Joe W. Magee, Ilmutdin Abdulagatov, Nikolai Polikhronidi, Rabiyat Batyrova
Following a critical review of related research, a method is described to evaluate the Yang-Yang critical anomaly strength function, , from experimental measurements of two-phase liquid ( ) and vapor ( ) isochoric heat capacities and liquid ( ) and vapor ( ) specific volumes. Direct measurements of internal energy ∆ increments and its temperature derivative are made possible with a highly specialized adiabatic calorimeter. The proposed method has been applied to molecular liquids (hydrocarbons, alcohols, water, carbon dioxide, etc. to accurately determine the values of the Yang-Yang anomaly strength parameter, = . The calorimeter provides two-phase (liquid and vapor) isochoric heat capacities ( ) and liquid and vapor specific volumes ( ) data at saturation near the critical point. These measurements have been used to evaluate the Yang-Yang anomaly strength function, . Near the critical point, the (T,V) variation of characterizes thermodynamic behavior in this region. For the first time, experimental determinations of have validated theoretical predictions by Cerdeiriña et al.27 that were based on the Compressible Cell Gas (CCG) model which obeys the Complete Scaling model with pressure mixing. With a valid Complete Scaling model for the physical nature and details of the temperature and the specific volume dependences of the , we may now separate the measured total two-phase heat capacity into individual contributions of chemical potential and vapor pressure and further, to illustrate their relative importance as a function of temperature.
Enthalpy and Internal Energy: Liquids, Solutions and Vapours
, Abdulagatov, I.
, Polikhronidi, N.
and Batyrova, R.
Yang-Yang Critical Anomaly, Enthalpy and Internal Energy: Liquids, Solutions and Vapours, Royal Society of Chemistry, Cambridge, -1, [online], https://doi.org/10.1039/9781788010214
(Accessed November 30, 2023)