## G at minimum

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

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

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

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### G at minimum

Why can there no longer be any change in a system when G (Gibbs free energy) is at a minimum?

Andres Reynoso 1J
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### Re: G at minimum

Gibbs free energy is essentially a measure of how much energy we can get from a system. So if the free energy is at a minimum, then the reaction is at equilibrium and no more change in energy can be done in the system. If anyone would like to add, please feel free.

LMendoza 2I
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### Re: G at minimum

So if Gibbs Free Energy is at a maximum or minimum, it means that the reaction is at equilibrium?

Yu Chong 2H
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### Re: G at minimum

When G is at minimum, the reaction is at equilibrium so the system shouldn't have any tendency to do work spontaneously.

Michelle Lee 2E
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### Re: G at minimum

The graph for Gibbs Free Energy that we learned in lecture was the graph with the minimum. So I'm not too sure what you mean by when it is at a maximum it's at equilibrium. But I think the graph we learned is a good explanation.
When the ball is anywhere on the graph other than the lowest point, it will roll down to the lowest point. The higher the ball is, the more available energy there is to do work. I don't think there's ever a maximum unless you want to think about how much energy a reaction can actually produce but that goes into specific reactions because no two are the same. Once the ball has reached the bottom, it won't roll anymore; the ball is essentially not able to do anything anymore and this is where there is no energy left to do work which we call equilibrium.

Kevin Tabibian 1A
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### Re: G at minimum

I like to also think about the fact that equilibrium is measured where the change in G is equal to 0. This also explains why negative G values are spontaneous, because they are approaching a lower number (where dG=0). If there is less free energy it is safe to assume that there is less potential for work.

804899546
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### Re: G at minimum

How come the system isn't necessarily at equilibrium when delta G naught is zero?