Volume 35, Issue 1, March 2006
Index of content:
35(2006); http://dx.doi.org/10.1063/1.1928233View Description Hide Description
Viscosity is an important transport property for the optimum design of a chemical process plant and for the development of molecular theories of the liquid state. A large amount of experimental viscosity data has been produced for all types of liquids, from alternative refrigerants to molten salts and molten metals. The accuracy of these data is related to the operating conditions of the instrument and, for this purpose as well as for the calibration of relative instruments, standard reference data for viscosity are necessary over a wide range of temperatures. New experimental data on the viscosity of liquid toluene along the saturation line have been obtained recently, mostly at low temperatures. The quality of the data is such that recommended values can be proposed with uncertainties of 0.5% (95% confidence level) for and 2% for and A discussion about the uncertainties in the measurements and about the purity of the samples is made. The proposed value for the viscosity of liquid toluene at 298.15 K and 0.1 MPa is
35(2006); http://dx.doi.org/10.1063/1.1928236View Description Hide Description
A simple formulation is developed for the accurate estimation of flash points of miscible combustible solvent mixtures. It consists of an equation, which was previously validated for pure compounds. It is shown that this procedure allows accurate estimations for ideal and nonideal binary and ternary mixtures. This method does not need prerequisites such as the lower flammability limits of pure components and the use of the Le Chatelier law.
35(2006); http://dx.doi.org/10.1063/1.1928231View Description Hide Description
A semitheoretical approach for the ionization constant of water, is used to fit the available experimental data over wide ranges of density and temperature. Statistical thermodynamics is employed to formulate a number of contributions to the standard state chemical potential of the ionic hydration process. A sorption model is developed for calculating the inner-shell term, which accounts for the ion–water interactions in the immediate ion vicinity. A new analytical expression is derived using the Bragg–Williams approximation that reproduces the dependence of a mean ion solvation number on the solventchemical potential. The proposed model was found to be correct at the zero-density limit. The final formulation has a simple analytical form, includes seven adjustable parameters, and provides good fitting of the collected data, within experimental uncertainties, for a temperature range of and densities of
35(2006); http://dx.doi.org/10.1063/1.1937426View Description Hide Description
Cross section data have been compiled for electron collisions with nitrogen molecules, based on 104 references. Cross sections are collected and reviewed for: total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, dissociation,ionization, and emission of radiation. For each process, the recommended values of the cross section are presented for use. The literature has been surveyed through the end of 2003.
Additive Methods for Prediction of Thermochemical Properties. The Laidler Method Revisited. 1. Hydrocarbons35(2006); http://dx.doi.org/10.1063/1.1996609View Description Hide Description
A new parameterization of the Laidler method for estimation of atomization enthalpies and standard enthalpies of formation at 298.15 K for several families of hydrocarbons (alkanes, alkenes, alkynes, polyenes, poly-ynes, alkyl radicals, cycloalkanes, cycloalkenes, benzene derivatives, and polyaromatics) is presented. A total of 200 compounds (164 for liquid phase) are used for the calculation of the parameters. Comparison between the experimental values and those calculated using the group additive scheme led to an average difference of for the gas phase enthalpy of formation (excluding the polyaromatic compounds) and of for the liquid phase enthalpy of formation. The data base used appears to be essentially error free, but for some compounds (e.g., 2,2,4-trimethyl-pentane, with the highest deviation among all compounds except the polyaromatic ones) the experimental values might need a reevaluation. An Excel worksheet is provided to simplify the calculation of enthalpies of formation and atomization enthalpies based on the Laidler terms defined in this paper.
35(2006); http://dx.doi.org/10.1063/1.2035708View Description Hide Description
Wood is a complex and nonuniform material. Its overall solubility is a combination of the individual components’ ability to come into contact with the specified solvent (e.g., acetone) or blend. The components extracted from wood with a specified solvent represent the solubility of wood in that solvent at the condition described. Some wood compounds are soluble in water and organic solvents but the integral part of the cellular structure cannot be removed by common solvents at ambient temperature. High severities are needed for increased solubility/liquefaction due to temperature, time, and catalytic effects.
IUPAC-NIST Solubility Data Series. 81. Hydrocarbons with Water and Seawater—Revised and Updated. Part 9. Hydrocarbons with Water35(2006); http://dx.doi.org/10.1063/1.2131103View Description Hide Description
The mutual solubilities and related liquid–liquid equilibria of hydrocarbons with water are exhaustively and critically reviewed. Reports of experimental determination of solubility in 20 chemically distinct binary systems that appeared in the primary literature prior to end of 2002 are compiled. For ten systems sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction as well as the originally reported units. In addition to the standard evaluation criteria used throughout the Solubility Data Series, a new method based on the evaluation of the all experimental data for a given homologous series of aliphatic and aromatic hydrocarbons was used.
