What is the use of knowing f_i2?

fi 2 multiplied by 100 gives the percentage of the total amount of i in the system, Mi tot , that resides in phase 2. fi 2 multiplied by Mi tot gives the absolute amount of i in phase 2. fi 2 Mi tot / V2 gives the equilibrium concentration of i in phase 2. 1- fi 2 gives i.e., the fraction of i that resides in phase 1. And so on.

Analogous equations can be derived for multiphase systems and for phases that are not quantified by volume but by their mass or surface area (see Chapter 3 in the script).

With these equations one can do many useful calculations (see below for examples). In order not to do all these calculations by hand it helps to have a spread sheet at hand that can do all these calculations.

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