## Non-spontaneous

$\Delta G^{\circ}= \Delta H^{\circ} - T \Delta S^{\circ}$

$\Delta G^{\circ}= -RT\ln K$

$\Delta G^{\circ}= \sum \Delta G_{f}^{\circ}(products) - \sum \Delta G_{f}^{\circ}(reactants)$

veneziaramirez 3I
Posts: 57
Joined: Fri Sep 29, 2017 7:07 am

### Non-spontaneous

What does it mean for a reaction to be non-spontaneous yet its reverse reaction to be spontaneous? Why is its reverse reaction spontaneous?

Nora Sharp 1C
Posts: 53
Joined: Sat Jul 22, 2017 3:00 am

### Re: Non-spontaneous

If a reaction is non-spontaneous, its deltaG is positive and therefore the formation of products is not favored. This means that it's favored for the reactants to stay reactants instead of undergoing the reaction, and if there were a great number of products under certain conditions, the reaction would proceed in the reverse to make more reactants.

In order to find the deltaG of a reverse reaction, just multiply the deltaG of the original reaction by -1, so for a non-spontaneous reaction with a positive deltaG, the reverse reaction would be a spontaneous reaction with negative deltaG.

Varsha Sivaganesh 1A
Posts: 51
Joined: Thu Jul 13, 2017 3:00 am

### Re: Non-spontaneous

If a reaction is spontaneous (\Delta G is negative), that means that the forward reaction is favored. Just remember that this does not mean the reaction will happen quickly, it just means that if you leave the reaction alone, it will complete by itself.
So if the forward reaction is non-spontaneous (\Delta G is positive), this means that the forward reaction is nonspontaneous. However, if you were to reverse the reaction, you would flip the sign of \Delta G (making it negative now), and this shows that now the reverse reaction is spontaneous. Again, this means that if left alone, the reaction would go to completion.

Sabrina Fardeheb 2B
Posts: 51
Joined: Sat Jul 22, 2017 3:00 am
Been upvoted: 1 time

### Re: Non-spontaneous

To the posts above, why does it mean that the forward reactions are favored? What does it have to do with forward vs reverse reactions?

Meredith Steinberg 2E
Posts: 50
Joined: Thu Jul 13, 2017 3:00 am

### Re: Non-spontaneous

The forward reaction is favored when there doesn't need to be an outside source, such as increasing temperature, to catalyze the reaction. If the forward reaction is favored, then the reverse reaction is not favored (and vice versa).