Parts of a Titration Curve – Label the Points and Regions

All 8 boxes on the diagram

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The axes 2

pH The vertical axis: how acidic or basic the mixture is.
Volume of titrant added The horizontal axis: how much base has been run in.

The curve 6

Equivalence point Acid and base have been mixed in exactly matching amounts.
Initial pH The pH of the acid before any base is added.
Buffer region Here the pH changes little as base is added.
Half-equivalence point Half the acid is neutralized. Here the pH equals pKa.
Steep rise Close to equivalence, a little base changes the pH a lot.
Excess titrant Past equivalence, the extra base sets the pH.

How this list was compiled: Every name checked on 2026-09-30 and kept only where at least two of these use it. (1) Wikipedia, Titration curve, Acid-base titration and Titration, https://en.wikipedia.org/wiki/Titration_curve and https://en.wikipedia.org/wiki/Acid%E2%80%93base_titration : pH against the volume of titrant; the initial pH; buffer regions; the half-equivalence point, where pH equals pKa for a weak acid; the equivalence point, above pH 7 for a weak acid and a strong base; the pH after the equivalence point; how the end point differs from the equivalence point. (2) Jim Clark, Chemguide, pH (titration) curves, https://www.chemguide.co.uk/physical/acidbaseeqia/phcurves.html : the equivalence point; the pH changing little, then surging very steeply near it; the buffer solution set up on the way; the curve once the alkali is in excess. (3) For the words buffer region and half-equivalence point together, search-result passages of two exam-preparation books on archive.org, https://archive.org/details/crackingapchemis0000unse and https://archive.org/details/mcatgeneralchemi0000unse_a0f2 . Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry. The curve is computed from the charge balance; nothing is traced or copied. Licence: own work

How it works

The parts of a titration curve are its two axes and the points and regions along the line. This chart shows a weak acid titrated with a strong base, the case that has every part.

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Reading the chart

The curve plots pH against the volume of titrant added. It starts at the initial pH of the acid and climbs gently through the buffer region, where added base changes the pH little.

The two key points

At the half-equivalence point half the acid is neutralized and the pH equals its pKa. At the equivalence point the base added exactly matches the acid. Around it the curve rises steeply; after it, excess titrant sets the pH.

Questions and answers

What are the parts of a titration curve?

The pH axis and the volume axis, then along the line: the initial pH, the buffer region, the half-equivalence point, the steep rise with the equivalence point on it, and the level part where the titrant is in excess.

What is the difference between the equivalence point and the end point?

The equivalence point is where acid and base have been mixed in exactly matching amounts. At the end point the indicator changes color. A well-chosen indicator puts the two very close together.

Why is the half-equivalence point important?

Half the weak acid has been turned into its conjugate base, so the two are present in equal amounts and the pH equals the acid's pKa. Reading the pH there gives the pKa.

Is the equivalence point always at pH 7?

No. For a weak acid titrated with a strong base, as on this chart, the pH at the equivalence point is greater than 7. It depends on how strong the acid and the base are.