http://C:\Users\jason\Desktop\Research Summer 2016\cucl pb.PNG I am currently attempting to use SEA to plate CuCl2- on to the surface of a magneli phase Titanium oxide membrane. I can roughly rationalize the y-axis and how it functions when there is an electrochemical cell (follow OCP), and how to calculate the potential utilizing the Nernst equation, but what if there is no Echem cell? I will dissolve CuCl2 in acid (pH ~ .8) so the window I am aiming for in which my desired species predominates is tight. (I know the Pourbaix diagram is concentration and temperature dependent but I really just seek to understand exactly what the y-axis means) My question is, If I dissolve x amount of CuCl2 in .5 molar HCl, (10mM CuCl2 solution) in a beaker, in ambient conditions, what would the voltage potential of the solution be? Would it just be 0? Do I need to have an Echem cell in order to have any potential at all? Any help is greatly appreciated.