Consider a completely miscible two-component system whoseoverall composition is X, at a temperature where liquid and gasphases coexist. The composition of the gas phase at thistemperature is Xa and the composition of the liquid phase is Xb.Prove the lever rule, which says that the proportion of liquid togas is (X -Xa)/(Xb -X). Interpret this rule graphically on a phasediagram.
