what was the justification for the use the cathode and anode terminology in IEF?
There is no redox taking place in IEF, just proteins interacting with an electric field
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Who was responsible for this naming system and how can we change it?
Michael Faraday was responsible for the terms anode and cathode more than hundred years ago.
All the confusion regarding the nomenclature will vanish if you do not associate electrostatic signs with these two terms. One should identify the electrode labels with the redox processes rather than the signs.
- Cathode: The electrode where reduction occurs
- Anode: The electrode where oxidation occurs
These definitions are true whether you have a electrolytic or galvanic cell. This eliminates the need to call the negatively charged electrode as a cathode in an electrolytic cell or the positively charged electrode as the cathode in the galvanic cell. These definitions are self-consistent and hence nobody bothered to changed them.
Isoelectric focusing is "sort" of an an electrolytic "cell" hence its cathode is has a electrostatic negative sign because if we were to remove this gel and replace it with just salt water, we will see hydrogen evolution (= reduction of water) at this electrode.
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1$\begingroup$ thanks for the answer, I still dont understand why we use that terminology in IEF, there is no oxidation or reduction taking place, just interaction with an electric field. How can oxidation (loss of negatively charged electrons) result in anything other than a positive charge? the two things seem very closely intertwined $\endgroup$ – Robertthebraveofnanog Oct 7 '19 at 1:49
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1$\begingroup$ Yes, as I said if you dip the same two electrodes used in IEF in an aqueous salt solution (i.e., remove the gel), you would see reduction occurring at the electrode with a negative charge. Therefore that electrode is the cathode. $\endgroup$ – M. Farooq Oct 7 '19 at 1:54
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$\begingroup$ I think the point of confusion for me is that to my understanding electolysis requires an electrical current to drive a reaction that is non-spontaneous (putting electrons on a negative species) are you saying that the cathode and anode used in IEF is made via electrolysis? I appreciate you taking the time to engage in conversation with me on this $\endgroup$ – Robertthebraveofnanog Oct 7 '19 at 2:08
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1$\begingroup$ Think of it this way: There are two electrodes X and Y in isoelectric focussing. $Disconnect$ the leads and let us say you dip these electrodes in a salt water. If electrode X shows evolution of hydrogen, you will call electrode X, the cathode. If electrode X shows oxygen, you will label electrode X as the anode. $\endgroup$ – M. Farooq Oct 7 '19 at 14:12
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1$\begingroup$ Okay now I get it. Thank you very much. this is why you called IEF "sort of" an electrolytic cell. the cathode and anode are analogous, but bc of the gel they dont change $\endgroup$ – Robertthebraveofnanog Oct 7 '19 at 18:01
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The good mnemonic tool to remember is :
Anode = anabasis, electrons would be going upwards from the electrode to the wire = oxidation, ( Xenophon, Anabasis, 404BC, "The journey upwards(to north))
Cathode = cathabasis(the journey downwards), electrons would be going downwards from the wire to the electrode = reduction
That means a cathode/anode is the electrode where reduction/oxidation occurs, what means the flipped signs for a cell being a source/recipient of energy.
A cathode is:
- the negative electrode during electrolysis ( electrons going down the wire, causing reduction)
- the positive electrode during the cell provision of electricity( electrons going down the wire, causing reduction)
And vice versa for an anode.
Anabasis/catabasis has application in other domains as well. E.g. ababatic/cathabatic processes in synoptical meteorology are processes related upward/downward convection of air,like at the front and the back side of the cold front of the 2nd kind.
