Introduce that Gibbs free energy is a function associated with the system only and does not require assessment of the surroundings. Define free energy in terms of enthalpy, kelvin temp. and entropy. Using the formulas to determine the entropy changes for the universe, elicit the formula which can be used to determine if reaction is spontaneous or not. This formula delta G = delta H0- Tdelta S, can be used to more easily determine spontaneous reactions.