Energetically Favorable vs. Spontaneous

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Raneem Mokatrin 3F
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Energetically Favorable vs. Spontaneous

Postby Raneem Mokatrin 3F » Tue Feb 16, 2016 11:48 pm

Is there a difference between a reaction being energetically favorable and spontaneous? Is a reaction always spontaneous if the products have lower energy than the reactants or does activation energy play a determining role?

Hannah Markovic 3C
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Re: Energetically Favorable vs. Spontaneous

Postby Hannah Markovic 3C » Wed Feb 17, 2016 1:59 am

Yes, there is a difference. If the products have lower energy, delta H is negative and the reaction is energetically favorable but not necessarily spontaneous. Remember delta G = delta H - T(delta S). A negative delta H makes it likely that the reaction is spontaneous, but if delta S is negative and T times delta S is a large enough number, delta G could be positive which would mean that the reaction is not spontaneous. I'm not sure if activation energy is a part of it.

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Re: Energetically Favorable vs. Spontaneous

Postby Chem_Mod » Wed Feb 17, 2016 9:47 am

Raneem Mokatrin 3F wrote:Is there a difference between a reaction being energetically favorable and spontaneous? Is a reaction always spontaneous if the products have lower energy than the reactants or does activation energy play a determining role?

As Long as the change of gibbs free energy is negative, sucha a process/reaction will be spontaneous. However, it may happen very slowly if the activation energy is very high. Just remeber the gibbs free energy change of the reaction determine the direction of the reaction while the activation energy only determines the rate of the reaction.


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