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In each phase chemical potential is a function of *P* and
*T*. Phase equilibrium condition:

In other words, two equations have one isolated solution!

Binary mixtures: we add a new variable--concentration *c* and have *two*
chemical potentials and . What is the largest number of
phases to coexist?

If there are *r* phases, we have *r*+2 variables (*P*, *T*, *c*^{I},
*c*^{II},...). There are 2*r* chemical potentials--2(*r*-1)
equations. They have unique solution, if *r*+2=2(*r*-1), or *r*=4. In
binary solutions four phases can coexist in a special point!

General case: *n*-component mixture, *r* phases. We have 2+*r*(*n*-1)
variables for *n*(*r*-1) equations. Maximal value for *r* is
2+*r*(*n*-1)=*n*(*r*-1), or

*r*=*n*+2

© 1997

Thu Oct 2 21:02:12 EDT 1997