Electrochemical Contributions: Svante August Arrhenius (1859–1927)

Abstract

Svante August Arrhenius (Figure 1) was a Swedish scientist, educated as a physicist, but mostly contributed to chemistry. He established a new scientific filed of physical chemistry. Although he was not the only founder of this novel area combining physics and chemistry, his work was critically important for formulation and methodology of physical chemistry (Figure 2).

The most important scientific contribution made by Arrhenius was invention of the electrolytic dissociation theory. This theory explained ionic conductivity in salt/acid/base-solutions and provided background for research of electrochemical processes, including electroanalytical chemistry, electrolysis and battery chemistry. The first formulation of this theory, presently known as the Arrhenius dissociation theory, was made in his PhD thesis submitted in 1884: “Recherches sur la conductibilite galvanique des electrolytes” (Investigations on the galvanic conductivity of electrolytes). The theoretical assumption made by him was well supported with extensive experimental work made by Arrhenius, still being a student. The electrical conductivity in aqueous solutions of salts, acids and bases was explained by splitting the dissolved molecules or crystals in ions (positively charged cations and negatively charged anions). Particularly for acids and bases, he suggested their definitions based on generation of H⁺ and OH⁻ ions in the case of acids and bases, respectively. This definition of the acids and bases still keeps his name: Arrhenius acids and Arrhenius bases.

The Arrhenius theory had some connections to the early work made by Michael Faraday (English scientist, 1791–1867). Faraday, while studying electrolysis process, also proposed generation of cations and anions supporting conductivity in solutions. However, Faraday believed that their formation proceeds at electrode surfaces only upon pathing electric current through solutions. This explanation is incorrect according to the modern science. The Arrhenius theory proposed the cation and anion formation just upon dissolution of salts, acids, or bases, regardless the electric current applied. The dissociation of molecules into cations and anions (x2), according to the Arrhenius theory, proceeds due to weakening polaric chemical bonds in solutions based on solvents with the high dielectric constants (high polarity of the solvent molecules, water in the original Arrhenius work). This explanation appears to be correct.

It is interesting to note that the theory of the electrolytic dissociation was so much novel that it was poorly accepted by the scientific community, particularly, his PhD thesis received a low score. Notably, later his theory was awarded with the Nobel Prize. Arrhenius received the Nobel Prize for Chemistry in 1903, becoming the first Nobel laureate in Sweden. Shortly after that, in 1905, Arrhenius became the director of the Nobel Institute, where he remained in this important position until his death in 1927. In recognition of his scientific contributions, Arrhenius dissociation theory, Arrhenius equation, Arrhenius acid and Arrhenius base include his name.

The author declares no conflicts of interest.