The temperature-composition phase diagram for two immiscible liquids, benzene and water, is at constant pressure. When the pressure is changed with a slider, the saturation temperatures change. The overall benzene mole fraction can also be changed with a slider. The bar graph shows the moles of liquid water (blue), liquid benzene (orange), and vapor (red), which contains both components. The system contains one mole total. You can add heat to change the temperature and amounts in each phase. At a given pressure, all three phases co-exist at only one temperature. When heat is added at this temperature, one of the liquid phases completely evaporates before the temperature increases.