Thermochemical data bases

Volk, F. und Bathelt, H. ICT Thermochemical Data Base, Diskette mit... 

The method preferred in the NBA Thermochemical Data Base review is the specific ion interaction model in the form of the Bronsted-Guggenheim-Scatchard approach. 

The specific ion interaction approach is simple to use and gives a fairly good estimate of activity factors. By using size/charge correlations, it seems possible to estimate unknown ion interaction coefficients. The specific ion interaction model has therefore been adopted as a standard procedure in the NEA Thermochemical Data Base review for the extrapolation and correction of equilibrium data to the infinite dilution standard state. For more details on methods for calculating activity coefficients and the ionic medium/ ionic strength dependence of equilibrium constants, the reader is referred to Ref. 40, Chapter IX. 

Fei Y. and Saxena S. K. (1986). A thermochemical data base for phase equilibria in the system Fe-Mg-Si-O at high pressure and temperature. Phys. Chem. Minerals., 13 311-324. 

Pearson, F. J., Jr. Berner, U. 1991. Nagra Thermochemical Data Base 1. Core Data. Nagra Technical Report NTB 91-17, Nagra, Wettingen, Switzerland. 

Eventually, a polymeric substance of the form -(As GaCH2)w- may be formed. Adduct formation is thought to be responsible for the observed lower decomposition temperature of Ga(CH3)3 in the presence of AsH3 relative to Ga(CH3)3 in a carrier gas (120, 121). Furthermore, with AsH3 and D2, the primary reaction product appears to be CH4 rather than CH3D, as expected on the basis of the free-radical mechanism (equations 16a-f). However, the formation of CH4 may be due to reactions of Ga(CH3)t and CH3 with adsorbed AsH v species (122). Estimates indicate that the adduct is too unstable to play a major role in the growth chemistry (129), but this conclusion is subject to uncertainties in the thermochemical data base. 

Volk, F. and Bathelt, H. ICT Thermochemical Data Base, Disc with Handbook, Fraunhofer-lnstitut fur Chemische Technologie (ICT), Pfinztal-Berghausen, 1994, 3. Update 1997... 

In order to calculate the material transport properties as given in Figures 4 and 5 we first must calculate the chemical equilibrium making use of the available thermochemical data base. Table II shows, for example, the calculated equilibrium densities of neutral and charged species near the axis (-4000 K) of a typical coitmercial HPS arc lamp. We then use the best available interaction data for cross sections to calculate the transport properties. 

The program, called Stanjan [6] (see Appendix H), is readily handled even on the most modest computers. Like the Gordon-McBride program, it is available free from the author (see Appendix H). Both approaches use the JANAF thermochemical data base [1]. 

C. Muller, G. Scacchi and G.M. Come, A Computerized Thermochemical Data Base of Molecules and Free Radicals in the Gas Phase, in The Role of Data in Scientific Progress (Elsevier, Amsterdam, 1985) pp. 173-176. 

The Radioactive Waste Management Committee (RWMC) of the OECD Nuclear Energy Agency recognised the need for an internationally acknowledged, high-quality thermochemical data base for the application in the safety assessment of radioactive waste disposal, and undertook the development of the NEA Thermochemical Data... 

One of the objectives of the NBA Thermochemical Data Base (TDB) project is to provide an idea of the uncertainties associated with the data selected in this review. As a rule, the uncertainties define the range within which the corresponding data can be reproduced with a probability of 95% at any place and by any appropriate method. In many cases, statistical treatment is limited or impossible due to the availability of only one or few data points. A particular problem has to be solved when significant discrepancies occur between different source data. This appendix outlines the statistical procedures which were used for fundamentally different problems and explains the philosophy used in this review when statistics were inapplicable. These rules are followed consistently throughout the series of reviews within the TDB Project. Four fundamentally different cases are considered ... 

WAN] Wanner, H., The NEA Thermochemical Data Base Project,... 

Osthols, E., Wanner, H., TDB-0 The NEA Thermochemical Data Base Project, Nuclear Energy Agency Data Bank, Organisation for Economic Co-operation and Development, Report, (2000), 21 pp.. Cited on page 4. 

For meaningful model simulations, it is important that the thermochemical data base is accurate and internally consistent. The data base contained in PHREEQE is the same as the data base developed for WATEQ2 (30). This data base has been critically reviewed (31) and compared with WATEQFC (32). The values of Log K for solids included in this simulation, along with appropriate reactions from which they were determined, are listed in Table VIII. 

A recent analysis of thermochemical data based on relationships between enthalpies of formation and the unshielded core potential of a moiety X, V ( ), throws some light into the behavior of silicon-hydrogen bonds in methyls lanes. Consider first the case of carbon-hydrogen bonds. The enthalpy of Reaction 12, which is shown to be a linear function of V iZ ) can be expressed in terms of bond dissociation enthalpies. Equation 13. 

The ability to model the detailed chemistry of ignition and combustion of energetic materials requires the simultaneous treatment of the chemical kinetics behavior of large chemical reaction systems combined with convective and diffusive transport of mass, momentum, and energy. Such models require the evaluation of equations of state, thermodynamic properties, chemical rate expressions, and transport properties. The computer software used to evaluate these quantities is referred to as the Chemkin package.33-35 includes an interpreter for the chemical reactions, a thermochemical data base, a linking file, and gas-phase subroutine libraries. The interpreter reads in the list of elementary chemical reactions. The forward reaction rates are given in the form of the Arrhenius rate expression... 

MULLER C., SCACCHIG., COME G.M. (1985), A ccanputerized thermochemical data base of molecules and free radicals in the gas phase, in The role of data in scientific progress sevier). 

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