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Gibbs Free Energy and Stability

Posted: Sun Feb 12, 2017 1:17 am
by Niveda_Tennety_1H
For question 9.63, the answer key says that "Compounds with a positive free energy of formation are unstable with respect to the elements." Are spontaneous reaction not unstable (Gibbs free energy for spontaneous reactions is negative, right)?

Re: Gibbs Free Energy and Stability

Posted: Sun Feb 12, 2017 11:29 am
by Chem_Mod
It is all relative. If the compound has a higher free energy relative to the elements, then the formation of the compound is non spontaneous, you are putting energy into the compound, and the compound is less stable relative to the elements.

Yes, if the compound has a lower free energy relative to the elements, the reaction is spontaneous, and the compound is more stable relative to the elements. The universe tends toward disorder, and release of energy increases entropy.