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Spontaneous Reactions

Posted: Sat Jan 28, 2017 9:33 pm
by abram_wassily_1G
Why does a negative value for the change in Gibbs's Free Energy for a specific reaction indicate that this specific reaction is spontaneous? Thanks.

Re: Spontaneous Reactions

Posted: Sun Jan 29, 2017 1:26 pm
by Arianna_Mandelli_3C
The equation of change in Gibbs free energy is delta G=delta H-T*delta S. A negative delta G value may result from a large negative delta H, which corresponds to a large increase in the entropy of the surroundings. A negative delta G value may occur even if delta H is positive, as long as the T*delta S is positive and large enough. (The delta S refers to entropy.) In both cases, the negative G value results from an increase in entropy. So, the negative delta G indicates spontaneity because it also indicates an increase of disorder.