Hans Max Jahn

Hans (Johannes) Max Jahn (born July 4, 1853 in Küstrin ; † August 7, 1906 in Berlin ) was a German chemist , physical chemist and university professor .

Live and act

Jahn first studied chemistry , physics and mathematics at the University of Heidelberg before he switched to August Wilhelm von Hofmann at the Friedrich-Wilhelms-Universität Berlin , who hired Jahn as a private assistant and with whom Jahn also wrote a dissertation on the derivatives of secondary octyl alcohol in 1875 earned his doctorate.

He then traveled to Greece at the University of Athens , where he shortly appointed professor received a chair. But as early as 1877 he turned his back on Athens and worked with Ernst Ludwig at his Vienna laboratory at the Vienna Commercial Academy with tannins , the analysis of Thermopylae spring water, with chemical reactions of the decomposition of ethanol and the vapor density of bromine, and where he lectured as a private lecturer .

It was the time when electricity-generating experiments led more and more to practical results, with the British Michael Faraday and James Clerk Maxwell , among others, making a name for themselves as well as Oskar von Miller , who was supposed to have succeeded in the first direct current transmission from Miesbach to Munich in Germany this list should not be forgotten. It was obvious that Jahn would also be interested in this part of the technical field and question possible applications for chemistry. In 1884 he found a congenial partner in Leopold von Pebal at the University of Graz , with whom he can definitely be called one of the pioneers of electrochemistry . With his research on the interactions of electrochemistry on the one hand and thermodynamics on the other, Jahn succeeded in proving the validity of the second law of thermodynamics and Joule's law for electrolytes . Jahn gained important experience during this research on the interlinking of chemical and electrical energy in galvanic cells . As a “by-product”, Jahn also expanded his considerable knowledge of thermoelectricity with his work, and incidentally underpinned the theory of the Gibbs-Helmholtz equation .

In 1889 Jahn moved back to Berlin where he took on a professorship at the Agricultural University Berlin and continued his electrochemical experiments and research at the institute headed by Hans Heinrich Landolt . His focus was on the reactions of polarized light in liquids, the mole fraction , latent heat of vaporization and electrolytic dissociation . Around 1900 he got into a dispute with Max Planck , Walther Nernst and Svante Arrhenius when he tried to modify his equation but was not as successful as usual.

One of Jahn's legacies in his textbooks and lectures was the need for mathematical penetration into chemistry, as well as the services he has earned for the recognition of the entropy concept.

Works

• Jahn, M .: Contribution to the knowledge of the secondary octyl alcohol (Diss.). Berlin, Publisher: Schade, 1875
• Jahn, M .: The principles of thermochemistry and their significance for theoretical chemistry . Vienna, Publisher: Hölder, 1882.
• Jahn, M .: Electrolysis and its significance for theoretical and applied chemistry . Vienna, Publisher: Hölder, 1883
• Jahn, M .: Outline of electrochemistry . Vienna, Publisher: Hölder, 1895
• Jahn, M .: About the electromagnetic rotation of the polarization plane in liquids, especially in salt solutions . Meeting reports of the Royal Prussian Academy of Sciences in Berlin, 1891.1, pp. 237–259.
• Jahn, M., Landolt, H .: About the molecular refraction of some simple organic compounds for rays of infinitely great wavelength . Meeting reports of the Royal Prussian Academy of Sciences in Berlin, 1892,2, pp. 729–758.

Individual evidence

1. ^ Hans-Georg Bartel: Jahn, Hans Max , Lexicon of important natural scientists, 2007, Volume 2; Elsevier GmbH, Munich; P. 273; ISBN 3-8274-1883-6
2. ↑ Hans Max Jahn. Prabook, 1973, accessed March 6, 2020 .