levelling effect

https://doi.org/10.1351/goldbook.L03506
The tendency of a solvent to make all @[email protected] whose @[email protected] exceeds a certain value appear equally acidic. It is due to the complete transfer to a @[email protected] solvent of a @[email protected] from a dissolved acid stronger than the @[email protected] of the solvent. The only acid present to any significant extent in all such solutions is the @[email protected] For example, the solvent water has a levelling effect on the acidities of HClO4, HCl and HI: aqueous solutions of these acids at the same (moderately low) concentrations have the same acidities. A corresponding levelling effect applies to strong bases @[email protected] solvents.
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1135 [Terms] [Paper]