Electrochemistry

Elektrochemische Dreielektrodenmessanordnung
electro-chemical three-electrode measuring instrument

the electrochemistry is a subsection of physical chemistry, which is concerned with the connection between electrical and chemical procedures. If a chemical reaction is linked with an electric current, then this is an electro-chemical procedure. Eitherthe redox reaction is forced by an electrical tension applied from the outside (electrolysis), or it by the chemical reaction of suitable substances a measurable tension is caused (galvanic element). These tensions are characteristic of the respective reactions andon a scale documented, the electro-chemical electromotive series. The direct electron jump between molecules, ions or atoms, is not an electro-chemical procedure; for the electrochemistry the spatial separation from oxidation and reduction is typical.

Electro-chemical reactions run ina galvanic cell off and always as redox reactions. During the electrolysis and loading an accumulator thereby energy is supplied, when unloading a battery or with current consumption from a gas cell receives one electricity, those with reversible processes to that Reaction enthalpy corresponds. The river arising with such reactions is a characteristic which can be seized easily, which is very valuable as a check. A voltage characteristic is often taken up, which represent the gemessenene river with variation of the tension. The shape of suchCharacteristic depends beside the usual Reaktionsparamter (concentration of the materials involved, temperature, size of the reactive boundary surfaces) also on the speed of the tension change.

The redox procedures crucial for the electrochemistry run off thereby at the phase boundary electrode - electrolyte. One can thereforedefine: Electrochemistry is the science of the procedures at the phase boundary between electron conductor (electrode) and an ion leader (electrolyte).

To table of contents

applicationsthe electrochemistry

  • production of chemical substances
    • reduction from metal salts to the production of unedler metals, particularly by Schmelzelektrolyse, e.g. for the production of lithium, sodium, potassium, calcium, magnesium and aluminum
      the electric current works here as reducing agent.Since the tension can be varied, the reduction strength can be adapted. The electric current is the strongest reducing agent of chemistry, with which also the unedelsten metals can be reduced.
      The electrolytic metal separation is used also in the galvanotechnics.
    • Oxidation of Anions, e.g. from halides, approximately for the production of Fluor and Chlor
    • the electric current permits redox reactions without the addition of reduction or oxidizing agents. Many further redox reactions can be implemented or become therefore electrolytically particularly elegantly only made possible. Mentionedis the electrical fluoridation or the Kolbe electrolysis.

history of the electrochemistry

Luigi Galvani

an important impact for the development of the electrochemistry were the attempts of Luigi Galvani with frog thighs: muscles contracted, ifthey with different metals contact had. Alessandro Volta manufactured 1799 the first functioning battery of the modern times. This was - be enough before the development of the generator - an extremely important current and voltage supply, which made many important discoveries possible, particularly alsothe first representation of the metals sodium, potassium, barium, strontium, calcium and magnesium in the years 1807 and 1808 by Humphry Davy.

Johann William knight supplied important contributions to end with of the eight tenth century about Galvanismus anddesigned a simple accumulator.

Michael Faraday, who created the terms electrode , electrolyte , anode , cathode , anion and cation, discovered 1832 Basic Law of the electrolysis.


1959 received Jaroslav Heyrovský for the development of an electro-chemical analysis procedure, the polarography, the Nobelpreis for chemistry.

Gas cell (operated with alcohol)

already in the years 1887/1894 recognized William Ostwald that efficient gas cells would have to offer an enormous future potential for the power supply. To the important developments of the 20. Century belongs accordingly the development of the gas cell, first particularly for applications in space: For the Apollo program, which led 1969 to the moon-landing, hydrogen gas cells were developed, which supplied also drinkable water for the astronauts. Also in the space shuttleserve hydrogen gas cells for the current supply.

literature

  • Peter W. Atkins, physical chemistry, Wiley VCH, ISBN 3527302360
  • C.H. Hamann, W. Many pass, electrochemistry, Wiley VCH, 3. Aufl. 1998
  • W.Schmickler, bases of the electrochemistry, Springer 1996
  • K.Schwabe, electrochemistry, academy publishing house, Berlin 1974
  • G.Kortüm, text book of the electrochemistry, 4. Edition, publishing house chemistry, Weinheim 1966

see also

Wiktionary: Electrochemistry - word origin, synonyms and translations
 

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