Outline the phase diagram. Describe the phase changes that occur when perfluorohexane is added to a fixed amount of hexane at (a) 23°C, (b) 22°C. Perfluorohexane and hexane show the partial miscibility below 22.70°C. The critical concentration at the upper critical temperature is x =0.355, where the x is the mole fraction of C6F14 At22.0°C the two solutions in equilibrium have x = 0.24 and x = 0.48, respectively, and at 21.5°C the mole fractions are 0.22 and 0.51.