Neutralization Calculator

A diprotic acid neutralises twice its molarity, which is exactly what normality is for.

Normality of the unknown0.4 eq/L

Unknown concentration0.2 mol/L

Titrant delivered1 × 10⁻² mol10 mmol

Analyte present5 × 10⁻³ mol

Equivalence ratio1 : 2protons exchanged per formula unit on each side

The proton counts differ, so molarity and normality part company here — the burette measures equivalents, and only the stoichiometry turns those back into moles.

The formula

C_analyte = C_titrant * V_titrant * n_titrant / (V_analyte * n_analyte)

Equivalents, not moles

What a titration actually measures is the number of protons exchanged. For a monoprotic acid against a monoprotic base that equals the number of moles and the distinction never surfaces. For sulfuric acid it does not: each formula unit supplies two protons, so a 0.1 M solution neutralises like a 0.2 M one and the stoichiometric factors above are what put the answer back onto a molar basis.

Endpoint and equivalence

These are not the same event. The equivalence point is where the reaction is stoichiometrically complete; the endpoint is where the indicator changes colour. A well chosen indicator puts them close enough together to ignore, and a badly chosen one introduces an error no arithmetic can remove.

Which denominator?

Most of the confusion in solution work is not arithmetic but bookkeeping. Molarity divides by the volume of the finished solution; molality divides by the mass of the solvent; percent by mass divides by the mass of the solution again. The three agree closely in dilute water and diverge sharply in concentrated acid, which is why a bottle labelled 98 % is also labelled 18.4 M without contradiction.