A 20.0-mL sample of 0.115 M sulfurous acid (H₂SO₃) solution is titrated with 0.1014 M KOH. At what added volume of base solution does each equivalence point occur?

Key Concepts

Titration

Titration is a quantitative analytical technique used to determine the concentration of a solute in a solution. It involves the gradual addition of a titrant (in this case, KOH) to a solution of the analyte (H2SO3) until the reaction reaches its equivalence point, where stoichiometrically equivalent amounts of acid and base have reacted.

Equivalence Point

The equivalence point in a titration is the stage at which the amount of titrant added is exactly enough to completely neutralize the analyte solution. For a diprotic acid like sulfurous acid, there are two equivalence points corresponding to the neutralization of each acidic proton, which must be calculated based on the stoichiometry of the reaction.

Molarity and Volume Relationship

Molarity (M) is defined as the number of moles of solute per liter of solution. In titration calculations, the relationship between the molarity and volume of the acid and base solutions is crucial. The formula M1V1 = M2V2 allows us to determine the volume of titrant needed to reach the equivalence point, where M1 and V1 are the molarity and volume of the acid, and M2 and V2 are those of the base.