Jaroslav heyrovsky biography

My watch list My saved searches My saved topics My newsletter Register free of charge. Keep logged in. Login Register. Additional recommended knowledge. To top. About chemeurope. Spectroscopy Apps for Routine Spectrum Analysis. Your browser is not current. Barry Sharpless John B. Yonath Richard F. Salvatore Quasimodo Italy. Philip Noel-Baker United Kingdom.

Emilio G. Nobel Prize recipients Authority control databases. CiNii Scopus Leopoldina. Deutsche Biographie DDB. Hidden categories: Pages using the Phonos extension Articles with short description Short description is different from Wikidata Articles with hCards Pages with Czech IPA Pages including recorded pronunciations All articles with unsourced statements Articles with unsourced statements from January Nobelprize template using Wikidata property P Toggle the table of contents.

Later incorporated into the Academy of Sciences, it has been called the J. In he was elected a foreign member of the Royal Society. The historical connections of polarography with electrocapillarity date from the investigations of G. Lippmann, who set up 3 an electrochemical cell of which the polarizable electrode consisted of a mercury meniscus in a capillary; the nonpolarizable electrode was a large mercury pool at the bottom of the cell.

Lippmann proceeded to examine surface tension alterations of the mercury meniscus under the influence of polarization.

Jaroslav heyrovsky biography

Its changes in elevation proportional to the changes in surface tensionplotted against applied voltage equal to the potential of the polarizable electroderesult in a curve, known as the electricdouble-layer conception, the peak of the curve denotes the potential at which the mercury surface is uncharged. Instead of the rather unrewarding weighing of mercury drops at different potentials, he began to measure the current between the dropping mercury electrode and the large mercury pool which served as a reference electrode.

In due course he created, in polarography, a novel method for the study of electrochemical processes. The position of aluminum in the table of electropotentials was uncertain because the metal, coated with an oxide film, did not yield reproducible measurements. The main problem was to devise a method to prevent the evolution of hydrogen. In fact, he adopted a type of dropping electrode.

Lewis and his co-workers. The significance of this work lay in the success of the American chemists in measuring the ptentials of alkaline metals by means of alkali amalgam electrodes. In their experiments, the the Americans had set up a special apparatus for the preparation and preservation of the dilute amalgam with theamalgam surface at the end of a capilary servi8ng as an electrode.

At first they found that the sodium amalgam surface, when placed in the sodium hydroxideevolved considerable hydrogen. The high overvoltage of hydrogen on a mercury surface makes it possible for a dilute amalgam of a very negative metal to behave as a reversible electrode, because the evolution of hydrogen is almost entirely prevented.

As the applied voltage become greater, the current increased not continuously but in steps, reaching limiting values corresponding to the different cations or other reducible groups in the solution. On plotting the values for voltage and current, he obtained usually S-shaped curves in which the position of the polarographic curve or wave voltage indicated the qualitative composition of the solution and the height of the curve current determined its contents quantitatively.

He said in his Nobel lecture:. The reason why I keep some 38 years to the electrochemical researches with the dropping mercury electrode is its exquisite property as electrode material. Its physical condition of dropping as well as the chemical changes during the passage of the electric current are well defined, and the phenomena displayed at the dropping mercury electrode proceed with strict reproducibility.

Owing to the latter property the processes at the electrode can be exactly expressed mathematically. Highly reproducible results are obtained with a very small amount of solution because the mean current depends only on the applied potential and is independent of time and of the direction of the polarizing voltage. The mechanic at the institute was prepared to supply a Polarograph the production of a polarogram often took over an hour, but the novel arrangement reduced it to fifteen to twenty minutes.

It is noteworthy that with the very first instrument a high sensitivity could be achieved showing depolarizers in a concentration of 10 -5 gram molecules per liter. The nature of the limiting current—that is, the current which, after reaching a maximum value, remains unaffected by an increase in voltage—was considered in some detail. The relationship between the migration and diffusion components of the limiting current were defined and the importance of the latter in practical polarography was explained, resulting in the working out of an equation by D.

It was shown that the depolarizer or some other component in the solution, when adsorbed by the dropping mercury electrode, could cause changes in polarographic currents. An important step in theoretical polarography occurred after the jaroslav heyrovsky biography of the existence of kinetic currents—polarographic currents governed by the rate of the chemical reactions taking place near the electrode.

He visualized the formation of hydrogen molecules in the three steps. These polarographic currents, observed in the presence of substances which act as catalysts, are connected with the accelerated evolution of hydrogen. By the first attempts jaroslav heyrovsky biography made in polarography to use a cathode-ray oscilloscope instead of a galvanometer.

The voltage of the ordinary alternating-current supply was applied to the dropping mercury electrode, and changes of its potential were followed on the oscilloscope. It was in the course of his studies on oscillopolarography that he found it useful to employ the streaming mercury electrode in order to obtain a steady oscillogram.

Polarography is the science of studying the processes occurring arround the dropping-mercury electrode. It includes not only the study of current-voltage curves, but also of other relationships, such as the current-time curves for single drops, potential-time curves, electrocapillary phenomena and the streaming of electrolytes, and the streaming of electrolytes, and its tools include besides the polarograph, the microscope, the string galvanometer and even the cathoderay oscillograph.

Not until about ten years after the first publications did the scientific community outside Czechoslovakia take notice of polarography. A year later he had the opportunity to acquaint a Russian audience with his work when he was invited to attend the Mendeleev centenary in Leningrad. He introduced a several term - course of lectures and practical classes of that subject and with his research students he continued the development of polarographic method.

The instrument slowly and continuously increased or decreased mutual polarity of the electrodes and at the same time recorded photographically the current passing through the solution and electrodes as function of voltage applied to the electrodes.