SELECTED AUXILIARY DATA

This chapter presents the chemical thermodynamic data for auxiliary compounds and complexes which are used within the NEA s TDB project. Most of these auxiliary species are used in the evaluation of the recommended nickel data in Table lll-l, Table 

and Table II1-3. It is therefore essential to always use these auxiliary data in conjunction with the selected data for nickel. The use of other auxiliary data can lead to inconsistencies and erroneous results. 

The values in the tables of this chapter are either CODATA Key Values, taken from [89COX/WAG], or were evaluated within the NEA s TDB project, as described in the corresponding chapters of the uranium review [92GRE/FUG], the technetium review [99RAR/RAN], the Update review [2003GUI/FAN], the selenium review [2005OLI/NOL] and the present review. 

All data in Table IV-1 and Table lV-2 refer to a temperature of 298.15 K, the standard state pressure of 0.1 MPa and, for aqueous species and reactions, to the infinite dilution standard state (7 = 0). 

The uncertainties listed below each reaction value in Table IV-2 are total uncertainties, and correspond mainly to the statistically defined 95% confidence interval. The uncertainties listed below each value in Table lV-1 have the following significance  

This chapter presents the chemical thermodynamic data for auxiliary compounds and complexes which are used within the NEA-TDB project. Most of these auxiliary species are used in the evaluation of the recommended zirconium data in Table lll-l, Table IIT 2, and Table 111-3. It is therefore essential to always use these auxiliary data in conjunction with the selected data for zirconium. The use of other auxiliary data can lead to Inconsistencies and erroneous results. 

Note that the values in Table IV-1 and Table IV-2 may contain more digits than those listed in either [89COX/WAG] or in Chapter VI of [92GRE/FUG], because the data in the present chapter are retrieved directly from the computerised data base and rounded to three digits after the decimal point throughout. 

Species and review where adopted logio ° Reaction (kJ-moU) (kJmol ) (JK mol ) 

Species and review where adopted logio-S ° Reaction  

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The standard entropy and Gibbs energy of formation can now be calculated with selected auxiliary data to be ... 

The enthalpies of formation of the alkali metal selenides were re-evaluated by the review from the enthalpy changes of Reactions 1 and 2 exemplified for lithium in Table A-3. The temperature of the experiments was about 288 K. The reactions combine to Reaction 3 from which the enthalpy of formation of the alkali metal selenide was calculated with selected auxiliary data at 298.15 K. A correction for the formation of some Se in Reaction 2 cannot be made due to lack of data. This also pertains to the correction of the data from the experimental temperature to 298.15 K. The results are assumed to be valid at standard conditions within the error limits and the following val-... 

Concordant results were obtained for Reaction 2 with the lithium, sodium, and potassium hydroxides. The data yield with selected auxiliary data the following estimate of the standard enthalpy of formation of the hydrogen selenide ion, Af//° (HSe , 298.15 K) = (14.3 3.2) kJ-mol. ... 

Selenium forms compounds with most elements of the Periodic Table. NEA-TDB selected data for a number of these elements are not available for use as auxiliary data in the evaluation of formation data and entropies of their selenium compounds from reaction data. It would not have been a realistic task for the selenium project to assess all non-selected auxiliary data needed according to the NEA-TDB Guidelines. Instead the information required was obtained from compilations of thermochemical data such as The NBS tables of chemical thermodynamic properties and JANAF thermochemical tables supplemented by Critical reviews of. .. published in chemical Journals. The review of the literature on selenium and its compounds has thus resulted in two thermochemical data sets. One set of data is in accord with the NEA-TDB Guidelines and compatible with the requirements for addition to the NEA-TDB Data Bank. The other set, obtained with non-TDB auxiliary data, does not fulfil the requirements of the Data Bank. These facts created a problem in the presentation of the results of the selenium project, which was solved by the... 

The standard entropy value was combined with the standard entropy of zirconium metal selected in this review (Section V.1.1), the selected auxiliary data for the standard entropy of F2(g) (Chapter IV) and the selected enthalpy of formation of (3-ZrF4 to give a selected Gibbs energy change at 298.15 K of ... 

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