Читать книгу Geochemistry - William M. White - Страница 73

For a finite change at constant temperature, the Gibbs free energy change is:

(2.125)

The free energy change of formation, , is related to the enthalpy and entropy change of reaction:

(2.126)

Like other properties of state, the Gibbs free energy is additive. Therefore:

(2.127)

In other words, we can use Hess's law to calculate the free energy change of reaction. Values for at the standard state are available in compilations.