Propriedades Termodinamicas de Sistemas Liquidos simples

Abstract

The main aim of this work is to provide experimental results useful on the development of theories of the liquid state, in particular simple liquid mixtures and associated liquids. The present study, referring to the liquid mixture carbon monoxide + methane (CO-CH_4) and to associated liquid nitric oxide (NO) is part of a project which aim is the study of the effect of pressure on the thermodynamic properties of condensed gas mixtures. In a first step, pressure - Volume - temperature (pVT) properties of liquid methane at 125.00 K and of six liquid mixtures of CO+CH_4 at 116.30, 120.00 and 125.00 K were measured, from just above the saturation vapor pressure to the freezing pre sure of methane. Results show that excess volume V"E is large and negative at low pressures, becoming less negative as pressure increases. At the highest pressures, its value is almost zero. V"E versus molar fraction (x) curves are rather asymmetric at low pressures, the effect of pressure being the reestablishment of symmetry. The results are similar to those obtained with the temperature range near the critical of one of the components. Conformable solution theory, in the Van der Waals one-fluid form, reproduces the experimental results very successfully. In a second step, an apparatus has been assembled and the pVT properties of liquid nitric oxide form 120 to 170 K at pressures up to 130 Mpa have been measured. also, the vapor pressure curve has been defined and properties such as the enthalpies of vaporization, isothermal compressibility and thermal expansion coefficients as well as configurational internal energies have calculated. New values of Pitzer's acentric factor and critical volume are reported. The results show a considerable deviation when compared with nitrogen and oxygen, which is thought to be caused by liquid nitric oxide being mainly composed of dimerized moleculesAvailable from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1200 Lisboa / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga