Eperimental studies of V.Ostwald and J.van Hoff

1. Eperimental studies of V.Ostwald and J.van Hoff By: Stela Bachkova

2. Friedrich Wilhelm Ostwald • Friedrich Wilhelm Ostwald (Latvian: Vilhelms Ostvalds; 2 September 1853 – 4 April 1932) was a Baltic Germanchemist. He received the Nobel Prize in Chemistry in 1909 for his work on catalysis, chemical equilibria and reaction velocities. Ostwald, Jacobus Henricus van 't Hoff, and Svante Arrhenius are usually credited with being the modern founders of the field of physical chemistry.

3. Wilhelm Ostwald

4. Early years • Ostwald was born ethnically Baltic German in Riga, to master-cooper Gottfried Wilhelm Ostwald (1824–1903) and Elisabeth Leuckel (1824–1903). He was the middle of two brothers, Eugen (1851–1932) and Gottfried (1855–1918). Ostwald graduated from theUniversity of Tartu, Estonia, in 1875, received his Ph.D. there in 1878 under the guidance of Carl Schmidt, and taught at Co-Arc from 1875 to 1881 and at Riga Polytechnicum from 1881 to 1887.

5. Career and research • Wilhelm Ostwald is usually credited with inventing the Ostwald process (patent 1902), used in the manufacture of nitric acid, although the basic chemistry had been patented some 64 years earlier by Kuhlmann, when it was probably of only academic interest due to the lack of a significant source of ammonia. That may have still been the state of affairs in 1902, although things were due to change dramatically in the second half of the decade as a result of Haber and Bosch's work on their nitrogen fixingprocess (completed by 1911 or 1913). The date 1908 (six years after the patent) is often given for the invention of the Ostwald process, and it may be that these developments motivated him to do additional work to commercialize the process in that time-frame. Alternatively, six years might simply have been the bureaucratic interval between filing the patent and the time it was granted.

6. The combination of these two breakthroughs soon led to more economical and larger-scale production of fertilizers and explosives, of which Germany was to find itself in desperate need during World War I. Ostwald also did significant work on dilution theory leading to his discovery of the law of dilution which is named after him. Ostwald's rule concerns the behaviour of polymorphs. The word mole, according to Gorin, was introduced into chemistry around 1900 by Ostwald. 

7. Ostwald defined one mole as the molecular weight of a substance in mass grams. The concept was linked to the ideal gas, according to Ostwald. Ironically, Ostwald's development of the mole concept was directly related to his philosophical opposition to the atomic theory, against which he (along with Ernst Mach) was one of the last holdouts. He explained in a conversation with Arnold Sommerfeld that he was converted by Jean Perrin's experiments on Brownian Motion.

8. Ostwald was a member of the International Committee on Atomic Weights. As a consequence of World War I this membership ended in 1917 and was not resumed after the war. The 1917 Annual report of the committee ended with the unusual note: "Because of the European war the Committee has had much difficulty in the way of correspondence. The German member, Professor Ostwald, has not been heard from in connection with this report. Possibly the censorship of letters, either in Germany or en route, has led to a miscarriage".

9. In addition to his work in chemistry, Wilhelm Ostwald was very productive in an extremely broad range of fields. His published work, which includes numerous philosophical writings, contains about forty thousand pages. Ostwald was also engaged in the peace movement of Berta von Suttner.

10. Among his other interests, Ostwald was a passionate amateur painter who made his own pigments, and who developed a strong interest incolor theory in the later decades of his life. He wrote several publications in the field, such as his Malerbriefe (Letters to a Painter, 1904) andDieFarbenfibel (The Color Primer, 1916). His work in color theory was influenced by that of Albert Henry Munsell, and in turn influencedPaul Klee and members of De Stijl, including Piet Mondrian. He was also interested in the international language movement, first learningEsperanto, then later becoming an Idist.

11. Ostwald adopted the philosophy of Monism as advanced by Ernst Haeckel and became President of the Monistic Alliance in 1911. He used the Alliance's forum to promote Social Darwinism, eugenics and euthanasia. Ostwald's Monism influenced Carl G. Jung's identification of psychological types. • He was one of the directors of the Die Brücke institute in München. The institute was sponsored, significantly, from Ostwald's Nobel Prize money.

12. Jacobus Henricus van ’t Hoff, • (born Aug. 30, 1852, Rotterdam, Neth.—died March 1, 1911, Berlin, Ger.), Dutch physical chemist and first winner of the Nobel Prize for Chemistry (1901), for work on rates ofchemical reaction, chemical equilibrium, and osmotic pressure.

