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# Thermodynamically stable question watch

1. Does a more negative enthalpy change always imply a substance is more thermodynamically stable?
2. I think so (look at Born-Haber cycles)
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3. (Original post by alevelphysicist)
I think so (look at Born-Haber cycles)
Thanks.
4. I would look at the Gibbs free energy equation. A negative free energy change means the substance is more thermodynamically stable, and this is a balance between both entropy and enthalpy.
5. (Original post by luckybillion)
I would look at the Gibbs free energy equation. A negative free energy change means the substance is more thermodynamically stable, and this is a balance between both entropy and enthalpy.
What about hydrogenation values? I’ve just came across hydrogenation values for theoretical and actual benzene and I am slightly confused because actual benzene has less negative value but is more stable according to textbook.
6. (Original post by Janej77)
What about hydrogenation values? I’ve just came across hydrogenation values for theoretical and actual benzene and I am slightly confused because actual benzene has less negative value but is more stable according to textbook.
I would say that in general the more negative the change is, the more stable the product is compared to the reactant (or the less stable the reactant is compared to the product)

For the specific example of the hydrogenation of benzene, it was expected that the hydrogenation value would be
-360 kJmol-1 if it was a simple double bonded structure. However, because its a delocalised structure the hydrogenation values is less negative, showing that the reactant (benzene) is more stable than it was originally thought
7. (Original post by luckybillion)
I would say that in general the more negative the change is, the more stable the product is compared to the reactant (or the less stable the reactant is compared to the product)

For the specific example of the hydrogenation of benzene, it was expected that the hydrogenation value would be
-360 kJmol-1 if it was a simple double bonded structure. However, because its a delocalised structure the hydrogenation values is less negative, showing that the reactant (benzene) is more stable than it was originally thought
Thanks for your help. I understand it now.

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