Heat capacity of the liquid-liquid mixture perfluoroheptane and 2,2,4-trimethylpentane near the critical point

摘要

The heat capacity of the liquid-liquid mixture perfluoroheptane and 2,2,4-trimethylpentane (also nown as iso-octane) has been measured for the first time near its upper critical consolute point sing an adiabatic calorimeter. The theoretical expression for the heat capacity near the critical point ras applied to our combined data runs. The critical exponent a was determined to be 0.106 +-0.026, which agreed with theoretical predictions. When a was fixed at its theoretical value of .11, our value for the amplitude ratio A + / A~- = 0.59+-0.05 was consistent with experimental eterminations and theoretical predictions. However, the two-scale-factor universality ratio X, now onsistent among experiments and theories with a value between 0.019 and 0.020, was violated in lis system when using the published value for the correlation length.