(1) | F = C - P +2 |
where
F | number of degrees of freedom |
C | number of mixture components |
P | number of phases |
Pure substance
For Pure substance: C=1 and F = 3 - P.
It means that 3-Phase Equilibrium (solid, liquid an gas) has zero degrees of freedom : F = 0 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: F=1 and form a smooth line on Phase Equilibrium Diagram.
Binary Mixture
For Binary Mixture: C=2 and F = 4 - P.
It particularly means that 2-Phase Equilibrium of Binary Mixture has two degrees of freedom : F = 2 and covers a 2-dimensional area on Phase Equilibrium Diagram.
See also
Natural Science / Physics / Thermodynamics / Thermodynamic system / Phase / Phase Equilibrium
[ State of matter ][ Pure substance ] [ Mixture ][ Fluid Mixture ]
[ Thermodynamic equilibrium ][ Vapour Liquid Equilibrium (VLE) ]