My background: I've read several books and articles on electrochemistry and even do photoelectrochemical research in a lab, so I'm somewhat familiar with the concepts and techniques.
In texts on electrochemistry, the standard reduction potential and its meaning is usually axiomatically presented early on and everything follows from there. What I would like to see in a treatment of the subject is an explanation of how the chemical equations of the reduction half reactions are actually determined. For example, let's take the equation $\ce{Cu^{2+} + 2e- <-> Cu}$. How did they figure out that it is in fact two electrons reducing the $\ce{Cu^{2+}}$ ion?
One could do open circuit potential measurements to determine the standard reduction potential, but it would seem to me that you would have to know the ionic state of the element a priori to use this technique. One could also apply a voltage until the reaction "turns on" then approximate that onset voltage as the standard reduction potential, but this wouldn't be strictly true as it would be a non-equilibrium measurement and would also be subject to the kinetics of the surface. Does anyone know of a book or other treatment showing how the chemical equations are determined or better yet has experience doing this?