A question from the university course:
Could a redox reaction spontaneously occur among the redox couples $\ce{A_{ox}}/\ce{A_{red}}$ and $\ce{B_{ox}}/\ce{B_{red}}$ within non-standard circumstances if they have the exact same standard reduction potentials? So then, under which conditions?
The lecturer used the Nernst equation as follows for this question:
$$\Delta E = \Delta E^{\circ\prime} + \frac{RT}{zF} \ln{\frac{[\ce{A_{ox}}]}{[\ce{A_{red}}]}} - \frac{RT}{zF} \ln{\frac{[\ce{B_{ox}}]}{\ce{[B_{red}}]}}$$
From my understanding he is calculating the energy that is needed to run the reaction spontaneously, but I don't understand how he came to this equation.
If the reduction potentials of two half-reactions are the same, is it still possible for them to run spontaneously under certain conditions?