摘要:

Thermodynamic consistency within the density-wave theory of freezing is briefly discussed. The non equivalence of different routes to calculate the change in a thermodynamic quantity upon freezing is related to the approximations involved in practical calculations. In particular, a new way of calculating entropy and volume changes is proposed. It is shown that this new route avoids an unphysical feature of the entropy formula previously proposed by other authors. The freezing of hard spheres is discussed as an illustration.

ISSN:0031-9104    

DOI:10.1080/00319108708078515

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The phase comparison pulse echo method with two reflectors has been used to determine the velocity of sound in benzene and cyclohexane in the temperature range from 283–323 K and up to the freezing pressures of the liquids, the maximum pressures being 170 and 80 MPa respectively. The density, the isothermal compressibility, the isobaric thermal expansion and the specific heat at constant pressure of both liquids have been evaluated from the measured sound velocity, using a computational method similar to that of Davis and Gordon. The calculated densities for both liquids agree well with those found in the literature.

ISSN:0031-9104    

DOI:10.1080/00319108708078516

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Experimental solubilities are reported for pyrene in binary solvent mixtures containing benzene with n-hexane, cyclohexane, n-heptane, n-octane, cyclooctane and isooctane at 26°C. Results of these measurements, combined with published pyrene and biphenyl solubilities, are used to test predictive expressions derived from the Nearly Ideal Binary Solvent (NIBS) model. The most successful equation in terms of goodness of fit involved a surface fraction average of the excess Gibbs free energy relative to Raoult's law and predicted the experimental solubilities in 17 systems with an average deviation of 2.3% and a maximum deviation of 8.9%. Two expressions approximating weighting factors with molar volumes provided accurate predictions in many systems studied but failed in their ability to predict pyrene solubilities in solvent mixtures containing benzene.

ISSN:0031-9104    

DOI:10.1080/00319108708078517

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

We have performed molecular dynamics (MD) calcuations with 256 particles to simulate the pressure of liquid and fluid nitrogen in the low and the high pressure regions. The pressure in MD calculations is extremely sensitive for the form of the potential employed and therefore this quantity is best suited to test intermolecular potentials. We have studied eight different potential models including a three-body potential. Of the potential functions considered, the existing purely effective Lennard-Jones (LJ) potentials- 1-centre and 2-centres-do not suffice to give the experimental pressure for the whole pressure range. The 2-LJ-centres models derived from potential hypersurfaces calculated by “ab initio” methods produce slightly better results and led to an optimal model potential which reflects the experimental data within the statistical error of the MD. The 2-LJ centres model potential function we used for the fit cannot model the fine structure of the “ab initio” calculated hypersurface, but describes it in a balanced way when the higher energies are excluded systematically. We have achieved this by a certain weighting procedure.

ISSN:0031-9104    

DOI:10.1080/00319108708078518

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Four approximate theories of dense liquid structure are cast into directly comparable form using a force correlation function. Numerical comparisons via computer simulation data are proposed as a result.

ISSN:0031-9104    

DOI:10.1080/00319108708078519

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The departures from Joule's Law that the internal energyUis independent of volumeVare first expressed in dense liquids in terms of specific heats and the isothermal compressibility. For condensed rare gases, described by density independent pair potentials,(∂U/∂V)Tis shown to be closely related to the vacancy formation energyEv, a correction term dependent on the density dependence of the pair function being displayed explicitly. For metals with density-dependent pair potentials,(∂U/∂V)Tis shown to involve the vacancy formation volume.

ISSN:0031-9104    

DOI:10.1080/00319108708078520

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Viscosities for binary liquid mixtures of butylamine with benzene, toluene and isomeric xylenes have been measured at 303.15 K. Excess viscosity data have been obtained. The values of nEare negative over entire composition range. This may be attributed to the dissociation of self associated butylamine by the aromatic hydrocarbons. Further, the study has been extended to investigate intermolecular interactions in terms of excess free energy of mixing, strength of interaction parameter and interaction energy between the components.

ISSN:0031-9104    

DOI:10.1080/00319108708078521

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Excess volumes(VE)for the binary liquid mixtures of 1,2-dibromoethane withn-propanol, n-butanol, n-pentanol,n-hexanol,n-heptanol,n-octanol andn-decanol have been measured as a function of composition at 303.15 K by a dilatometric method.VEispositive over the entire range of composition in all the seven systems. The positive excess volumes increase with increase in chain length from (C3to C10). The results are explained in terms of the break up of hydrogen bonds, interstitial accommodation of 1.2-dibromoethane molecules in self associated alcohol and the possible hydrogen bond interaction of the type Br H-O between unlike molecules.

ISSN:0031-9104    

DOI:10.1080/00319108708078522

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

An approximate liquid structure theory due to LibofT is employed at the melting point of close-packed metals to calculate the vacancy formation energy in the hot crystal. Numerical calculations are proposed, from computer simulation experiments, to test this theory rather directly.

ISSN:0031-9104    

DOI:10.1080/00319108708078523

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The static structure factor for a dispersion of charged colloidal particles is calculated in the Random Phase Approximation. The effects of the electrostatic repulsion between the particles is split into two parts; a strong short range repulsion which is included in the reference system through an enhanced effective hard sphere diameter and a long range interaction of DLVO type that is treated as a perturbation.

ISSN:0031-9104    

DOI:10.1080/00319108708078524

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor