resumo
We present experimental data of the isobaric heat capacity per unit volume Cp,xV-1 for mixtures containing nitrobenzene and an alkane (CNH2N+2, with N ranging from 6 to 15) upon approaching their liquid-liquid critical points along a path of constant composition. Values for the critical amplitude A(+) have been determined. They have been combined with the previously reported ones for the leading term of the coexistence-curve width to obtain, with the aid of well-known universal relations, the critical amplitudes of the correlation length and of the osmotic susceptibility. The trends of all these critical parameters, which exhibit anomalous behavior in the low N region, are discussed in terms of particular microscopic phenomena characterizing NB-CNH2N+2 mixtures. The work is completed with an analysis of the analog of the Yang-Yang anomaly in liquid-liquid criticality: the behavior of the partial molar heat capacities of the two liquid components is found to illustrate previously uncovered asymmetry effects. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3431547]
palavras-chave
CRITICAL REGION; COEXISTENCE CURVES; HEAT-CAPACITY; CRITICAL-POINT; BINARY-MIXTURE; TURBIDITY MEASUREMENTS; CORRELATION LENGTH; N-ALKANES; LIQUIDS; SYSTEMS
categoria
Chemistry; Physics
autores
Perez-Sanchez, G; Losada-Perez, P; Cerdeirina, CA; Thoen, J
nossos autores
Germán Pérez-Sánchez
Investigador Júnioragradecimentos
We are grateful to G. Cordoyiannis for a careful reading of the manuscript. This research was supported by the "Xunta de Galicia" under Grant No. PGIDIT-06PXIB3832828PR. Assistance to P.L.-P. and G.P.-S. by the "Ministerio de Educacion y Ciencia" under the "Programa Nacional de Formacion del Profesorado Universitario" (Grant Nos. AP-2004-2947 and AP-2005-1959, respectively) is greatly appreciated.