HOFF, JACOBUS HENRICUS VAN'T

born Aug. 30, 1852, Rotterdam, Neth. died March 1, 1911, Berlin, Ger. Van't Hoff, detail of an oil painting by Helene Bchmann physical chemist and first winner of the Nobel Prize for Chemistry (1901) for work on rates of reaction, chemical equilibrium, and osmotic pressure. After studies in The Netherlands, he worked briefly under August Kekule at Bonn and then in the Paris laboratory of Charles-Adolphe Wurtz, where he met Joseph-Achille Le Bel. In 1874 he and Le Bel, independently of each other, announced a concept that proved to be the cornerstone in the study of the three-dimensional structure (stereochemistry) of organic compounds: the four chemical bonds that carbon can form are directed to the corners of a tetrahedron. This concept helped explain the property of optical rotation. Hoff was professor of chemistry, mineralogy, and geology at the University of Amsterdam (187896). In 1884 he published tudes de Dynamique chimique (Studies in Chemical Dynamics), which contained the principles of chemical kinetics, described a new method for determining the order of a reaction, and applied the laws of thermodynamics to chemical equilibriums. He also introduced the modern concept of chemical affinity. In 1886 he showed a similarity between the behaviour of dilute solutions and gases. Until 1895 he worked on Svante Arrhenius' theory of the dissociation of electrolytes. In 1896 he became professor to the Prussian Academy of Science at Berlin. His studies of the salt deposits at Stassfurt, Ger., contributed to that nation's chemical industry. In 1887 he and the German chemist Wilhelm Ostwald founded the influential Zeitschrift fr physikalische Chemie (Journal of Physical Chemistry).