Vladimir S. Yungman

IVTANTHERMO FOR WINDOWS - DATABASE ON THERMODYNAMIC PROPERTIES AND RELATED SOFTWARE

A new version of the software package IVTANTHERMO for Windows intended for thermodynamic modelling of complex chemically reacting systems is described. The package includes an extensive database on thermodynamic properties of individual substances, programs for the database handling and a program, which allows the calculation of equilibrium composition and thermodynamic properties of the system to be examined. The software is intended for scientists, chemical engineers and students.

Thermodynamic Properties of Alkali Metal Hydroxides. Part 1. Lithium and Sodium Hydroxides

The data on thermodynamic and molecular properties of the lithium and sodium hydroxides have been collected, critically reviewed, analyzed, and evaluated. Tables of thermodynamic properties (C°p,Φ°=−(G°−H°(0)/T, S°, H°−H°(0), ΔfH°, ΔfG°) of these hydroxides in the condensed and gaseous states have been calculated using the results of the analysis and some estimated values. The recommendations are compared with earlier evaluations given in the JANAF Thermochemical Tables and Thermodynamic Properties of Individual Substances. The properties considered are: the temperature and enthalpy of phase transitions and fusion, heat capacities, spectroscopic data, structures, bond energies, and enthalpies of formation at 298.15 K. The thermodynamic functions in solid, liquid, and gaseous states are calculated from T=0 to 2000 K for substances in condensed phase and up to 6000 K for gases.

Thermodynamic Properties of Alkali Metal Hydroxides. Part II. Potassium, Rubidium, and Cesium Hydroxides

The data on thermodynamic and molecular properties of the potassium, rubidium and cesium hydroxides have been collected, critically reviewed, analyzed, and evaluated. Tables of the thermodynamic properties [Cp∘, Φ°=−(G°−H°(0)/T, S°, H°−H°(0), ΔfH°, ΔfG°)] of these hydroxides in the condensed and gaseous states have been calculated using the results of the analysis and some estimated values. The recommendations are compared with earlier evaluations given in the JANAF Thermochemical Tables and Thermodynamic Properties of Individual Substances. The properties considered are: the temperature and enthalpy of phase transitions and fusion, heat capacities, spectroscopic data, structures, bond energies, and enthalpies of formation at 298.15 K. The thermodynamic functions in solid, liquid, and gaseous states are calculated from T=0 to 2000 K for substances in condensed phase and up to 6000 K for gases.

Density functional theory study of conformations, barriers to internal rotations and torsional potentials of polychlorinated biphenyls

Abstract Torsional barriers, potential energy curves, structural parameters and vibrational frequencies were calculated for 119 polychlorinated biphenyls (PCBs) at the B3LYP/6-31G(d,p) density functional theory level. From these calculations, the molecular parameters of remaining 90 PCB congeners can be estimated with reasonable accuracy. The conformations and torsional barriers of PCBs are mainly determined by the number of ortho chlorine atoms, while the meta chlorine atoms have a small influence on the torsional angles and barriers. All 209 PCBs were sorted into 18 groups depending on the number of ortho and adjacent meta substituents. In each group the internal rotation behavior of PCB congeners is very similar. For PCBs with 2–4 ortho chlorine atoms, the calculated barrier heights are 10–80 kJ/mol higher than those determined earlier by semiempirical AM1 method.

Ideal gas thermodynamic properties of biphenyl

Ideal gas thermodynamic properties for biphenyl have been calculated by statistical thermodynamics method on the basis of available experimental data and the results of recent high-level quantum mechanical calculations. More precise information about the potential barriers to internal rotation and the lowest vibrational frequencies made it possible to achieve the best agreement with calorimetric results in comparison with statistical calculations published earlier. The thermodynamic functions have been also estimated using molecular structure, vibrational frequencies, and potential barrier heights of biphenyl calculated by B3LYP/cc-pVTZ density functional method.

NIST-JANAF Thermochemical Tables. III. Diatomic Hydrogen Halide Gases

The spectroscopic and thermodynamic properties of the four diatomic hydrogen halide molecules—HX(g), where X=F, Cl, Br, and I—have been reviewed. Four revised thermochemical tables result from this critical review. The revisions involved the consideration of new spectroscopic information and the use of a direct summation over states for the generation of the thermochemical tables. Compared to previous calculations, the entropies at 298.15 K are unchanged, but the high temperature values (T>4000 K) are significantly different.

Simulation of Equilibrium States of Thermodynamic Systems Using IVTANTERMO for Windows

An algorithm is suggested for the calculation of the equilibrium composition of multicomponent heterogeneous thermodynamic systems, as well as a method and algorithm for the calculation of the pressure of saturated vapors over the condensed phase. These algorithms were used in developing the IVTANTERMO software package for Windows.