ΔG =
ΔH – TΔS
If ΔG < 0,
the reaction is spontaneous in the forward direction.
If ΔG > 0,
the reaction is nonspontaneous in the forward direction
If ΔG = 0,
the system is at equilibrium
Standard free energy of formation (∆G°f):
the free energy change for the formation of one mole of a substance from its elements in their standard state at 1 bar and 25 °C.
ΔG° =
ΣnΔG° f (products) – ΣnΔG° f (reactants)