IUPAC-NIST Solubility Data Series. 81. Hydrocarbons with Water and Seawater—Revised and Updated. Part 10. and Hydrocarbons with Water35(2006); http://dx.doi.org/10.1063/1.2134730View Description Hide Description
The mutual solubilities and related liquid–liquid equilibria of and hydrocarbons with water and heavy water are exhaustively and critically reviewed. Reports of experimental determination of solubility in 24 chemically distinct binary systems that appeared in the primary literature prior to end of 2002 are compiled. For 12 systems sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction as well as the originally reported units. In addition to the standard evaluation criteria used throughout the Solubility Data Series, a new method based on the evaluation of all the experimental data for a given series of aliphatic and aromatic hydrocarbons was used.
A Reference Equation of State for the Thermodynamic Properties of Ethane for Temperatures from the Melting Line to 675 K and Pressures up to 900 MPa35(2006); http://dx.doi.org/10.1063/1.1859286View Description Hide Description
A new formulation for the thermodynamic properties of the fluid phase of ethane in the form of a fundamental equation explicit in the Helmholtz energy is presented. The functional form of the residual part was developed using state-of-the-art linear and nonlinear optimization algorithms. It contains 44 coefficients which were fitted to selected data for the thermal and caloric properties of ethane both in the single-phase region and on the liquid–vapor phase boundary. This work provides information on the available experimental data for the thermodynamic properties of ethane and presents all details of the new formulation. The new equation of state describes the surface of ethane with an uncertainty in density of less than 0.02%–0.03% (coverage factor corresponding to a level of confidence of about 95%) from the melting line up to temperatures of 520 K and pressures of 30 MPa. In the gaseous and supercritical region, high precision speed of sound data are represented generally within less than 0.015%. Other reliable data sets are represented within their experimental uncertainties. The primary data, to which the equation was fitted, cover the fluid region from the melting line to temperatures of 675 K and pressures of 900 MPa. Beyond this range the equation shows reasonable extrapolation behavior up to very high temperatures and pressures. In addition to the equation of state, independent equations for the vapor pressure, the saturated-liquid and saturated-vapor densities, and the meltingpressure are given. Tables of thermodynamic properties calculated from the new formulation are listed in the Appendix.
35(2006); http://dx.doi.org/10.1063/1.2149379View Description Hide Description
The supply of absolute electron-impact cross sections for molecular targets and radicals is extremely important for developing plasma reactors and testing different types of etching gases. Current demand for such models is high as the industry aims to replace traditional plasma processing gases with less polluting species. New theoretical electron impact cross sections at typical etchingplasma energies (sub 10 eV) are presented for the active radical species in a form suitable for plasma modeling. The available experimental and theoretical data are summarized for two potential feed gases, and This data cover recommended cross sections for electron scattering (total, excitation, momentum transfer, and elastic integral), electron impact dissociation, and dissociative electron attachment, wherever possible. Numerical values are given as tables in the paper and are also placed in the electronic archive.
35(2006); http://dx.doi.org/10.1063/1.2149380View Description Hide Description
The available experimental data for the density and viscosity of liquid aluminum and iron have been critically examined with the intention of establishing a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The proposed standard reference correlations for the density of the aluminum and iron are characterized by standard deviations of 0.65% and 0.77% at the 95% confidence level, respectively. The overall uncertainty in the absolute values of the density is estimated to be one of for aluminum and 0.8% for iron, which is worse than that of the most optimistic claims but recognizes the unexplained discrepancies between different methods. The standard reference correlations for the viscosity of aluminum and iron are characterized by standard deviations of 13.7% and 5.7% at the 95% confidence level, respectively. The uncertainty in the absolute values of the viscosity of the two metals is thought to be no larger than the scatter between measurements made with different techniques and so can be said to be in the case of aluminum and in the case of iron.
Wavelengths, Transition Probabilities, and Energy Levels for the Spectra of Rubidium (Rb I through Rb XXXVII)35(2006); http://dx.doi.org/10.1063/1.2035727View Description Hide Description
Energy levels, with designations and uncertainties, have been compiled for the spectra of the neutral atom and all positive ions of rubidium Wavelengths with classifications, intensities, and transition probabilities are also tabulated. In addition, ground states and ionization energies are listed. For most ionization stages experimental data are available; however for ionization stages where only theoretical calculations or fitted values exist, these are reported. There are a few ionization stages for which only a calculated ionization potential is available.
35(2006); http://dx.doi.org/10.1063/1.1836763View Description Hide Description
Energy levels, wavelengths, and transition probabilities of the first and second spectra of tungsten, W I and W II, have been compiled. Wavelengths of observed transitions and energy levels derived from those wavelengths have been obtained from a critical evaluation of the available literature. Measured transition probabilities for some of the observed transitions have been compiled from the published literature.