## Negative Delta G

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

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

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

Helen Mejia 1I
Posts: 67
Joined: Fri Sep 28, 2018 12:24 am

### Negative Delta G

What are some conditions that allow delta G to be negative?

jessicahe4Elavelle
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Joined: Fri Sep 28, 2018 12:27 am
Been upvoted: 1 time

### Re: Negative Delta G

the formula for is delta G = delta H - T delta S. So if:
- delta H is positive and delta S is negative, delta G will definitely be positive
- delta H is negative and delta S is positive, delta G will definitely be negative

RachelCheung1A
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Joined: Fri Sep 28, 2018 12:19 am

### Re: Negative Delta G

When delta H is negative and delta S is positive, it will definitely be negative delta G.
A large negative delta H and a small negative delta at a low temperature can possibly result in a negative delta G

Carine Tamamian 2B
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Joined: Fri Sep 28, 2018 12:23 am

### Re: Negative Delta G

This graph will help better visualize the concept!
Attachments

Sophie Roberts 1E
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Joined: Fri Sep 28, 2018 12:17 am

### Re: Negative Delta G

Also it is important to remember when Delta G is negative the reaction is spontaneous!
When it is positive it is non spontaneous.

Posts: 35
Joined: Fri Sep 28, 2018 12:19 am

### Re: Negative Delta G

Reactions with a negative delta G are very spontaneous, and therefore highly favorable! The more favorable a reaction is, the more it will proceed towards the products. That means that K is rather large at equilibrium because the ratio of products is high compared to reactants.

Milena Aragon 2B
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Joined: Fri Sep 28, 2018 12:19 am

### Re: Negative Delta G

The only circumstance in which delta G cannot be negative(for the forward rxn) regardless of temp. is if delta H is positive and delta S is negative.

Danielle_Gallandt3I
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Joined: Fri Sep 28, 2018 12:24 am

### Re: Negative Delta G

It is important to remember that for the majority of problems you will actually have to use the delta G equation to determine the spontaneity of the reaction, because if if delta H is positive, the combination of the (negative) entropy and the temp must be large enough to overcome the enthalpy value. This means that at different temperatures delta G can change, which makes it important to calculate delta G for every scenario.