[LHM]

 :delta: E^o is measured at constant volume and  :delta: H^o is measured at constant pressure. For the reaction:
2C(s) + O₂(g)  2CO(g)  :delta: H^o<0 kJ
How do the  :delta: E^o and  :delta: H^o compare for this reaction?
A)  :delta: E^o <  :delta: H^o
B)  :delta: E^o > :delta: H^o
C)  :delta: E^o =  :delta: H^o
D) Impossible to tell from this information.

I know that  :delta: G^o=-nFE^o= :delta: H - T :delta: S. Those were the only equations I could think of that were related to each other. However, you would end up needing n, T, and  :delta: S so I don't get how you would do this problem. Is there some other relationship or equation that I'm missing?

[Schrödinger]

I don't think  $$ \Delta /$$:E^o refers to the emf of the cell.... I think it refers to the change in the internal energy of the system

[LHM]

So does this have to do with H=U+PdV then? How do you know what PdV is?

[MrTeo]

Considering that the pressure is constant and there are 2 moles of gaseous product and only one mole of gaseous reagent you can say the volume increases (dV>0), which is enough to answer the question.

[LHM]

Oh I see, thank you very much

I have one more question though, why did they have to mention that  :delta: E ^o is measured at constant volume?