Jacobus Henricus van 't Hoff

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Jacobus Henricus van 't Hoff
Dutch chemist
Born	August 30, 1852 Rotterdam, Netherlands
Died	March 1, 1911 Steglitz, Berlin, Germany

Jacobus Henricus van 't Hoff (August 30, 1852 - March 1, 1911) was a Dutch physical and organic chemist and the winner of the inaugural Nobel Prize in chemistry. His research on chemical kinetics, chemical equilibrium, osmotic pressure and crystallography is credited to be his major work. Van 't Hoff helped to found the discipline of physical chemistry as we know it today.

Early days

He was born in Rotterdam, one of seven children of a medical doctor, Jacobus Henricus van 't Hoff, and Alida Jacoba Kolff. From a young age he was interested in science and nature; he frequently took part in botanical excursions, and his receptiveness for philosophy and his predilection for poetry were already apparent in his early school years. (Lord Byron was his idol.)

His early education was taken in the Realschule in Rotterdam. When he was 17, against the wishes of his father, he went to study chemistry at the Delft Polytechnic Institute. He completed the three year course there in two eyars, and when he was 19, he enrolled at the University of Leiden, remaining there for a year, after which studied inBonn, Germany with Friedrich Kekulé), then in Paris with C. A. Wurtz). He returned to Holland, finally receiving his doctorate at the University of Utrecht in 1874 at age 22.

It was while he was at Utrecht that he created an upheaval in chemistry by proposing a three dimensional model for the structure of a class of carbon compounds. He shares credit for this idea with the French chemist Joseph Le Bel, who independently came up with the same idea at about the same time.

Van't Hoff later expanded this idea to account for optically active carbon compounds that affect a beam of light passing through them in a characteristic way. These discoveries opened the way for the new science of stereochemistry, which studies the three-dimensional arrangement of atoms in a chemical compound.

In 1876, Van't Hoff went to Utrecht to teach physics at the veterinary college there. In 1877, he lectured at the University of Amsterdam, and became a full professor there the following year, a post he would retain until 1896. In 1878 Van 't Hoff married Johanna Francina Mees. They had two daughters, Johanna Francina (b. 1880) and Aleida Jacoba (b. 1882), and two sons, Jacobus Hendricus (b. 1883) and Govert Jacob (b. 1889).

In 1884, van't Hoff published his research on chemical kinetics, naming it Studies in Chemical Dynamics. In this work, he shows the relationship between the concentration of compounds in a chemical reaction and the rate at which the reaction proceeds. He was also able to show how the science of thermodynamics can be applied to chemical equilibrium, where a chemical reaction that proceeds in two directions comes to a standstill. Van't Hoff also discusses the speed of a chemical reaction in its relation to temperature.

In 1885 he was appointed member of the Royal Netherlands Academy of Sciences.

In 1886, van't Hoff published a series of papers in which he showed that the same laws that apply to gases can be used to understand the behavior of solutions. This also enabled him to apply the principles of thermodynamics to solutions.

Van't Hoff's findings did not, however, apply to electrolytes—chemicals like salt that are believed to break up into electrically charged portions called ions upon entering a solution. This part of chemistry he left for Svant Arrhenius to provide the solution for a few years later.

In 1887 he and German chemist Wilhelm Ostwald founded an influential scientific magazine named Zeitschrift für physikalische Chemie ("Journal of Physical Chemistry").

Until 1895 he worked on Arrhenius's theory of the dissociation of electrolytes. On 1896 he became professor to the Prussian Academy of Science at Berlin. His studies of the salt deposits at Stassfurt contributed to Prussia's chemical industry. In these, he was able to apply results established in the laboratory to draw conclusions about the formation of salt deposits over geologic epochs.

In 1896, he was invited to take a professorship at the University of Berlin, where he was elected into the membership of the Imperial Academy of Sciences. In Berlin his teaching duties only required him to lecture once a week. The rest of his time was spent at a research facility provided by the academy. Van't Hoff was elected as a foreign member of the Royal Society of London in 1897.

