Neutralization Calculator

One mole of transferable protons or hydroxides. A mole of H₂SO₄ supplies two equivalents, so 0.1 M sulfuric acid delivers 0.2 equivalents per litre.

Where acid and base equivalents are equal. The required volume is the other solution's equivalents divided by this solution's normality — a single division once you are working in equivalents.

No, only for a strong acid with a strong base. A weak acid against a strong base leaves a basic conjugate and lands above 7; a weak base against a strong acid lands below.

Equivalence point is the stoichiometric truth; endpoint is where the indicator changes colour. A well-chosen indicator puts them close together, and the small gap between them is the titration error.

Because a weak partner buffers the excess, holding pH near its pKa instead of following the excess concentration directly. That calculation needs the Ka as well, so this page states the assumption rather than quietly breaking it.

Molarity multiplied by the number of equivalents per formula unit. 0.1 M H₂SO₄ is 0.2 N. It fell out of favour because the same solution has different normalities in different reactions, but it remains useful in titration work.

One whose colour change spans the pH at the equivalence point. Phenolphthalein, changing between 8.3 and 10.0, suits a weak acid against a strong base; methyl orange, changing between 3.1 and 4.4, suits a weak base against a strong acid.

A reagent pure and stable enough to be weighed directly into a standard solution — potassium hydrogen phthalate and sodium carbonate are the common ones. Sodium hydroxide is not: it absorbs water and carbon dioxide from air, so it must be standardised against a primary standard rather than weighed out.

Because near the equivalence point almost no unreacted acid or base is left to buffer the solution, so each drop changes the pH sharply. Away from it, the conjugate pair buffers and the curve is flat.

There is one equivalence point per proton, provided the pKa values are separated by at least about 4 units. Phosphoric acid shows two clear inflections and a third too weak to see, because its third pKa of 12.3 is too close to water's own ionisation.

Common causes are an air bubble in the burette tip that clears during the run, a wet burette that was not rinsed with the titrant, or overshooting past the true endpoint colour. All three add volume systematically rather than randomly.

Adding a known excess of one reagent, then titrating what is left over. It is used when the reaction is slow or the sample is insoluble — determining calcium carbonate in a shell, for instance, by dissolving it in excess acid and titrating the surplus.