Is Gibbs energy negative?

1 Answer
Martin M.
May 28, 2017

The change in Gibbs free energy is used to define if a certain reaction takes place spontaneously. You can calculate the change in Gibbs free energy with:

#DeltaG=DeltaH-TxxDeltaS#

If you have

A negative free energy change
then you calculated the energy remainder, after the spontaneity of the process, that is free to use for other purposes.

A positive free energy change
then you calculated the minimum amount of energy needed to run the process spontaneously.

Remember:
#DeltaG<0# #color(blue)("Spontaneous")#
#DeltaG=0# #color(blue)("Reversible")#
#DeltaG>0# #color(blue)("Not spontaneous")#

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