Some Reliability Data Compilations

The distribution disk with this book includes a folder entitled BNLDATA which contains the file bnlgener.xls, a spreadsheet in EXCEL format. It is a collection of failure rate data drawn from many sources. The file refem.txt contains the references to the table s data. There are 1,311 data entries many cite different estimates by different organizations for the failure rate of the same 

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A review of all the different methods used to investigate triplet absorption spectra and a compilation of all reliable data up to 1972 has recently been given by Labhart and Heinzelmann 26). Here we discuss the three main experimental methods used in triplet-triplet spectroscopy and review some of the important papers. 

There are some density data for solid salts above ambient temperature which are given in the form of thermal expansion coefficients. These have been listed when they seemed reliable. Above the melting point, density data are scarce. Most are available for alkali halides but those available for salts are taken from the critically evaluated compilation Janz, G.J., Thermodynamics and transport properties for molten salts, correlation equations for critically evaluated density, surface tension, electrical conductance, and viscosity data,./. Phys. Chem. Reference Data, 17, Suppl. 2, 1988. 

The complete data compilation for Cf is shown in Tables II and III. Note, as a final point, that from the analysis a heat capacity for the condensed phase is derived, from 298 K to the highest temperatures of measurements. These data are shown in Table II and plotted in Fig, 9. We believe this to be a highly-reliable curve, and, for these exotic materials, not likely to be measured directly for some time. 

A reasonable question is to enquire about the reliability of the results of such estimations. Table 1.4 compares estimated values from ACD/pRa (ver. 7) with the most reliable values for a variety of randomly chosen compoimds from the data compilation of the present work. It is clear from the data in Table 1.4 that sometimes the ACD/pKg package predicts a value that is very close to the best literature values. This is especially true for some smaller molecules, for example, 4-aminobenzoic acid or 5,5-diethylbarbituric acid. However, other predictions may be quite unreliable. It is of concern that some of the deviations in Table 1.4 are larger than the estimated error allowed by the package in specific cases, for example, ebifuramin, camptothecin, or citric acid. 

In the table "Entropy of Compounds," the values of the absolute entropy of compounds are given, as well as the entropy of formation of refractory compounds, calculated on the basis of the values for the entropy of elements. The data relative to some borides, marked by an asterisk, have been calculated by means of Istmen s well-known semi-empirical formula. The tables "Free Energy of Formation of Refractory Compounds" (AF according to Helmholtz) and "Heat Capacity" were compiled on the basis of the most reliable data and compared with the last reference data of E. Kubaschewski and O. Evans [928] the values of the heat capacity of refractory compounds have been converted to 20 C for convenience of the reader. 

Owing to the rapid development of the field from an experimental point of view, and the persistence of discussions on some of the aspects outlined above, a chapter on the pzc that includes a discussion of the relation between the electrochemical and the ultrahigh vacuum (UHV) situation in reference to the conditions at the pzc seems timely. This review of the literature will not be exhaustive but selective, taking into account the compilations already existing. In any case, the objective is to evaluate the existing data in order to recommend the most reliable. Finally, the data on pzc will be discussed in comparison with electron work function values. The role and significance of work functions in electrochemistry were discussed by Trasatti6 in 1976. 

In Table 13, results are compiled on evaluation of the A//f° values for some tetrazoles, published 20 years later by Lebedev and co-workers . In this study, refined values of the thermochemical parameters measured with the use of precision calorimeters were reported. The refined data proved the high reliability of the experimental findings ol Me If wan el al. (Table 13) <1951JA4725, 1957JPC26>. 

Like in the halide-cyanide compilation, the values of AG°, AH0 and zJS° presented mostly refer to the first step of the complex formation, as data for this step are generally most numerous, most reliable, and least objectionable to compare (77). In some cases, however, quantities referring to the sum of several steps have been calculated, in order to make possible a comparison with results for chelating ligands. In some other cases, data referring to later steps have been presented, either because they have been considered to be of special interest, or because they have been the only ones available for the system of complexes in question. 

