Example 08.01 Solubility of Anthracene and Phenanthrene in Benzene

problem:

Calculate the solubility of anthracene (1) and phenanthrene (2) in benzene at q=20°C. For the calculation it should be assumed that the binary systems show ideal mixture behavior (g_i=1).

general

constants

and

definitions:

input data

Solution

First calculate the logarithm of the activity of the pure solid component at 20°C:

In an ideal liquid mixture, the activity in the liquid phase is equal to the mole fraction (solubility).

Both components are chemically very similar but show a large difference in solubility. This is mainly due to the significant difference in melting temperature and to a smaller extent because of the different heats of fusion.