Free Energy

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)