Solution thermodynamics near the liquid-liquid critical point I. First-order excess derivatives

abstract

We present a phenomenological approximation to the study of various non-universal features of liquid-liquid phase transitions in the framework of an approximate equation that relates the excess volume, the excess enthalpy, and the slope of the critical line. The mixtures under study are those containing 1-nitropropane (NP) or nitrobenzene (NB) and n-alkanes (CNH2N+2). The validity range of the above-mentioned equation is studied in detail for NP-CNH2N+2 systems. The consistency thus observed is within the experimental resolution limits, indicating that the equation can be extremely successful. The influence of effects at a molecular level on the slope of the critical line and on the critical amplitude of the isobaric thermal expansivity is analyzed from the microscopic interpretation of the excess volume and the excess enthalpy. This analysis is extended to NB-CNH2N+2 systems. The results reflect the importance of volumetric effects on critical behaviour, short-range anti-parallel ordering in NB appearing to be particularly relevant. (c) 2007 Elsevier B.V. All rights reserved.

keywords

CRITICAL REGION; COEXISTENCE CURVES; POLYMER-SOLUTIONS; PHASE-DIAGRAM; CHAIN-LENGTH; PRESSURE; EQUILIBRIA; MIXTURES; TEMPERATURE; TURBIDITY

subject category

Thermodynamics; Chemistry; Engineering

authors

Losada-Perez, P; Blesic, M; Perez-Sanchez, G; Cerdeirina, CA; Troncoso, J; Romani, L; Szydlowski, J; Rebelo, LPN

our authors

Share this project:

Related Publications

We use cookies for marketing activities and to offer you a better experience. By clicking “Accept Cookies” you agree with our cookie policy. Read about how we use cookies by clicking "Privacy and Cookie Policy".