14. Education and early career • Van ’t Hoff was the son of a physician and among the first generation to benefit from the extensive Dutch education reforms of the 1860s. He attended the newly formed HoogereBurgerschool (High School) in Rotterdam. These new schools emphasized the study of mathematics and science to prepare students for a career in the growing industrial economy of the Netherlands. Beginning in 1869, van ’t Hoff studiedchemistry at the Technical University in Delft and mathematics and physics at the University of Leiden before traveling to Germany to study chemistry with August Kekule at the University ofBonn and then France to study chemistry with Charles-AdolpheWurtz at the École de Medicine. He finally returned to the University of Utrecht to complete his doctoral dissertation in 1874.

15. Before he completed his dissertation, van ’t Hoff published an 11-page pamphlet in which he proposed that if the four bonds (or valence electrons) of thecarbonatom pointed toward the corners of a tetrahedron, it would explain some puzzling cases of isomerism and also explain why solutions of certainchemical compounds would rotate a plane of polarized light. His theory is today one of the fundamental concepts in organic chemistry and the foundation of stereochemistry, or the study of the three-dimensional properties of molecules. This idea was also published independently, in a slightly different form, by the French chemist Joseph Achilles Le Bel, whom van ’t Hoff had met during his stay in Wurtz’s laboratory earlier in the year. • Despite this innovative pamphlet, van ’t Hoff’s future in science was uncertain until he was appointed in 1876 to a new position lecturing chemistry and physics at the Imperial Veterinary College in Utrecht. In 1878 he was appointed professor of chemistry, mineralogy, and geology at the newly created University of Amsterdam.

16. Birth of physical chemistry • In the late 1870s, van ’t Hoff turned away from organic chemistry and became interested in explaining why various chemical reactions occur at widely different rates. In 1884 he published the innovative book Études de dynamiquechimique (“Studies in Chemical Dynamics”), in which he used the principles of thermodynamics to provide a mathematical model for the rates of chemical reactions based on the changes in the concentration of reactants with time. In the Études, van ’t Hoff showed how the previously independently developed concepts of dynamic equilibrium (that chemical equilibrium results when the rates of forward and reverse reactions are equal), the law of mass action (that the concentration of substances affects the rate of reaction), and the equilibrium constant (the ratio of the concentrations of 

17. starting materials to products at equilibrium) together formed a coherent model for understanding the nature of chemical reactions. Finally, he showed mathematically how temperature, pressure, and mass affected the rate of chemical reactions and how the heat generated by a reaction could be calculated from the mathematical equation governing the finalequilibrium state. This relationship between heats of reaction and equilibrium allowed van ’t Hoff to define chemical “affinity,” an old concept in the history of chemistry that had been difficult to define in terms of its effects, specifically the amount of work that a reversible chemical reaction could perform.

18. One of the central assumptions van ’t Hoff made in the Études was that the behaviours of gases and solutions were analogous, and in a series of papers published in 1886 and 1887 he set out to justify that assumption by modeling the behaviour of dilute solutions, using the principles of thermodynamics. He showed that osmotic pressure, the tendency of a pure solvent to cross a semipermeable membrane to dilute a solution on the opposite side, was directly proportional to the concentration of the solution and could be modeled by the same equation (the perfect gas law) that governed the behaviour of ideal gases.

19. In 1887 van ’t Hoff and the German chemist Wilhelm Ostwald founded the ZeitschriftfürphysikalischeChemie (“Journal of Physical Chemistry”) as a forum for the new physical chemistry based on thermodynamics that he, Ostwald, and the Swedish chemist Svante Arrhenius had created during the 1880s. On the basis of his innovative and successful treatment of chemical affinity, van ’t Hoff was awarded the first Nobel Prize for Chemistry in 1901.

20. Van ’t Hoff accepted an appointment in 1896 to the Academy of Sciences in Berlin, where he turned to another problem in chemical equilibrium—the conditions under which salt deposits are formed in the ocean, specifically the salt deposits at Stassfurt, Ger. In order to understand the conditions behind the precipitation of salts, van ’t Hoff modeled the deposition process as an equilibrium between the solution and solid phases of the components in water at a constant temperature. This work was published in 1905 and 1909 as the two-volume ZurBildungderozeanischenSalzablagerungen (“On the Formation of Oceanic Salt Deposits”). Van ’t Hoff died in 1911 of pulmonary tuberculosis shortly after completing this work.