# How can you have a reduction potential for a non redox reaction?

The standard reduction potential for the half cell $$\ce{FeCO3_{(s)} + 2e- <=> Fe_{(s)} + CO3^2-} \quad\quad(E^o =-0.756 \text{V})$$ and the standard reduction potential for the half cell $$\ce{Fe^2+ + 2e- <=> Fe_{(s)}}\quad\quad\quad\quad\quad\quad (E^o = -0.44 \text{V})$$ are as given.

From these, I calculated the $$\ce{E^o}$$ for the reaction $$\ce{FeCO3_{(s)} <=> Fe^2+ + CO3^2-}\quad\quad(E^o = -0.31 \text{V})$$ How do I interpret this number because the dissolution is not a redox reaction? How do I calculate $$\Delta G^o$$ for the reaction since $$n = 0$$ in the dissolution reaction ($$\Delta G^o=-R*T*\text{ln}(K)$$ will not work)?

• What? Where is Fe (0)? – Alchimista Jan 1 at 9:23
• @Alchimista In the dissolution reaction, Fe stays in the +2 oxidation state on both sides of the equation so n = 0. – Cyclopropane Jan 1 at 13:04
• I don't get it then... It is like wanting the circumference of a square or even worse. – Alchimista Jan 2 at 8:27