Transcript Eperimental studies of V.Ostwald and J.van Hoff

By: Stela Bachkova
Friedrich Wilhelm Ostwald
 Friedrich Wilhelm Ostwald (Latvian: Vilhelms
Ostvalds; 2 September 1853 – 4 April 1932) was a Baltic
German chemist. 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.
Wilhelm Ostwald
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.
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
fixing process (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.
 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.
 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.
 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".
 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.
 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) andDie Farbenfibel (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.
 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.
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.
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 Hoogere
Burgerschool (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-Adolphe Wurtz at the École de
Medicine. He finally returned to the University of Utrecht to
complete his doctoral dissertation in 1874.
 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 thecarbon atom 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.
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 dynamique
chimique (“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
 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.

 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.

 In 1887 van ’t Hoff and the German chemist Wilhelm
Ostwald founded the Zeitschrift für physikalische
Chemie (“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.

 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 Zur Bildung der ozeanischen
Salzablagerungen (“On the Formation of Oceanic Salt
Deposits”). Van ’t Hoff died in 1911 of pulmonary
tuberculosis shortly after completing this work.