## Delta G units

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

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

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

Bansi Amin 1D
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Joined: Fri Sep 29, 2017 7:05 am
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### Delta G units

In the equation ΔG° = -nFE° we end up with units of joules while with the equation ∆G°=-RTlnK, we end up with units of joules per mole. How is this possible, and is there a way for ΔG° = -nFE° to yield units joules/mole?

Michele 2C
Posts: 23
Joined: Fri Sep 29, 2017 7:06 am

### Re: Delta G units

The answer to this can be found on page 571 of the textbook in the green box. The more technical form of the equation is written as ∆Gr = - nrFE where the subscript r represents the "molar" form where n is plugged in as just a number, without the mole units. So, if there were 2 moles, then you would plug in 2 to the equation, not 2 moles, so that the units of ∆G come out to be joules/mole. I'm not sure exactly when to use this versus the other form, but I just know that sometimes you have to do it this way.

DamianW
Posts: 35
Joined: Fri Sep 29, 2017 7:06 am

### Re: Delta G units

-=spontaneous is also favorable right?

ran2000
Posts: 66
Joined: Fri Sep 28, 2018 12:15 am

### Re: Delta G units

G is always in terms of Joules. But the equation G=nFE is molarly dependent. Thus, the units are slightly different. But essentially, the conceptual idea is the same.