Stable vs Unstable






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Hailey Johnson
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Stable vs Unstable

Postby Hailey Johnson » Sun Feb 11, 2018 4:02 pm

How does the stability of a compound relate to its free energy? I read this section in the book, but am still having trouble connecting the two.

Mike Vinci 2B
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Re: Stable vs Unstable

Postby Mike Vinci 2B » Sun Feb 11, 2018 4:21 pm

As we know, a negative delta g correlates with spontaneity. While it seems logical to assume the more spontaneity means more randomness and therefor less stability of the compound, however when the free energy is more spontaneous then there reactants will change into more products that are essentially even more stable then the reactants before. Hence, thee emphasis on stability and spontaneity comes from this notion.

ConnorThomas2E
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Re: Stable vs Unstable

Postby ConnorThomas2E » Sun Feb 11, 2018 4:31 pm

It helps to think about the compound in terms of its gibbs free energy of formation. If the free energy of formation of a compound is negative, this means that in the reaction for the formation of the compound, the elements (reactants) will tend to combine to form the compound (products). On the other hand, when free energy is positive, the elements are favored in the reaction, so the compound will decompose.

McKenna disc 1C
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Re: Stable vs Unstable

Postby McKenna disc 1C » Mon Feb 12, 2018 2:03 pm

Mike Vinci 2B wrote:As we know, a negative delta g correlates with spontaneity. While it seems logical to assume the more spontaneity means more randomness and therefor less stability of the compound, however when the free energy is more spontaneous then there reactants will change into more products that are essentially even more stable then the reactants before. Hence, thee emphasis on stability and spontaneity comes from this notion.


Ok, so a negative value for delta G corresponds to more spontaneity, which ultimately indicates that the reaction is more favorable/more likely to occur? Sorry, just trying to figure out what you're saying here! This topic confuses me.

Chem_Mod
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Re: Stable vs Unstable

Postby Chem_Mod » Mon Feb 12, 2018 2:20 pm

The lower the gibbs free energy of a compound (this value is ALWAYS positive as having negative energy makes no sense) the more stable the compound, the more readily the compound is formed. If the products are more stable (that is, they have a lower G) than the reactants then the reaction has a negative CHANGE IN G and the forward reaction is more favored.


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