Can the anode always be considered as having a lower standard electrode potential than the cathode? When I was studying galvanic cells, I found that for a number of reactions, it always appeared that the anode(i.e negative potential) mostly had a lower electrode potential than the cathode. Can we say that this is always true or are there some exceptions?
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By definition, for a cell to be galvanic, you would need the difference $\ce{E^0_(cathode) - E^0_(anode)}$ to have a positive value. So yes, the standard potential for the anode to have a more negative potential than the cathode.
Lower and higher are terms that are best avoided when talking about electrochemistry. More positive and more negative are unambigious.
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1$\begingroup$ This is only true at standard state. One could pick electrodes which do not satisfy the equation E˚(cathode)–E˚(anode)>0, yet still have a galvanic cell by setting the concentrations of each species to make it so that E(cathode) - E(anode)>0. This is the general definition for a galvanic cell. I agree on the nomenclature point though. $\endgroup$ – Sean Doris Feb 26 '16 at 6:53
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$\begingroup$ True. One could turn an electrochemical system that is electrolytic in standard state into a galvanic cell by modifying concentrations. $\endgroup$ – Burak Ulgut Feb 26 '16 at 7:12
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$\begingroup$ Thank you for helping me out but Can you please give me some example to convert electrochemical system that is Electrolytic in chemical state into galvanic cell by modifying concentrations? $\endgroup$ – AAKASH RAJ Feb 29 '16 at 23:58
