Further information 3.1 The phase rule

To explore whether/owrphases of a single substance could ever be in equilibrium (such as four of the many phases of ice), we think about the thermodynamic criterion for four phases to be in equilibrium. For equilibrium, the four molar Gibbs energies would aU have to be equal, and we could write 

The conclusion we have reached is a special case of one of the most elegant results of chemical thermodynamics. The phase rule was derived by Gibbs and states that, for a system at equilibrium, 

Here P is the number of degrees of freedom, C is the number of components, and P is the number of phases. 

---

Checklist of key concepts 128 Checklist of key equations 129 Further information 3.1 The phase rule 129... 

---