A 20.0-mL sample of a 0.125 M diprotic acid (H2A) solution is titrated with 0.1019 M KOH. The acid ionization constants for the acid are Ka1 = 5.2 * 10^-5 and Ka2 = 3.4 * 10^-10. At what added volume of base does each equivalence point occur?

Diprotic acids are acids that can donate two protons (H⁺ ions) per molecule in a solution. This characteristic leads to two distinct ionization steps, each with its own acid dissociation constant (Ka). Understanding the behavior of diprotic acids is crucial for determining the equivalence points during titration, as each proton donation corresponds to a different stage in the titration process.

Titration is a quantitative analytical method used to determine the concentration of a solute in a solution. The equivalence point in a titration occurs when the amount of titrant added is stoichiometrically equivalent to the amount of substance being titrated. For diprotic acids, there are two equivalence points, corresponding to the complete neutralization of each proton, which can be calculated using the initial concentration and volume of the acid solution.

An acid-base neutralization reaction involves the reaction of an acid with a base to produce water and a salt. In this context, KOH acts as a strong base that reacts with the diprotic acid H2A. The stoichiometry of the reaction is essential for calculating the volume of base required to reach each equivalence point, as it determines how many moles of KOH are needed to neutralize the protons released by the acid.