Electrode Potential: Zinc-Copper E Cell & Plausibility

[Bladibla]

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?

 

[Borek]

Matter of convention.

 

[Gokul43201]

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

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.

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