1. GIBBS FREE ENERGY EQUATION

2. Spontaneous or Not?
We’ve seen the favorable conditions for a spontaneous reaction in terms of enthalpy and entropy individually
We’ve seen situations where only one of the two conditions is favorable, so how can we predict?

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4. TEMPERATURE: THE DECIDING FACTOR!
Gibbs Free Energy Equation allows us to relate the two factors at a given temperature to determine if a reaction is spontaneous
Gibbs helps us evaluate those circumstances
If Gibbs is – the reaction will occur
If Gibbs is + it will not
ΔG = ΔH – TΔS

5. Situations: Consider this
+ enthalpy and + entropy
ΔG = ΔH – TΔS

6. Situations: Consider this
- enthalpy and - entropy

8. Sample Problems
The ΔH for a certain reaction is kJ and the ΔS is kJ/ºK
Calculate the ΔG at 25º C.
Will this reaction be spontaneous at 500K?