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Posted: Thu Feb 14, 2019 3:31 pm
I need help thinking through how a raise in temperature affects the stability of compounds with respect to their elements. I know you can use the Gf and Hf of the compound to solve for the -TdeltaSf term in the gibbs free energy equation, and that if T increases than the whole -TdeltaSf term increases but then I get confused with what to do with that information and how to make a claim about stability. Can someone clarify this concept?
Posted: Thu Feb 14, 2019 3:55 pm
It all depends first on whether the equation represents an exothermic or endothermic reaction.
If G is negative, it is said to be a spontaneous reaction.
Posted: Thu Feb 14, 2019 6:12 pm
If the reaction is exothermic, heat is a product and increasing the temperature would cause the reaction to shift toward the reactant side, making reactants more stable and products less stable.
If the reaction is endothermic, heat is a reactant and increasing the temperature would cause the reaction to shift toward the product side, making products more stable and the reactants less stable.
Posted: Fri Feb 15, 2019 5:18 pm
For a specific compound, if it's gibbs free energy of formation is negative, then it's relatively stable.