F = C - P +2 |
where
| number of degrees of freedom | |
| number of mixture components | |
| number of phases |
For Pure substance: and
.
It means that 3-Phase Equilibrium (solid, liquid an gas) has zero degrees of freedom : thus making a single point on Phase Equilibrium Diagram, called Triple Point and characterized by a certain Temperature and Pressure.
The 2-Phase Equilibrium has one degree of freedom: and form a smooth line on Phase Equilibrium Diagram.
For Binary Mixture: and
.
It particularly means that 2-Phase Equilibrium of Binary Mixture has two degrees of freedom : and covers a 2-dimensional area on Phase Equilibrium Diagram.
Natural Science / Physics / Thermodynamics / Thermodynamic system / Phase / Phase Equilibrium
[ State of matter ][ Pure substance ] [ Mixture ][ Fluid Mixture ]
[ Thermodynamic equilibrium ][ Vapour Liquid Equilibrium (VLE) ]
Josiah Willard Gibbs, On the Equilibrium of Heterogeneous Substances, 1876 |