In 1901 he received the first Nobel Prize in chemistry for his work with solutions.

Other distinctions included the honorary doctorates of Harvard and Yale 1901, Victoria University, Manchester 1903, Heidelberg 1908; the Davy Medal of the Royal Society 1893 (along with Le Bel), Helmholtz Medal of the Prussian Academy of Sciences 1911; he was also appointed Chevalier de la Legion d'Honneur 1894, Senator der Kaiser-Wilhelm-Gesellschaft (1911). Van't Hoff was also honorary member of the British Chemical Society in London, the Royal Academy of Sciences, in Göttingen 1892, American Chemical Society 1898, and the Académie des Sciences, in Paris 1905.

Van 't Hoff died at the age of 58, on March 1, 1911, at Steglitz near Berlin.

Van't Hoff in 1900s.

File:J.H. van 't Hoff.gif

Van 't Hoff in the 1900s at the height of his career.

Stereochemistry

Methane was known to consist of four atoms of hydrogen and one of carbon. It had also been determined that it was a symmetrical compound, meaning that in chemical reactions, other chemicals did not discriminate as to which hydrogen atom they would react to. Van't Hoff quickly concluded that the only spacial arrangement consistent with this finding was one where the carbon atom lay at the center of a regular tetrahedron (a four-sided geometrical figure consisting of four equilateral triangles) with each of the other four molecules at a corner of the tetrahedron. This was the first peek that scientists had ventured to take into the three-dimensional structure of molecules.

Van't Hoff claimed as the inspiration for his discovery, Johannes Wislicenus's studies on lactic acid, in which he declares that differences in some chemical properties may be attributable to structural differences in their molecules. On the other hand, Joseph Achille Le Bel, who, incidentally, had studied with van't Hoff under Kekule, and who published a similar conclusion to van't Hoff, claimed Louis Pasteur as his inspiration.

Another mystery confronting chemists at the time was the optical properties of different substances in solution. A beam of light is said to be polarized when, according to the wave theory, all the waves are in the same plane. Jean-Baptiste Biot had established long ago that when a beam of polarized light passes through the solutions of some organic compounds, the plane of polarization of the light is rotated, sometimes to the right, sometimes to the left. He postulated that this could be due to the lack of symmetry in the structure of the molecules, meaning that the molecules must have a left-hand and right-hand side that are distinguishable from one another. Louis Pasteur surveyed a large number of substances that exhibit this property, and found that they all consisted of a carbon atom surrounded by atoms of more than one element. Van't Hoff showed how his stereochemical model of carbon compounds could account for this property.

Legacy

Van't Hoff was the first chemist to peer into the three dimensional structure of molecules. His work led, some 60 years later, to the discovery of the three dimensional structure of proteins and to deciphering the winding staircase-like structure of the DNA molecule.

Van't Hoff's exploration of the factors that drive the speed of chemical reactions were of major importance to the chemical industry. They also form the basis for the education of chemistry students who must calculate the speed of a reaction based on the concentration of the reactants.

Van't Hoff studied the lives of famous scientists, and concluded that imagination plays an all-important role in the ability of a researcher to make new discoveries.

Based on his discoveries and those of Arrhenius, Ostwald, Williard Gibbs and a handful of other scientists, the field of physical chemistry was born.

See also

• Van 't Hoff factor
• Van't Hoff equation
• Wilhelm Ostwald

References

ISBN links support NWE through referral fees

• Forsén, Sture, ed. 1999. Nobel Lectures in Chemistry.

London: World Scientific Publishing Coo. ISBN 9810234058.

• Jones, Harry C. 1911. Jacobus Henricus van 't Hoff. Proceedings of the American Philosophical Society. 50: iii-xii.
• Methods and Styles in the Development of Chemistry By Joseph Stewart Fruton

External links

• The Nobel Prize in Chemistry 1901. Retrieved May 3, 2007.

Nobel Prize in Chemistry: Laureates (1901-1925)

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