Thermodynamics of mixtures of non-spherical molecules

Thermodynamic properties of liquid mixtures in which strong anisotropic intermolecular forces exist are studied using the Pade approximant method used by Stell et al. for pure fluids. Equations for the third-order perturbation term are derived for a general intermolecular potential of multipolar type. Using a mixture of Lennard-Jones molecules as the reference system, the effects of adding point dipole, quadrupole and anisotropic overlap potentials are calculated. Numerical results are presented (at low pressures) for the effect of these forces on the excess functions, and on the vapor-liquid equilibrium curves. These anisotropic forces lead to positive deviations from Raoult's law. Strong polar and quadrupolar forces may cause liquid-liquid immiscibility to occur. Numerical calculations are presented to illustrate such behaviour; these systems have upper critical solution points.

[1]  K. Gubbins,et al.  A new perturbation expansion for fluids of nonspherical molecules , 1975 .

[2]  K. Gubbins,et al.  Theory of surface tension for molecular fluids , 1975 .

[3]  I. R. Mcdonald,et al.  Perturbation theory for mixtures of polar fluids , 1975 .

[4]  K. Gubbins,et al.  Excess thermodynamic properties for liquid mixtures of non-spherical molecules , 1975 .

[5]  M. S. Ananth,et al.  Perturbation theory for equilibrium properties of molecular fluids , 1974 .

[6]  T. W. Melnyk,et al.  Thermodynamics of dipolar hard sphere mixtures , 1974 .

[7]  L. Verlet,et al.  Perturbation theories for polar fluids , 1974 .

[8]  J. Valleau,et al.  Dipolar hard spheres: A Monte Carlo study , 1974 .

[9]  K. Gubbins,et al.  Perturbation theory for molecular fluids using a nonspherical reference potential , 1974 .

[10]  I. R. Mcdonald,et al.  The radial distribution function in fluid mixtures: Conformal solution theory and molecular dynamics results , 1974 .

[11]  I. R. Mcdonald.  Application of thermodynamic perturbation theory to polar and polarizable fluids , 1974 .

[12]  G. S. Rushbrooke,et al.  Theory of polar liquids , 1973 .

[13]  K. Gubbins,et al.  Monte Carlo study of perturbation theory for the radial distribution function , 1973 .

[14]  I. R. Mcdonald.  Excess thermodynamic properties of mixtures of Lennard-Jones liquids , 1972 .

[15]  A. Bellemans.  Free energy of an assembly of nonspherical molecules with a hard core , 1968 .

[16]  L. Verlet.  Computer "Experiments" on Classical Fluids. II. Equilibrium Correlation Functions , 1968 .

[17]  M. E. Rose,et al.  Elementary Theory of Angular Momentum , 1957 .

[18]  J. Pople.  The statistical mechanics of assemblies of axially symmetric molecules - II. Second virial coefficients , 1954, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[19]  I. R. Mcdonald,et al.  Equilibrium theory of liquid mixtures , 1973 .

[20]  K. Gubbins,et al.  Perturbation theory for the angular pair correlation function in molecular fluids , 1972 .

[21]  I. R. Mcdonald,et al.  An equation of state for simple liquids , 1972 .

[22]  G. Mansoori,et al.  Statistical thermodynamics of mixtures. A new version for the theory of conformal solution , 1972 .

[23]  R. J. Bell.  Multipolar expansion for the non-additive third-order interaction energy of three atoms , 1970 .

[24]  A. Messiah.  Quantum Mechanics , 1961 .

[25]  John S. Rowlinson,et al.  Liquids and liquid mixtures , 1959 .