# Electrode potentials

When we work out the E cell of with the electrode potential values of Zinc and copper (for example) Why does a positive E cell value indicate that the reaction is plausible?

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Borek
Mentor
Matter of convention.

Gokul43201
Staff Emeritus
Gold Member
$$- \Delta G^0 = work~done ~at~constant~potential=E^0_{cell} \Delta Q$$
$$\Delta Q = nF$$
$$\implies \Delta G^0 =-nFE^0_{cell}$$

Of course, now this translates to another convention : that a negative free energy change tells you that the reaction is plausible. To make this more intuitive, it may help to go a step further.

$$\Delta G^0 = -RT lnK$$
$$\Delta G^0 < 0 \implies lnK > 0 \implies K > 1$$