7.2.9—Sketch the pH titration curves of titrations

A titration curve plots pH against the volume of acid or alkali added. Its shape reflects the relative strengths of the reactants and the equivalence point where stoichiometric neutralisation is complete.

Strong/strong curves have a steep jump centred near pH 7; weak/strong combinations shift the equivalence pH because the conjugate ion hydrolyses. Half-equivalence can identify a weak acid’s pKa.

Adding NaOH to ethanoic acid gives a buffer region before the steep rise and an equivalence point above pH 7, unlike HCl/NaOH.

Equivalence point is not always pH 7 and is not the same as the point where an indicator happens to change colour.