A reaction is only feasible when its emf value is +ve. Why?

Question

If emf is positive that means the reaction is endothermic. But wouldn't it be more natural if the reaction is feasible when emf value is -ve(exothermic) ? I mean, isn't it easier to release energy than to absorb energy...

Answer 1

? Positive emf doesn't mean that the reaction is endothermic (endothermic reactions have ΔH>0).
The criterion for spontaneous reactions is ΔG<0
If you use the Nernst equation you will reach the conclusion that for the reaction you have
ΔG= -nFE
where n the number of electrons participating in the reaction and
F the Faraday constant

So ΔG<0 (and the reaction will be spontaneous) only when E>0 (of course n,F>0).