∆G vs ∆G˚

[Bella Wachter 1A]

Overall, ∆G and not ∆G˚ determines spontaneity, because it takes into account Q. However, we've often used the ∆G˚ = ∆H˚ - T∆S˚and made conclusions about which temperatures a reaction would be spontaneous at. Why is it that we can do this?

[Yu Jin Kwon 3L]

I'm pretty sure both ∆G and ∆G˚determine spontaneity (based on sign). I'm not sure if this is why you thought ∆G and not ∆G˚determined spontaneity, but if ∆G=0, then that system is at equilibrium, but this concept doesn't apply to ∆G˚. Someone please correct me if I'm wrong about both ∆G and ∆G˚determining spontaneity!

[Nathan Chu 3H]

Yes, I believe both ∆G and ∆G˚can be used to determine spontaneity. At equilibrium ∆G is always equal to 0.

[Sahiti Annadata 3D]

delta G naught tells us whether the reaction is spontaneous or not under standard conditions, while delta G tells us whether the reaction is spontaneous or not under other conditions. However, they are both used to determine spontaneity.

[Kaylee Messick 3J]

From the textbook, it says that when ∆G˚is negative, it means that K>1, which is stated instead of saying that it is spontaneous, which I believe may be what you are referring to. This is because ∆G, as you stated, would depend on the actual point in the reaction at the time of calculating the value. I'm not entirely sure, however if both can be used to determine spontaneity as it might depend on the conditions.

[Sofia Lombardo 2C]

Both ∆G and ∆Gº can tell us about spontaneity. ∆Gº does so at standard conditions, while ∆G does so at any other conditions.