In an attempt to wrap my head around the basics of electrochemistry I'm working my way through Wesley R. Browne's 'Electrochemistry' primer.
With regards to the equilibrium potential of an electrochemical cell he states: "The equilibrium potential is defined as the potential at which the forward and reverse electron transfer rates are equal and the net current flow is zero. ... When the electrode potential is more positive or more negative than the equilibrium electrode potential, the forward and reverse rates are no longer equal and a net current will flow."
My understanding is that the only equilibrium potential possible for a two-electrode electrochemical cell is 0V, as anything above or below 0V will result in the electrons 'wanting' to go to one electrode or the other = a net current.
However, in a three-electrode setup (working electrode, reference electrode and counter electrode) the potential of the working electrode is stated relative to the reference electrode (eg, 'vs Ag/AgCl'). In this setup, would the equilibrium potential of the working electrode be 0V relative to the counter electrode (as it's the counter electrode with which the vast majority of electrons are exchanged) but therefore not 0V relative to the reference electrode and thus you would be correct in stating that the equilibrium potential for working electrode X is (for example) +0.21V vs an Ag/AgCl reference electrode?
Any and all help appreciated!