An HCl solution of unknown concentration is titrated with standardized NaOH. What quantity is calculated from the NaOH volume delivered at the equivalence point?

Core Concept

Standardized NaOH carries a known molarity, so multiplying it by the delivered volume gives moles of OH⁻ added. At the equivalence point those moles match the moles of H⁺ originally present, because the acid-base ratio is 1:1. Dividing by the acid sample's volume then yields the unknown HCl concentration, which is precisely what a titration is designed to find.