Phase Rule At Constant Pressure
Condensed systems have no gas phase. When their properties are insensitive to the (small) changes in pressure which occur, one fewer variable needs to be specified, which results in the phase rule at constant pressure
- F = C − P + 1 ,
This is sometimes misleadingly called the "condensed phase rule", but it is not applicable to condensed systems which are subject to high pressures (for example in geology), since the effects of these pressures can be important. The rule is useful for some applications in materials science.
Read more about this topic: Gibbs' Phase Rule
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