Wprowadzenie do darmowej energii

Gibbs free energy is the energy available for a system to perform work at a constant temperature and pressure. The change in free energy, or ∆G, can be used to predict a reaction's spontaneity.

Spontaneous processes increase the entropy of the universe; however, it is difficult to measure this entropy change because it includes changes in the disorder of the system being studied and its surroundings.

Using the equation for Gibbs's free energy, spontaneity can be determined by the enthalpy and entropy change of the system alone.

If the system releases heat, the surroundings absorb the heat, which influences the randomness of the surroundings. Mathematically, the entropy of the surroundings equals the negative enthalpy change of the system divided by the temperature.

Rearranging the Gibbs equation shows the negative ratio of free energy change and temperature is equal to the entropy change of the universe.