What is the equation that relates standard emf to standard reaction Gibbs energy?

The equation that connects the standard electromotive force (emf) to the standard Gibbs free energy change of a reaction is given by the expression E = -Δ_rG° / nF, where E represents the standard emf, Δ_rG° is the standard Gibbs free energy change, n is the number of moles of electrons exchanged in the reaction, and F is the Faraday constant.

In this context, the negative sign indicates that a spontaneous reaction (which has a negative Gibbs energy change) will result in a positive emf. This relationship is fundamental in electrochemistry, as it directly links thermodynamic properties with the electrochemical behavior of reactions.

The other equations presented do not accurately describe the relationship between standard emf and standard reaction Gibbs energy. For instance, E = RTe^Q is not relevant to standard conditions; E = ΔG° /RT does not correctly represent the connection to emf; and E = νFRc misrepresents the equation as it mixes variables without being tied to Gibbs energies.