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phase rule


Definition: an expression of the relationships existing between systems in equilibrium: P + V = C + 2, where P is the number of phases, V the variance or degrees of freedom, and C the number of components; it also follows that the variance is V = C + 2 - P. For H2O at its triple point, V = 1 + 2 - 3 = 0, both temperature and pressure are fixed.

Synonym(s): Gibbs phase rule

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© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review Date: Sep 19, 2016.