Liquid-liquid equilibrium in the-n-heptane-n-perfluorohexane system

The shape of the liquid-liquid coexistence curve in the C7H16-C6F14 system in the molar concentration-temperature coordinates close to the critical solution point was studied by narrow-beam gamma-raying of two-phase samples. The molar volumes of the coexisting liquid phases and critical point coordinates (critical temperature T (c) = 316.266 +/- 0.03 K and critical concentration x (c) = 39.0 +/- 0.4 mol % C6F14) were determined. The critical index beta of the coexistence curve was found to be 0.322 +/- 0.005. The diameter of the coexistence curve did not obey the classic rectilinear diameter rule..