## Finding Temperature Where Reaction is Spontaneous

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

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

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

Abigail Urbina 1K
Posts: 102
Joined: Thu Jul 27, 2017 3:01 am

### Finding Temperature Where Reaction is Spontaneous

Why do we have to set delta G equal to zero when we are trying to find the temperature at which a reaction is spontaneous? I just find this a little confusing because I typically associate spontaneous reactions with negative values for delta G

Lucian1F
Posts: 87
Joined: Fri Sep 29, 2017 7:07 am
Been upvoted: 1 time

### Re: Finding Temperature Where Reaction is Spontaneous

If you find it where G=0, you can figure out exactly what the temperature needs to be greater than or less than depending on the entropy for the reaction to be spontaneous

Anna Li 2E
Posts: 21
Joined: Sat Jul 22, 2017 3:00 am

### Re: Finding Temperature Where Reaction is Spontaneous

You can also think about it like hypothetically what if we did set deltaG to a negative number? For example, you set deltaG=-1 and find the T value, you could set deltaG to an even smaller negative number, (ie -0.000001) and get a different temperature value. And so forth and so forth, always using a different deltaG value. We set deltaG=0 because while that in itself is not spontaneous, it is the threshold that helps us determine the range of T values where deltaG is negative.

You can view T as being ≥ or ≤ of a certain number rather than being exactly equal to a number.