Thermodynamic consistency near the liquid-liquid critical point
authors Losada-Perez, P; Perez-Sanchez, G; Cerdeirina, CA; Troncoso, J; Romani, L
nationality International
journal JOURNAL OF CHEMICAL PHYSICS
author keywords critical points; liquid mixtures; organic compounds; specific heat
keywords PHASE-EQUILIBRIA; BINARY-LIQUID; COEXISTENCE-CURVE; PRESSURE; MIXTURES; BEHAVIOR; WATER; TRIETHYLAMINE; TEMPERATURE; AMPLITUDE
abstract The thermodynamic consistency of the isobaric heat capacity per unit volume at constant composition C(p,x) and the density rho near the liquid-liquid critical point is studied in detail. To this end, C(p,x)(T), rho(T), and the slope of the critical line (dT/dp)(c) for five binary mixtures composed by 1-nitropropane and an alkane were analyzed. Both C(p,x)(T) and rho(T) data were measured along various quasicritical isopleths with a view to evaluate the effect of the uncertainty in the critical composition value on the corresponding critical amplitudes. By adopting the traditionally employed strategies for data treatment, consistency within 0.01 K MPa(-1) (or 8%) is attained, thereby largely improving the majority of previous results. From temperature range shrinking fits and fits in which higher-order terms in the theoretical expressions for C(p,x)(T) and rho(T) are included, we conclude that discrepancies come mainly from inherent difficulties in determining the critical anomaly of rho accurately: specifically, to get full consistency, higher-order terms in rho(T) are needed; however, the various contributions at play cannot be separated unambiguously. As a consequence, the use of C(p,x)(T) and (dT/dp)(c) for predicting the behavior of rho(T) at near criticality appears to be the best choice at the actual experimental resolution levels. Furthermore, the reasonably good thermodynamic consistency being encountered confirms that previous arguments appealing to the inadequacy of the theoretical expression relating C(p,x) and rho for describing data in the experimentally accessible region must be fairly rejected.
publisher AMER INST PHYSICS
issn 0021-9606
year published 2009
volume 130
issue 4
digital object identifier (doi) 10.1063/1.3054351
web of science category Chemistry, Physical; Physics, Atomic, Molecular & Chemical
subject category Chemistry; Physics
unique article identifier WOS:000262965000030
  ciceco authors
  impact metrics
journal analysis (jcr 2017):
journal impact factor 2.843
5 year journal impact factor 2.743
category normalized journal impact factor percentile 60.149
dimensions (citation analysis):
altmetrics (social interaction):



 


Sponsors

1suponsers_list_ciceco.jpg