It is important to distinguish between compilation and critical evaluation. The former lists the published experimental data, presenting it uncritically, while in the latter the published information is assessed in a variety of ways described in Section 3.3. There is a continuous range of possible types of review between these two extremes. All are valuable, and have their uses, but the modeller requires a set of recommended rate parameters for each reaction together with some indication of reliability of these recommendations in the form of error limits assigned to the rate parameters. Only critical evaluation can supply this. 

When equilibrium data can be found, as for example in the Gmehling compilations, they should, of course, be checked for thermodynamic consistency and viewed critically. They may not cover all possible temperature, pressure, and composition conditions, thus they should be incorporated into a model such as described above. Then they can be extrapolated with some measure of reliability. Many distillation simulators have VLE built into them. 

The data in the table have been derived from many sources, including both the primary literature and evaluated compilations. The Handbook of Data on Organic Compounds, Third Edition (Ref. 7) and the Chapman Hall/CRC Combined Chemical Dictionary (Ref. 8) were important sources. Other useful compilations of physical property data for organic compounds are listed in Refs. 9-19. Many boiling point values (and some melting point and density values) were taken from recent physical chemistry literature dealing with fluid properties. Where conflicts were found, the value deemed most reliable was chosen. 

Data were taken from a wide variety of reliable sources, including monographs, treatises, review articles, evaluated compilations and databases, and in many cases the primary literature. Some of the most useful references for the properties covered here are listed below. 

Benson [S.W. Benson, Thermochemical Kinetics Methods for the Estimation of Thermochemical Data and Rate Parameters, Second ed., John Wiley and Sons, New York, NY, (1976)] has presented ways for determining Arrhenius parameters in some detail using methods derived from the TST-thermodynamic approach. Although the speficics of this are beyond the scope of the presentation here, the methods are relatively rapid and reliable, and of considerable utility for those who may have further interest. Extensive compilations of data and examples are given for a large number of gas-phase reactions classified as to unimolecular fission, isomerization, bimolecular, metathesis, atom recombination, and so on. 

The quality control (QC) tests discussed in Sections 10.5 and 11.2.9 are integral parts of QA designed to check results. Some QC measures are prompt indicators that warn of problem occurrence at the time of analysis others are delayed indicators that require backtracking to And when a problem first arose. Control charts for radiation detector operation are an example of a prompt indicator of reliability. Records of deviations from the norm in an analysis or a measurement may also be prompt indicators if immediately considered. Periodic blank, blind, and replicate analyses, especially interlaboratory comparisons, are delayed indicators for which results may not be available for days or weeks after a problem has arisen. Review and assessment of compiled data are delayed indicators of information quality. 

This monograph Is a critical compilation of thermochemical data for the title field published since 1930. The enthalpies of formation at 298.15 K of some 3000 substances are listed, with estimates of error. Where enthalpies of vaporization are known or can be reliably estimated these are listed and In these cases the enthalpies of formation of both gaseous and condensed phases are given. Extensive Introductory material presents experimental procedures for reduction of experimental data of the type found In the book. Applications of thermochemical data are given, and there Is a section on methods of estimating enthalpies of formation of organic compounds. Also see items [29] and [116]. 

This critical compilation of pK values is a supplement to an earlier monograph by Kortum, Vogel, and Andrussow (see item [73]). This volume extends the literature coverage to the end of 1970 and summarizes data for some 4500 acids. In conjunction with the Kortum compilation, the total number of acids covered is si 5500. Each entry includes the name of the substance, its molecular formula, pK value the temperature, method of ateasure-ment, an assessment of reliability, and references to the literature. 

There are many compilations which hst such data and every laboratory has its favourite. It is important that reference data should have been validated in some way. Often, there is little to indicate the reliability of the various sources. In general, one should choose the most recent compilations and, in particular, one should be... 

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