The spontaneity of a reaction depends both on the enthalpy change, H , and entro

Question

The spontaneity of a reaction depends both on the enthalpy change, H, and entropy change, S. Reactions that release energy produce more stable products, and the universe tends toward disorder. Thus, an exothermic reaction with a positive entropy change will always be spontaneous. Mathematically, this relationship can be represented as

G=HTS

where G is the change in Gibbs free energy and T is the Kelvin temperature. If G is negative, then the reaction is spontaneous.

***If G is positive, then the reaction is nonspontaneous as written but spontaneous in the reverse direction.If H = -50.0 kJ and S = -0.300 kJ/K , the reaction is spontaneous below a certain temperature. Calculate that temperature.

Explanation / Answer

G=HTS

the minimum DG for a spontaneous process is equal to zero.

so that

0 = (-50)-T*(-0.3)

T = 166.7 k

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