Jacobus Henricus van 't Hoff

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Jacobus Henricus van 't Hoff
Jacobus Henricus van 't Hoff (1899)

Jacobus Henricus van 't Hoff (born August 30, 1852 in Rotterdam , † March 1, 1911 in Steglitz near Berlin ) was a Dutch chemist and the first Nobel Prize winner for chemistry. Van 't Hoff explored the chirality of carbon compounds, the change in physical properties as a function of the number of particles in a solution, the kinetics of chemical reactions and their temperature dependence.

Life

van 't Hoff (left) and Wilhelm Ostwald in the laboratory (1905)

Van 't Hoff's father worked as a general practitioner in Rotterdam. In Rotterdam, the young Henricus attended a “Hoogere Burgerschool” without Latin, which was roughly equivalent to a secondary school in Germany at the time. Van 't Hoff was interested in chemistry from a very early age. After graduating from high school in 1869, he studied technology at the Polytechnic Institute in Delft . After two years he received his degree and the right to study. From 1871 he studied mathematics at the University of Leiden , then chemistry from 1872 under August Kekulé in Bonn and from 1873 under Charles Adolphe Wurtz in Paris . During his studies, van 't Hoff also became interested in philosophy ( Auguste Comte ) and poetry ( Lord Byron , Heinrich Heine ). Even before completing his doctoral thesis, van 't Hoff surprised the professional world with a short article on optical rotation and the stereochemistry of carbon bonds. However, this article was ignored by the specialist colleagues.

In 1874 he received his doctorate from Eduard Mulder at the University of Utrecht with a dissertation on cyanoacetic acid and malonic acid ( Bijdrage tot de kennis van cyaanazijnzuur en malonzuur ). A phase of unsuccessful applications for a university career followed. As an assistant teacher van 't Hoff got an assistant position at the veterinary school of the University of Utrecht in 1876. In 1876 Johann Wislicenus translated van 't Hoff's work on the asymmetric carbon atom into German. The paramount importance of this article was initially not recognized in Germany either.

In 1877, however, he was initially able to transfer to the chemistry department of the University of Amsterdam as a lecturer , and from 1878 he was appointed professor. There he developed simple apparatus and dealt with osmotic pressure . His work The role of osmotic pressure in analogy between solutions and gases , published in 1887, laid the foundations for the determination of the molecular weight of substances in solution. Svante Arrhenius and Wilhelm Ostwald recognized the importance of van 't Hoff's work. Based on his considerations, the ion theory of aqueous solutions ( dissociation ) was developed.

Van 't Hoff and Wilhelm Ostwald founded the journal for physical chemistry in 1887 and together with Walther Nernst they turned the border area between physics and chemistry into an independent science at the end of the 19th century. The main goal was the quantitative assessment of chemical processes with the methods of physics, especially thermodynamics and kinetics. At the suggestion of Ostwald, the first society for the care of the new science was founded in 1894. This was later to honor the world-renowned Physico-chemist Robert Bunsen in German Bunsen Society for Physical Chemistry renamed and awards since 2009 every three years, the Van 't Hoff Prize to outstanding researchers active in physical chemistry.

Now he has received many honors. In 1892 he was elected to the Academy of Sciences in Göttingen , in 1895 to the American Academy of Arts and Sciences , 1901 to the National Academy of Sciences , 1904 to the American Philosophical Society , 1895 to the Russian Academy of Sciences in St. Petersburg and 1905 to the Académie des sciences . In 1896 he followed a call to the Prussian Academy of Sciences (or University of Berlin ) in Berlin and worked there until his death. He dealt with the chemical equilibrium , with new methods for determining the molecular weight and the formation of salts from seawater and the sequence of the deposition of different salt layers at certain temperatures and pressures.

He received the first Nobel Prize in Chemistry in 1901 for his discovery of the laws of chemical dynamics and osmotic pressure in solutions . For his experiments he used the artificial semipermeable membranes developed by the chemist Moritz Traube . In 1903 he was chairman of the Society of German Natural Scientists and Doctors .

Van 't Hoff died of tuberculosis . He was buried in the Berlin cemetery in Dahlem . The honor grave of the city of Berlin is there in field 1.

Scientific work

Monument in Rotterdam
Honorary grave at the Dahlem cemetery in Berlin

Even before he was awarded the doctorate degree, he published the first of his significant contributions to organic chemistry . He explained the phenomenon of optical activity by adopting, in the optically active compounds may be the chemical bonds between the carbon - atoms arranged and its four neighbors spatially so, the carbon atom at the center and the adjacent atoms at the vertices of that tetrahedron are. The four ties must all be different. This arrangement makes it possible for the molecule to exist in the form of two enantiomers , i.e. mirror-inverted structures. The French chemist Joseph Le Bel had the same idea of ​​explaining optical activity independently of him . In this respect, van 't Hoff has decisively further developed stereochemistry .

Avogadro's law for solutions, dissociation theory

Van 't Hoff developed the idea that Avogadro's Law could also apply to solutions. He found that the osmotic pressure of a solution is directly proportional to the amount of a substance dissolved in it. He concluded that with the same osmotic pressure and temperature, the same number of particles would have to be dissolved. He now applied the equation of state (according to Avogadro's law, Boyle-Mariotte's law ) for gases to solutions and was thus able to carry out exact molecular weight determinations.

