By Stal G. Mairanovskii
As our wisdom of the mechanism of electrode approaches raises, it turns into progressively more obvious that the kinetic currents first saw via R. Brdicka and through okay. Wiesner within the 1940's are very greatly encountered. Very many electrode seasoned cesses comprise a chemical level. * this is often actual basically of elec trode procedures that contain natural compounds. accordingly, to appreciate the mechanism of electrode strategies and, specific ly, to properly interpret the result of polarographic investiga tions, it is very important understand the features and relationships controlling the chemical reactions occurring on the electrode floor. as a rule, those reactions are considerably diverse from traditional chemical reactions occurring within the bulk of the answer, because the reactions on the electrodes are frequently laid low with the electrical box of the electrode and the adsorption of the par ticipating compounds . the truth that hydrogen ions often participate in the electro chemical aid of natural compounds makes attainable using electrochemical tools, relatively polarography, for the examine of protolytic reactions. those reactions play a tremendous position in natural chemistry: nearly all of reactions of natural compounds in ideas struggle through a degree during which a hydrogen ion is got rid of or additional (see, for instance, [1, 2]). hence, the polarographic learn of protolytic reactions can provide a lot very important details to theoretical natural chemistry.
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Extra resources for Catalytic and Kinetic Waves in Polarography
The height of the wave is governed by the diffusion, iD, and is proportional to the analytical (overall) acid concentration in the solution Cacid = [K] + [HA]. (27) In a certain pH rangl'l in acidic solutions the wave height is independent of the pH. If the pH of the solution is increased beyond this range, the wave height gradually begins to decrease and at the same time a new wave becomes apparent at more negative potentials. This latter wave increases with increasing pH. The sum of the wave heights of both waves usually remains constant and is independent of the pH.
Therefore it was possible to determine the stability constants of cadmium, zinc, and tin complexes formed with nitrilotriacetic acid. In a later investigation  Koryta used the equations derived by Koutecky and Brdicka  and estimated the rate constant (kt) of the dissociation of the cadmium complex formed with nitrilotriacetic acid. He showed, on the basis of the value determined, that in the discharge of cadmium ions in an excess of nitrilotriacetic acid on a streaming electrode (the contact time with the solution is 8 • 10- 4 sec) the kinetic component of the currerit should not play any role .
Both variants of the indirect method given by Rüetschi were used by Nürnberg and co-workers [176-178] for the determination of the dissociation rate constants which they erroneously attributed CURRENTS UMlTED BY THE RA TE OF CHEMICAL REACTION 35 to the dissociation of weak acids. In reality, these authors dealt with the overall rate of transfer of protons from acids present in the solutions to the molecules of the catalyst; this transfer resulted in catalytic hydrogen formation or production of p-nitroaniline, which they used as proton-transfer agent rather than azobenzene.