Arrhenius’s theory of electrolytic

Between 1865 and 1887, Dmitri 1. Mendeleev developed the chemical theory of solutions. According to this theory, the dissolution process is the chemical interaction between the solutes and the solvent. Upon dissolution of salts, dissolved hydrates are formed in the aqueous solution which are analogous to the solid crystal hydrates. In 1889, Mendeleev criticized Arrhenius s theory of electrolytic dissociation. Arrhenius, in turn, did not accept the idea that hydrates exist in solutions. 

Ostwald resigned the professorship at Leipzig in 1905, after differences with the university authorities. During his period there he trained a large number of students, and directed the research of a number of workers, including British and American, who spread the new physical chemistry to all countries. The school was mainly based on Arrhenius s theory of electrolytic dissociation, van t Hoff s osmotic theory of solutions, and the applications to chemistry of the laws of thermodynamics. In 1909 Ostwald received the Nobel Prize for his work on catalysis. ... 

G. Fitzgerald, in a rambling and irrelevant memorial lecture on Helmholtz, went out of his way to attack both van t HoflF s theory of dilute solutions and Arrhenius s theory of electrolytic dissociation. The sustained opposition of... 

This ultimately led to Svante Arrhenius s theory of electrolytic dissociation and the evolution of a new division in the chemical field, known today as physical chemistry... 

On Thalen, see Widmalm, Det oppna laboratoriet (note 54), 77-130, especially 106-113. Thalen s atheoretical commitment became clear during his negative (although understandable) reaction toward Arrhenius s theory of electrolytical dissociation. 

He employed a range of adds and he correlated the affinity (reactivity) of an acid with its catalytic power. He was therefore in a good position to appreciate Arrhenius s concept of electrolytic dissociation when the latter sent him a copy of his doctoral thesis in 1884. In 1887 Ostwald moved to Leipzig as professor of physical chemistry. For the remainder of his career he championed the ionic theory of Arrhenius against much opposition. He provided additional evidence for the theory, and he developed the theory of add-base indicators. He resigned from Leipzig in 1905, and in his retirement he worked on the theory of colours, as well as espousing many humanistic, educational and cultural causes. 

Amplitude of a process, 114. Andrew s diagram, 173 Anisotropic bodies, 193 Aphorism of Clausius, 83, 92 Arrhenius theory of electrolytic dissociation, 301 Aschistic process, 31, 36, 51 Atmosphere, 39 Atomic energy, 26 Availability, 65, 66 Available energy, 66, 77, 80, 98, 101... 

The theory of electrolytic dissociation was not immediately recognized universally, despite the fact that it could qualitatively and quantitatively explain certain fundamental properties of electrolyte solutions. For many scientists the reasons for spontaneous dissociation of stable compounds were obscure. Thus, an energy of about 770kJ/mol is required to break up the bonds in the lattice of NaCl, and about 430kJ/mol is required to split H l bonds during the formation of hydrochloric acid solution. Yet the energy of thermal motions in these compounds is not above lOkJ/mol. It was the weak point of Arrhenius s theory that this mismatch could not be explained. 

Some experiments with cane sugar seemed to support this, but since the results with alcohol were normal, he repeated the experiments with sugar and found that at extreme dilution the extrapolated value is still 18 7. He now accepted the theory of electrolytic dissociation the molecular depressions of salts have limiting values conforming to the previsions of Arrhenius . Some accurate measurements were made in Ostwald s laboratory by H. C. Jones. ... 

Van t Hoff s main contribution to physical chemistry was probably his theory of dilute solutions, first published in 1886 (see p. 654) and in the first volume of the Zeitschrift fur physikalische Chemie, which also contained Arrhenius s paper on electrolytic dissociation. Van t Hoff later published an important paper on solid solutions. ... 

