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Thermodynamics/Source of Electrons Supply in electrolysis


Dear Sir, I hope you are fine. I am a bit unable to understand the Electrolytic cell, when it is connected to an external power source (that may be a galvanic battery) for electrolysis process (suppose of molten NaCl). This shows and truly means that the battery shall supply the electrons. With the passage of time, this external battery will automatically lose its Zinc anode due to loss of electrons from Zinc atoms and these resulting Zinc positive ions getting dissolved in the Zinc sulphate solution. No if these electron are supplied by the battery only in the process of electrolysis, these where the electrons go and utilized which are released and provided by the negative ion at anode (e.g. Chloride ion in case of NaCl electrolysis), which gets oxidized at the anode of the electrolytic cell (meaning to say that electrons are lost here also). In this process the Na positive ion is reduced at the cathode correspondingly (gaining electrons there) and changes to Na neutral atom and gets deposited. Now I want to understand that the electrons gained by Na ions at cathode are from the battery or from the Chloride ion. If electrons are provided by battery for Na reduction, then where this loss of electrons by Chloride ions is utilized.
Secondly is there any role of the electric current supplied by the external battery in the formation of these ions like the Na positive ions and Cl negative ions during electrolysis of NaCl and similarly in the formation of  H positive ions and OH negative ions during electrolysis of water. If not by the electric current from the external battery, then how these ions are formed.
I would appreciate your valuable response on both points. Regards

Hi Muhammad,

The ions exist as soon as the chlorine  reacts with the sodium to form sodium chloride.
In the crystaline salt they exist as Na+ and Cl- ions.
They exist in solution as these ions also.

The electrodes of a cell push electrons out and one pole and draw them in at the opposite pole to keep the whole process neutral and alowing current to flow. So the battery (cell) is supplying and absorbing the electrons until it is chemically exhausted.

In water H+ ions and OH- ions exist naturally (just like in salt) and are pushed around and under go redox by the cell.

I hope this helps.
Best wishes.


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Thermodynamics, chemistry, chemical reactions, kinetics, chemical reaction safety, dust explosion technology, static electricity. General science.


Over 40 years experience as a practicing thermochemist in industry. Head of the fire and explosion laboratory of a major European chemical company (Ciba-Geigy). Now retired.

Institute of Chemical Engineers. Royal Society of Chemistry.

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