**Ternary Phase Diagram with Alternate Phase Envelope**

Download the CDF file to view the simulation using the free Wolfram CDF player. |

This Demonstration shows a ternary phase diagram, including a phase envelope. This diagram is used to represent the phase behavior of mixtures of three components that are only partially miscible over a range of compositions so that phase separation occurs. In the "view diagram" option, the black point, which can be moved to any location within the triangle by clicking on that location, represents the overall composition of the mixture. Each corner of the triangle corresponds to a pure component. The mass fraction of a component in the mixture is read off the axis that is the same color as that component. These axes are labeled by drawing a line through the point; this line is parallel to the base of the triangle that is opposite the corner corresponding to that pure component.

When the black point is in the two-phase region, a tie line (large-dash black line) is shown, and the endpoints of the tie line correspond to the compositions of the two phases (α, β) that are in equilibrium. These compositions are shown when "show α phase" and "show β phase" are selected. Gray tie lines are shown when "show tie lines" is selected, and grid lines are shown when "show grid lines" is selected. The points along the left of the phase envelope boundary belong to the α phase, and the points along the right belong to the β phase. In the "view phases" option, the one- and two-phase regions are labeled. Ternary phase diagrams can also be drawn in terms of mole fractions instead of mass fractions.