Study On Heat Capacity And Complete Scaling Of Binary Fluid Mitures

The isobaric heat capacities per unit volumes for the critical binary fluids of benzonitrile+alkanes (decane, tridecane, pentadecane and heptadecane), dimethyl carbonate+alkanes (tridecane and pentadecane), nitrobenzene+alkanes (hexane, heptane, octane, decane, tridecane and tetradecane),[C4mim][BF4]+1,4-butanediol have been measured in the wider temperature ranges of both near and far away from their upper critical consolute points by means of differential scanning calorimeter. Analyzing the measured experimental data far away from the critical temperature, the true background heat capacity Bbg and the coefficient of the background term arising from the regular part of the heat capacity E were obtained. The critical exponents, the critical amplitudes and the heat capacity background Bcr contributed by the critical fluctuation were also obtained. The values of A0+/A0-(the ratio of the critical amplitudes of the heat capacities in one and two phase regions) and a were found to be universal for different binary fluids and in agreement with the theoretical ones. Furthermore, the experimental data of the heat capacity were used to study the asymmetry of the coexistence curves for those binary systems in terms of the complete scaling theory proposed by G. Perez-Sanchez under the conditions of incomplete limit and neglecting the excess volume. The results validated the relationship between the asymmetry of the coexistence curve and the solute/solvent reduced molar volume ratio described by the complete scaling theory and indicated that the heat capacity makes important contribution to the asymmetry behavior of the coexistence curve.