I have a problem that in my physics textbook, a source of EMF is just shown as a box having + and - terminals. The inner workings of that box need not be considered. They claim that although there is obviously an electrostatic force Fe due to this separation of charge, it is countered by a force F specific to the source that maintains the potential difference between the terminals, even in the open circuit case. Without F, charge would simply move between the terminals (accelerated by Fe), and the potential difference would be eliminated. My question is, isn't this claim that the potential difference between the terminals is maintained in an open circuit situation false in the case of an electrochemical cell? Here's why I think so. In an open circuit situation (battery is not in use and not connected to anything), the redox reaction can't occur in the first place because the anode is not physically in contact with the oxidising agent (the cathode) so what the hell could possibly be oxidising it? Hence, neither the + nor the - terminal is actually charged, so the potential difference is zero. If I'm wrong, can you please explain why? It doesn't make sense to me that we can have a sustained redox reaction occurring in a battery that's just sitting there.