We recently had an excellent discussion on the sign of the electrode potential of half cells:
https://www.researchgate.net/post/What_do_you_understand_by_the_signs_on_the_electrode_potentials_as_used_in_electrochemistry
Another question which arose in this discussion was a thought experiment: Is it possible to determine the electrostatic sign of a metallic electrode dipping in a solution of its own ions? Take the simplest possible cases of zinc and copper. If we dip a zinc rod in a solution of 1 M Zn2+ solution, what will be the charged state of the zinc rod if it is electrically not in contact with any material? Similarly, what will be electrostatic charge of a single copper rod dipping in 1 M copper solution?
(Electrochemists will recognize that this is related to Nernst's theory of electrolyte solution pressure and Ostwald's dream of measuring absolute electrode potentials)
Thanks for your input.
Thank you Remi. It is very well known that when Zn (in Zn2+, std condition) is connected with hydrogen electrode it acquires an electrostatic negative charge. I was asking about an experimental way to determine the charge of a *single* zinc electrode dipped in its own solution of ions. Yes the solution as a whole is electrically neutral, but the interface of metal to solution is not.
Hi Wahab, in my opinion your question is not so clear, like is not so clear the former discussion.
Indeed the "ELECTROCHEMICAL POTENTIAL" is not directly related to the "ZERO CHARGE POTENTIAL", that was discussed in the previously question. The right answer to your former question was written by Marietta Ilao only, the other user are talking about something that could sound similar but are very different topics.
Here your question seems to be related to the "ABSOLUTE POTENTIAL"... but it is not so clear for me.
Please, let me know what do you mean...
http://en.wikipedia.org/wiki/Absolute_electrode_potential
http://en.wikipedia.org/wiki/Point_of_zero_charge
http://en.wikipedia.org/wiki/Electrode_potential
Hello Andrea, My question is more on the historical and experimental developments of electrochemical concepts from Ostwald's time to date. For the time being, lets not bring in the various shades of potentials used in electrochemistry. Let me try to simplify the question (and the following example is related to Lippmann's electrocapillary phenomenon). Authors of 19th century keep on writing that a mercury drop in contact with sulfuric acid is positively charged. How did they determine the electrostatic charge on the mercury drop? If this can be answered, I guess I will be close to getting the answer to my original question above. Basically, I am looking for an experimental set up.
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P.S. Marietta's reply represents one school of thought (which considers electrode potential signs in terms of thermodynamics). Many established electrochemists consider these signs as invariant and electrostatic. But this topic is not the part of the current discussion.
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