What is the titration equivalence formula?

At the equivalence point, n_a × M_a × V_a = n_b × M_b × V_b, where n_a and n_b are the acid/base stoichiometric coefficients in the balanced reaction.

What is the difference between equivalence and end point?

Equivalence is when stoichiometrically equivalent amounts have reacted. End point is the colour change of the indicator, which is chosen to be as close as possible to the equivalence point.

How do I choose the right indicator?

Pick an indicator whose colour-change pH matches the pH at the equivalence point. Strong acid + strong base: any indicator works. Weak acid + strong base: pick one that changes above pH 7 (phenolphthalein). Strong acid + weak base: pick one that changes below pH 7 (methyl orange).

What if the acid is diprotic (e.g. H₂SO₄)?

Set n_a = 2 (2 mol acid releases 2 mol H⁺) and balance against the base. The calculator handles any whole-number stoichiometry.

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NSW · HSCChemistry

Titration calculator

Solve for unknown concentration or volume using n_a M_a V_a = n_b M_b V_b at the equivalence point.

Inputs

Stoichiometry: n_a moles of acid react with n_b moles of base.

n_a (acid coef)n_b (base coef)

Solve forM_acid (mol/L)V_acid (mL)M_base (mol/L)V_base (mL)

Result

M_acid

0.1000mol/L

At the equivalence point: n_a × M_a × V_a = n_b × M_b × V_b. Volumes cancel if they use the same unit.

How this calculator works

It rearranges the equivalence-point relation n_a M_a V_a = n_b M_b V_b for whichever variable is unknown. The coefficients n_a and n_b come from the balanced equation: HCl + NaOH → NaCl + H₂O has n_a = n_b = 1; H₂SO₄ + 2 NaOH → Na₂SO₄ + 2 H₂O has n_a = 1, n_b = 2.

Common questions

What is the titration equivalence formula?: At the equivalence point, n_a × M_a × V_a = n_b × M_b × V_b, where n_a and n_b are the acid/base stoichiometric coefficients in the balanced reaction.
What is the difference between equivalence and end point?: Equivalence is when stoichiometrically equivalent amounts have reacted. End point is the colour change of the indicator, which is chosen to be as close as possible to the equivalence point.
How do I choose the right indicator?: Pick an indicator whose colour-change pH matches the pH at the equivalence point. Strong acid + strong base: any indicator works. Weak acid + strong base: pick one that changes above pH 7 (phenolphthalein). Strong acid + weak base: pick one that changes below pH 7 (methyl orange).
What if the acid is diprotic (e.g. H₂SO₄)?: Set n_a = 2 (2 mol acid releases 2 mol H⁺) and balance against the base. The calculator handles any whole-number stoichiometry.