A method for calculation of the phase distribution in multiphase equil
ibrium assuming composition independent fugacity- or activity-coeffici
ents is described. The phase distribution calculation is formulated as
a minimization problem and permits automatic and efficient handling o
f an arbitary number of pure phases. An extension to reacting mixtures
is given, the result being a minimization problem with a number of in
dependent variables equal to the sum of the number of independent reac
tions and the number of nonpure phases.