# Negative ions affecting galvanic cell voltage

I don't see why negative ions don't affect the voltage. I mean the electric field of a negative ion like $\ce{SO4^{-2}}$ is not like what $\ce{NO3-}$ produces that means that it should affect the overall voltage.

This is the same reason why for example for $\ce{Cu+^2}$ the reduction electrode potential is higher than for $\ce{Zn+^2}$

• What reaction? How is the cell constructed? Need some more information here in order to answer. – Burak Ulgut Jan 10 '17 at 7:55

Well, assuming that you're talking about an aqueous cell, in order to get the anion into solution, you need a salt: eg $\ce{CuSO4}$ or $\ce{Cu(NO3)2}$. Yes, the local electric field around a single $\ce{SO4^2-}$ anion would be stronger than around a single $\ce{NO3^-}$. However, at the same concentration of $\ce{Cu^2+}$ you would have twice as many $\ce{NO3^-}$ ions so the overall solution would still be neutral.
I don't see how this explains the difference in potential of $\ce{Cu^2+/Cu}$ vs $\ce{Zn^2+/Zn}$ since both have the same charge.