Selected Thermodynamic Data

Among aqueous species, the most important corrections are for stabilities of the complexes U02(0H)2 and U(OH)4, which are apparently less stable than proposed by Grenthe et al. (1992) by about 2.4 and 10.6 kcal/mol, respectively. At near neutral pH s, stabilities of these complexes define the minimal respective solubilities of U(VI) and U(IV) minerals in groundwater. These errors have important implications to nuclear waste disposal, where the solubilities of U(IV) and U(VI) minerals are being used to define maximum possible uranium concentrations that might be released from a geological repository for nuclear waste (cf. McKinley and Savage 1994). 

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Table 3 Selected thermodynamic data of some diorganozinc compounds... 

In the same chapter (Chapter 5), as an introduction to the paragraphs dedicated to the various groups of metals, the values relevant to a number of elementary properties have been collected. These are atomic properties (such as metallic and ionic radii, ionization energies, electronegativities, Mendeleev number, chemical scale, Miedema parameters, etc.), crystal structure and lattice parameters data of the allotropes of the elements, and selected thermodynamic data (melting and boiling temperatures and enthalpies, etc.). All these data indeed represent reference values in the discussion of the alloying behaviour of the elements. 

Under the title "Formation of Pressure Wave , Cook (Ref 53, p 324) related the pressure rise in the front of an ait "shock wave to the point at which the initial air shock wave from unconfined charges is obliterated by the emerging gas cloud of the products of detonation. His table 13.3 (our Table 2) presents some selected thermodynamic data computed by R. Becker for air shocks relating, among other quan-... 

Table 3.1.4 Selected thermodynamic data of chemical processes relevant for electrochemical energy conversion.

In this paper we present the results of an evaluation of selected thermodynamic data of arsenic species. The results are of two types with one that consists of data that have been fitted with a weighted least-squares regression, and a second that is derived from the first least-squares determined group by standard thermodynamic relationships. The results (in Tables la, lb, and 2) and their implications for geochemistry and geochemical modelling are then discussed with known occurrences, observed mineral transformations in the environment and calculated pe-pH relationships. The objective is to provide a consistent and coherent framework of thermodynamic calculations and field relationships for mineral stabilities among arsenic species. 

TABLE 1. Selected thermodynamic data (obtained by infrared spectroscopy) for the 1 1 complexes between anihne and proton acceptors or proton donors (chloroform) in cyclohexane at 25°C124,125... 

Chapter III contains a table of selected thermodynamic data for individual compounds and complexes of selenium (Table III-l), a table of selected reaction data (Table III-2) for reactions concerning selenium species and a table containing selected thermal functions of the heat capacities of individual species of selenium (Table III-3). The selection of these data is discussed in Chapter V. 

Table 111-1 Selected thermodynamic data for selenium compounds and complexes. All ionic species listed in this table are aqueous species. Unless noted otherwise, all data refer to the reference temperature of 298.15 K and to the standard state, i.e., a pressure of 0.1 MPa and, for aqueous species, infinite dilution (/ = 0). The uncertainties listed below each value represent total uncertainties and correspond in principle to the statistically defined 95% confidence interval. Values obtained from internal calculation, cf. footnotes (a) and (b), are rounded at the third digit after the decimal point and may therefore not be exactly identical to those given in Part V. Systematically, all the values are presented with three digits after the decimal point, regardless of the significance of these digits. The data presented in this table are available on computer media from the OECD Nuclear Energy Agency.

Table IV-1 contains the selected thermodynamic data of the auxiliary species and Table IV-2 the selected thermodynamic data of chemical reactions involving auxiliary species. The reason for listing both reaction data and entropies, enthalpies and Gibbs energies of formation is, as described in Chapter 111, that uncertainties in reaction data are often smaller than the derived, Af//° and AfG°, due to uncertainty accumulation during the calculations.

The selected thermodynamic data have been used to calculate the total selenium vapour pressure above solid and liquid selenium at equilibrium. The quotient between the observed and calculated pressures as a function of the inverse temperature is shown in Figure V-2. 

The selected thermodynamic data for hydrogen selenate and selenate ions, with AfG° (HSe04,298.15 K) derived in Section V.3.4.2, would then be ... 

K) = 1.087 V. With the new selected thermodynamic data used here, this datum equals 1.101 V. 

The equilibrium Hg(g) partial pressure was reported to be log (jo//j ,/bar) = 6.226 - 5900 T The evaluation made by the review involved the matching of the concentrations of the elements mercury and selenium in the gas phase assuming a stoichiometric composition. All species in the series Se(g)-Seg(g) and Hg(g) were considered. The selected thermodynamic data for the selenium species and the CODATA [89COX/WAG] values for mercury were applied. The mole fractions of the most important selenium species are given in Table A-44. 

GAM/BUG] and [2005OLI/NOL]), and their use is recommended by this review. Zirconium forms compounds with many of the elements of the Periodic Table. The sources of auxiliary data mentioned do not eontain all data that were needed. Additional auxiliary data were obtained from the literature and, when used, the source has been indicated in Chapter VI. Recalculation of data is presented in Appendix A and, where necessary, the re-evaluation has involved new auxiliary data when needed. Care has been taken that all the selected thermodynamic data at standard conditions are internally consistent. For this purpose, special software has been developed at the NEA Data Bank that is operated in conjunction with the NEA-TDB data base system, cf. Section II.6. To maintain consistency in the application of the values selected by this review, it is essential to use these auxiliary data. 

Table IV-2 Selected thermodynamic data for reactions involving auxiliary compounds...

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