A treatment on the basis of complete ionisation and electrical interionic action given by S. R. Milner was much simplified by P. Debye and E. Hiickel. G. N. Lewis proposed an arbitrary function of the concentration called the fugacity /, and an activity <2, such that the laws of ideal solutions are obeyed if activities are substituted for concentrations,/c = a/c being called the activity coefficient. The theory of Debye and Hiickel shows that the activity coefficient is a function of the square root of the concentration of the completely ionised electrolyte multiplied by a factor w depending on the valencies of the ions (an effect which has no place in Arrhenius s theory) /c = i - Awc >, where is a function of temperature and the properties of the pure solvent. In place of Arrhenius s a, the degree of dissociation, a conductivity coefficient / =A/Ao (or A/Aoo), which is numerically different from/c is found from the equation where a is a constant depending on the temperature... 

Over 100 years have passed since Arrhenius published his Dissociation Theory of Electrolytes in 1887. Prior to this it was believed that electrolytes did not dissociate into ions in water until current was passed, and Arrhenius work was not well received. It was some decades after this that Born s theory of ionic solvation, and then, Debye and Huckel s theory of ionic activities in... 

Arrhenius received the 1903 Nobel Prize in chemistry for his work on electrolytes. He found that a solution conducts electricity because the solute dissociates immediately upon dissolving into electrically charged particles (ions). The movement of these ions toward oppositely charged electrodes causes the solution to be a conductor. According to Arrhenius s theory, solutions that are relatively poor conductors contain electrolytes that are only partly dissociated. Arrhenius also believed that ions exist in solution whether or not an electric current is present. In other words, the electric current does not cause the formation of ions. Remember that positive ions are cations negative ions are anions. 

A century ago, van t Hoff s (1 ) pioneering work on the gas-solution analogy was followed by Arrhenius (2 ) theory of partial dissociation of electrolytes in solutions. Later, electrolytes came to be classified as weak or strong with the supposition that the former are partially dissociated whereas the latter are completely dissociated in the given solvent However, with... 

One of the difficulties in understanding the true mechanism of the process of electrolysis at the time that Faraday enunciated his laws of electrolysis was the absence of the idea of spontaneous electrolytic dissociation, postulated much later by Clausius and by Arrhenius. In fact, Faraday believed that the electric force at (between) electrodes split up molecules in the electrolyte, giving rise to conductivity. This idea was connected with Freiherr von Grotthus s theory of a series of dissociations and recombinations of charged species in the conductance of aqueous solutions. 

Spectroscope developed Bunsen and Kirchhoff 1869 Mendeleev s first periodic table organizes 63 known elements 1885 Balmer formula for visible H spectrum 1894 First "inert gas" discovered 1895 X rays discovered Roentgen 1896 Radioactivity discovered Becquerel 1874 Tetrahedral carbon atom Le Bel and van t Hoff 1884 Dissociation theory of electrolytes Arrhenius 1869 Chain theory of ammonates Blomstrand 1884 Amendments to chain theory Jorgensen 1892 Werner s dream about coordination compounds... 

Despite its initial successes, there were apparent deficiencies in Arrhenius s theory. The electrical conductivities of concentrated solutions of strong electrolytes are not as great as expected, and values of the van t Hoff factor i depend on the solution concentrations, as shown in Table 14.4. For strong electrolytes that exist completely in ionic form in aqueous solutions, we would expect i = 2 for NaCl, i = 3 for MgCl2, and so on, regardless of the solution concentration. 

Hydrogen was recognized as the essential element in acids by H. Davy after his work on the hydrohalic acids, and theories of acids and bases have played an important role ever since. The electrolytic dissociation theory of S. A. Arrhenius and W. Ostwald in the 1880s, the introduction of the pH scale for hydrogen-ion concentrations by S. P. L. Sprensen in 1909, the theory of acid-base titrations and indicators, and J. N. Brdnsted s fruitful concept of acids and conjugate bases as proton donors and acceptors (1923) are other land marks (see p. 48). The di.scovery of ortho- and para-hydrogen in 1924, closely followed by the discovery of heavy hydrogen (deuterium) and... 

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