Since a solvent also works as an acid or a base, the acidity and its range depend on
the solvent dissolving the acid. Full dissociation of an acid stronger than H3O+ gives H+
to water, forming H3O+ in an aqueous solution. For example, both HBr and HI dissociate
completely to become H3O+, and their acidities are similar. This kind of phenomenon is called the leveling effect, and all acidities become equal to that of H3O+. In measuring
the relative acidity of strong acids, it is necessary to use a solvent whose H+ affinity is
smaller than that of water, such as acetic acid or ethanol