volume and equivalence volume instead of comparing only the final pH label.

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