Arrhenius acid

Arrhenius acid
Name	Arrhenius acid
Discovered	1884
Discoverer	Svante Arrhenius
Type	Acid definition

Arrhenius acid An Arrhenius acid is a substance that increases the concentration of hydrogen ions when dissolved in water. The concept underpins classical aqueous acid–base behavior and influenced later theories in physical chemistry, inorganic chemistry, and analytical chemistry.

Definition and basic concept

The Arrhenius definition states that an Arrhenius acid, when dissolved in water, produces an excess of hydrogen ions (H+), thereby lowering the pH of the solution. This operational statement links to experimental work in electrochemistry, thermodynamics, and kinetics as applied in laboratories at institutions such as the Royal Society and the Chemical Society. The practical formulation was used in curricula at universities like Uppsala University and University of Cambridge and informed industrial practices in firms such as DuPont and BASF.

Historical background and Svante Arrhenius

The term originates with Svante Arrhenius, whose 1884 publications proposed ionic dissociation to explain conductivity in electrolytes. Arrhenius's work intersected with contemporaries and institutions including Julius Thomsen, Walther Nernst, Arrhenius's contemporaries, and research cultures at the University of Stockholm and the Kaiser Wilhelm Society. His proposals preceded and influenced formulations by Jacobus Henricus van 't Hoff and debates with figures associated with the Royal Society of Chemistry and early 20th-century meetings such as those at the International Congress of Chemists.

Chemical properties and examples

Common Arrhenius acids include inorganic species like hydrochloric acid, sulfuric acid, and nitric acid, and organic examples such as acetic acid and citric acid when they dissociate in water. Strong Arrhenius acids such as sulfuric acid and hydrochloric acid fully dissociate to yield high concentrations of H+, while weak Arrhenius acids like acetic acid establish equilibria described by equilibrium constants used in studies by Guggenheim and Le Chatelier. Behavior in solution is characterized through measurements developed by researchers at institutions like Max Planck Society laboratories and published in journals affiliated with the American Chemical Society.

Comparison with Brønsted–Lowry and Lewis acids

Arrhenius acids are a subset of broader definitions: comparisons involve the Brønsted–Lowry acid–base theory and the Lewis acid–base theory. The Brønsted–Lowry framework, attributed to Johannes Nicolaus Brønsted and Thomas Martin Lowry, defines acids as proton donors, expanding applicability beyond aqueous systems and influencing work at centers such as Oxford University and Harvard University. The Lewis acid concept, associated with Gilbert N. Lewis, treats acids as electron-pair acceptors, relevant to coordination chemistry studied in contexts like the Royal Institution and industries such as BASF and Dow Chemical Company.

Limitations and scope of the theory

The Arrhenius definition is limited to aqueous media and cannot account for acid–base reactions in nonaqueous solvents explored at facilities like Argonne National Laboratory and Lawrence Berkeley National Laboratory. It fails to classify species acting as acids by proton transfer in gas-phase reactions relevant to research at CERN or as electron-pair acceptors central to organometallic chemistry studied at California Institute of Technology. Historical critiques emerged from figures working at University of Göttingen and during conferences involving the International Union of Pure and Applied Chemistry.

Applications in chemistry and industry

Arrhenius acids underpin processes in electroplating and corrosion control, and they are central to manufacturing at chemical firms like Dow Chemical Company, DuPont, and Solvay. They inform analytical protocols in titration methods developed by laboratories at National Institute of Standards and Technology, and industrial safety guidelines promulgated by organizations such as Occupational Safety and Health Administration and European Chemicals Agency. Agricultural applications include fertilizer production historically linked to discoveries by practitioners connected with Fritz Haber and the Haber–Bosch process.

Experimental demonstrations and measurement

Demonstrations of Arrhenius acidity use pH measurement, conductivity assays, and titrations with indicators like phenolphthalein standardized by bodies such as International Organization for Standardization and executed in labs at MIT and Stanford University. Electrochemical cells and potentiometric techniques, refined by scientists at Bell Labs and Lawrence Livermore National Laboratory, quantify hydrogen ion concentration, while spectroscopic methods from institutions like the Institute of Physical Chemistry of the Polish Academy of Sciences probe dissociation equilibria. Educational demonstrations appear in conferences and outreach programs sponsored by the Royal Society and science museums such as the Science Museum, London.

Category:Acid–base chemistry