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

Abstract

The heat capacity of the liquid–liquid mixture perfluoroheptane and 2,2,4-trimethylpentane (also known as iso-octane) has been measured for the first time near its upper critical consolute point using an adiabatic calorimeter. The theoretical expression for the heat capacity near the critical point was applied to our combined data runs. The critical exponent α was determined to be 0.106±0.026, which agreed with theoretical predictions. When α was fixed at its theoretical value of 0.11, our value for the amplitude ratio A+/A−=0.59±0.05 was consistent with experimental determinations and theoretical predictions. However, the two-scale-factor universality ratio X, now consistent among experiments and theories with a value between 0.019 and 0.020, was violated in this system when using the published value for the correlation length.

Critical behaviour of binary mixture of {xC6H5CN+(1−x)CH3(CH2)7CH3}: Measurements of coexistence curves, light scattering, and heat capacity

“…It was found that the variation of 0.01 in a caused the changes of about 16%, 11%, 5%, and 1.6% in A + , A À , A + /A À , and C p0 , respectively, while the contribution of the variations of T c and E within their uncertainties to the changes of the adjusting parameters were negligible. It was reported that the theoretical predictions gave the values of A + /A À being (0.537 ± 0.019) for d = 3 expansion [1], (0.530 ± 0.003) for high-temperature series [2], (0.527 ± 0.037) for e expansion [1], and (0.55 ± 0.01) for Monte Carlo simulation [33], while the experimental values were ranged between 0.52 and 0.59 [26,28,30,32,[34][35][36][37][38][39]. The value of A + /A À determined in this study in the temperature range of ±2.8 K from the critical point is 0.533, which is in excellent agreement with the theoretical prediction of 0.530 for hightemperature series.…”

Critical behavior of binary mixture of {x C6H5CN + (1 −x) CH3(CH2)12CH3}: Measurements of coexistence curves, turbidity, and heat capacity

“…The experimental values of this ratio reported in literatures varied from 0.009 to 0.033 [37,[44][45][46][47]. Substitution of the values of A + determined from heat capacity measurements (0.01385 ± 0.00002) J Á K À1 Á cm À3 and n 0 (0.275 ± 0.006) nm determined from the turbidity measurements into equation (29) yielded a value of the two-scale-factor universality ratio being 0.021 ± 0.002.…”

Heat capacity of the liquid-liquid mixture nitrobenzene and dodecane near the critical point

“…A later measurement by Pittois et al 17 confirmed the heat capacity data and results for that system. Oby et al 11 measured the heat capacity of perfluoroheptane and 2,2,4-trimethylpentane and found X = 0.009± 0.002 when using the literature value for the correlation length amplitude. More recently, Souto-Caride et al 20 measured the heat capacity and viscosity for the alkanes hexane, heptane, and octane when mixed with nitrobenzene.…”