How do free energy and entropy relate?

1 Answer

A few notes about Entropy:

  1. The Universe tends towards disorder
  2. There are fewer ways to be organized compared to the infinitely many ways you can be disorganized - in chemistry the disorder is molecular randomness

The Second Law of Thermodynamics states "any spontaneous process (doesn't involve outside source of energy) increases the disorder of the universe.

Here, spontaneity is NOT how FAST a reaction occurs, it just means that its capable of occurring ON ITS OWN.

Free Energy: The amount of energy in a system that is available to do useful work.

#ΔG^o= ΔH^o-TΔS^o# where #ΔH^o# is the change in enthalpy and #TΔS^o# is the change in entropy!

So if #TΔS^o > ΔH^o# then the reaction is Entropy driven: the increase in disorder provides most of the energy!