Van 't Hoff also applied analogous considerations to raising the boiling point and lowering the freezing point , which François Marie Raoult was able to prove purely empirically . This enabled van 't Hoff to estimate molecular weight determinations and molecular sizes of dissolved substances. However, there were deviations from the previous theory with salts (e.g. potassium chloride) compared to cane sugar. The number of particles found for potassium chloride was twice as high as expected from the molecular mass. This finding supported the theory of Svante Arrhenius , who presented his dissociation theory only after van 't Hoff's preliminary work.

A more complex theory to describe the electrolytic solution tension , the electromotive force (EMF) of galvanic elements, was developed by Walter Nernst . This theory also used a description similar to that used for osmotic pressure.

kinetics

Van 't Hoff also made pioneering work in the field of kinetics with Etudes , Studies on Chemical Dynamics (1896). Van 't Hoff investigated the conversion of chloroacetic acid and saponification of ethyl acetate with sodium hydroxide (both bimolecular reactions). However, this was preceded by studies by Ludwig Ferdinand Wilhelmy , Wilhelm Ostwald as well as Cato Maximilian Guldberg and Peter Waage . Wilhelmy made the first kinetic investigations through the action of acids on sugar; the reaction rate was determined with a polarimeter. Wilhelm Ostwald later also dealt with chemical kinetics. The book also examined the temperature dependence of reaction rates. Van 't Hoff's rule , named after van' t Hoff, states that the speed of a chemical reaction doubles when the temperature increases by around ten degrees Celsius . The Van-'t-Hoff factor expresses the molar dissolution behavior of a substance. The van 't Hoff reaction isobar gives the derivation of the logarithm of the thermodynamic equilibrium constants according to the temperature at constant pressure.

Other services

Further areas of work were thermodynamics , in the context of which van 't Hoff defined affinity in 1884 , as well as oceanic salt deposits and geological deposits; here he laid the foundations for halokinesis with Richard Lachmann .

Fonts

  • La chimie dans l'espace . 1875; German: The storage of atoms in space . Braunschweig 1877 ( digitized version and full text in the German text archive )
  • Views on organic chemistry . 3 parts, Braunschweig 1878–1881
  • Etudes de dynamique chimique . 1884; German: Studies on chemical dynamics . 1898
  • Lois de l'équilibre chimique dans l'état dilué, gazeux ou dissous . 1885
  • Lectures on the formation and splitting of double salts . Leipzig 1897
  • Investigations into the formation conditions of the oceanic salt deposits, especially the Staßfurt salt deposit . Berlin 1897
  • Lectures on theoretical and physical chemistry . Braunschweig 1898–1900
  • The laws of chemical equilibrium for the dilute, gaseous or dissolved state. Engelmann, Leipzig 1900, 2nd edition 1915 (van-'t-Hoff'sches law)
    • First in French: Une propriété générale de la matière diluée , in Kongl.Svenska vetenskapsakademiens Handlingar, Volume 21, No. 17, 1886 and in Archives Néerlandaises 1885

dissertation

  • Marlies Dehler: The philosophical-ideological standpoints and the chemical-historical importance of Jacobus Henricus van't Hoff and Svante Arrhenius in the development of physical chemistry , 1981, DNB 820462586 , dissertation HU, Berlin 1981, 146 pages.

literature

Web links

Commons : Jacobus Henricus van 't Hoff  - Album with pictures, videos and audio files

Individual evidence

  1. ↑ "Proposal for expanding the structural formulas currently used in chemistry into space, together with a related comment on the relationship between the optical rotation capacity and the chemical constitution of organic compounds", in Günther Bugge: The book of great chemists. Verlag Chemie, Weinheim 1970, p. 397.
  2. ↑ Life data, publications and academic family tree of Jacobus Henricus van 't Hoff at academictree.org, accessed on February 12, 2018.
  3. ↑ On the historical development of the DBG. (No longer available online.) Archived from the original on August 23, 2017 ; accessed on August 23, 2017 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.bunsen.de
  4. ↑ Van't Hoff Prize. Retrieved August 23, 2017 .
  5. ^ Member History: Jacobus H. Van't Hoff. American Philosophical Society, accessed October 2, 2018 .
  6. ^ Foreign members of the Russian Academy of Sciences since 1724: van 't Hoff, Jacob Hendrik (Jacobus Henricus). Russian Academy of Sciences, accessed March 11, 2020 (Russian).
  7. ↑ Walther Nernst: The electromotive efficiency of the Jonen. In: Journal of physical chemistry. 4, No. 2, 1889, pp. 129-181.
  8. ^ JH van 't Hoff: Studies on chemical dynamics. W. Engelmann, Leipzig 1896.
  9. ↑ Ludwig Wilhelmy: About the law according to which the action of acids on cane sugar takes place . In: Annals of Physics . tape 157 , no. 11 , 1850, pp. 413-428 , doi : 10.1002 / andp.18501571106 .
  10. ↑ Ludwig Wilhelmy: About the law according to which the action of acids on cane sugar takes place . In: Annals of Physics . tape 157 , no. 12 , 1850, pp. 499-526 , doi : 10.1002 / andp.18501571203 .
  11. ↑ Wilh. Ostwald: Studies on chemical dynamics . In: Journal for Practical Chemistry . tape 29 , no. 1 , 1884, p. 385-408 , doi : 10.1002 / prac.18840290139 .
personal data
SURNAME Hoff, Jacobus Henricus van 't
BRIEF DESCRIPTION Dutch chemist
DATE OF BIRTH August 30, 1852
PLACE OF BIRTH Rotterdam
DATE OF DEATH March 1, 1911
Place of death Berlin-Steglitz