3 component (ternary) system in equilibrium If the components of a system were Cl2, Br2, and I2, how could I describe this system under equilibrium conditions when the number of phases is at a maximum?

If there are 3 components, using the formula, F=M+2-P and solving for P under equilibrium conditions there would be a total of 5 phases.

Since these above components are all gases, and we know there are 5 phases, can I assume that 3 of the 5 phases will be Cl2 (gas), Br2 (gas), and I2 (gas).

For the other two phases, can I assume they consist of liquid iodine as it's commonly in the liquid phase, and cl2 (solid) as it's commonly in the liquid phase.

I'm not sure if this is correct.
If there are 3 components, using the formula, F=M+2-P and solving for P under equilibrium conditions there would be a total of 5 phases.


I understand from that you set $F=0$. Equilibrium does not necessarily mean that you have no degrees of freedom. In this case, you actually have two degrees of freedom: the molar fractions of two components, for example $X(\rm{Cl}_2)$ and $X(\rm{I}_2)$.

$X(\rm{F}_2) = 1 - X(\rm{Cl}_2) -X(\rm{I}_2)$ and cannot vary independently, so it is not a degree of freedom. Once you consider $F=2$, you only need three phases.

What about liquids and solid? Let's say that you vary temperature, and you reach the melting/condensation/etc curve in $T$ space. On the curve itself you will have four phases, three gases and (for instance) liquid chlorine. This causes you to lose a degree of freedom, which in this case is temperature. These four phases can exist only in that specific temperature.

EDIT

Following the comments on the original question, I would like to note that I was addressing a simplified case where the only phases possible are the ones listed in the original question. Once you have intermediate compounds (ICl for example) it's a whole different story.