Consider a system with a "supporting" electrolyte, for example \(\mathrm{CuSO}_{4}\), and a second salt such as a mixture of \(\mathrm{CuSO}_{4}\) and \(\mathrm{Na}_{2} \mathrm{SO}_{4}\). The system now consists of \(\mathrm{Cu}^{2+}, \mathrm{SO}_{4}^{2-}\), and \(\mathrm{Na}^{+}\). Assume that only \(\mathrm{Cu}^{2+}\) can react at the cathode. Hence the flux of \(\mathrm{Cu}^{2+}\) should be assumed to be non-zero, while those of the other species are zero.

Develop an equation to find the diffusion potential developed in this system and the factor by which the \(\mathrm{Cu}^{2+}\) flux is enhanced.