Van’t Hoff’s theory

In Planck s investigation of equilibrium in dilute solutions, the law of Henry follows as a deduction, whereas in van t Hoff s theory, based on the laws of osmotic pressure ( 128), it must be introduced as a law of experience. The difference lies in the fact that in Planck s method the solution is converted continuously into a gas mixture of known potential, whilst in van t Hoff s method it stands in equilibrium with a gas of known potential, and the boundary condition (Henry s law) must be known as well. Planck (Thermodynamik, loc. cit.) also deduces the laws of osmotic pressure from the theory. 

An interesting account and references to van t Hoff s early work can be found in The Reception of J. H. van t Hoff s Theory of the Asymmetric Carbon by H. A. M. Snelders, J. Chem. Educ. 51, 2 (1974). A century has passed since van t Hoff first published his theory, which he did-before he obtained his doctoral degree from the University of Utrecht, van t Hoff was the first recipient of the Nobel Prize in chemistry (1901) for his later work in thermodynamics and chemical kinetics. 

There is a brief description of the development of the physical chemistry of non-aqueous solutions from 1920 to 1985184 and an analysis of van t Hoff s theory of diluted solutions.185 186 The role of the chemist Paul Walden (1863-1957) in the development of theories about chemical solutions has been discussed.187 Amedeo Avogadro s (1776-1856) research on the nature of metal salts has been examined.188 There is, also, a discussion of Thomas Graham s (1805-1869) work on the diffusion of gases and liquids.189... 

But why did this curious rule subsist In van t Hoff s theory, every carbon atom in every organic molecule can be conceived as occupying... 

Van t Hoff s theory offered an explanation for many hitherto mysterious cases of "absolute isomerism," including that of the two acids from wine tartar and the two lactic acids. The theory also validated and made sense of Pasteur s work of 1848 and his speculative notions of 1860. The first publication of the theory was in a self-published twelve-page Dutch pamphlet, dated 5 September 1874 and printed immediately thereafter a French translation of the pamphlet appeared almost simultaneously in a relatively obscure Dutch journal. Two months later (5 November 1874), van t Hoff s former labmate in Wurtz s research group, LeBel, published a substantially similar theory in the Bulletin de la Societe Chimique. There has never been any evidence that either man knew of the other s work in advance of his own publication. Since van t Hoff had published his theory so obscurely, it was in LeBeTs paper that most chemists first read of these ideas. But because LeBeTs... 

Snelders, H. "The Reception of J. H. van t Hoff s Theory of the Asymmetric Carbon Atom." Journal of Chemical Education 51 (1974) 2-7. 

The chemical evidence was misleading and Wislicenus, on the basis of van t Hoff s theory, showed that the two crotonic acids are geometrical isomers (see p. 757) and both have the same constitutional formula, CH3—CH=CH—COOH. 

Van t Hoff s theory of solutions was based on the phenomenon of osmotic pressure, some account of which will first be given. The purification of salt by putting it in an ox-bladder, and immersing this in water, which penetrates the bladder and forms a solution of salt, which is then evaporated, is described in a work of 1529. Van Helmont found that salt passes with water through a bladder, and so explained the passage of food (chyle) through the walls of the intestines. 

On 5 November 1874 a loj page paper was presented to the Paris Chemical Society by Le Bel. His treatment is more general and abstract than van t Hoff s and is not illustrated by figures, but the results are practically the same. Van t Hoff s theory was attacked by Kolbe, who thought it would be impossible to form a picture of the arrangement of atoms in space. Van t Hoff says ... 

Wislicenus at once accepted van t Hoff s theory (1874) and contributed an introduction to the German translation of van t Hoff s book (1877). He was mildly rebuked by Kekule, and violently by Kolbe, for his support of van t Hoff s theory. The theory was also adopted by Roscoe and Schorlemmer. ... 

At the outset it was said that both kinetics and electrochemistry, unlike thermodynamics, had a healthy and vigorous childhood. At the same time it should be recognized that at first investigators in physical chemistry tended to be treated as pariahs by the majority of chemists. Van t Hoff suffered a period of unemployment at the beginning of his career, and Ostwald at first had to work as a schoolteacher with no facilities for research. Van t Hoff s theory of the tetrahedral carbon atom was derided by the organic chemist Hermann Kolbe (1818-1884). Ostwald s important early work in physical chemistry was not at all appreciated by many chemists, who complained that Ostwald was not a true chemist since he had discovered no new compounds to this Ostwald cheerfully retorted that the number of compounds that he had discovered was minus one, since he had shown by physical methods that an alleged new compound was identical with a substance that was already well known. 

The Phase Rule — Theory of Solutions — Supersatured Solutions — Freezing-Points of Solutions — Raoult — Vapour Pressure Lowering — Osmotic Pressure — Van t Hoff s Theory of Solutions — Van t Hoff — Chemical Kinetics — Abegg. Tammann. 

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

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