Thermochemistry of Inorganic Solids. 7. Empirical Relations among Enthalpies of Formation of Halides

摘要

In the present paper we continue our investigation of empirical relations among the enthalpies of formation of (e of) solid inorganic salts. In earlier papers we have reported a number of simple relations which permit us to estimate the enthalpy of formation for large numbers of inorganic salts and their hydrates. In recent paper, we have presented evidence that E of any three classes of oxygen containing compounds such as oxides, hydroxides, carbonates, sulfates, and nitrates can be related quantitatively by a two-parameter linear equation. In this paper, we show that such a relationship is also valid for the solid halides. Unless otherwise stated, thermochemical data used here are taken from NBS Tables, and values are given for standard enthalpies of formation per mole of metal atom and at 298 K in kcal/mol. The existing data on E of all solid fluorides, chlorides, bromides, and iodides where the data for at least three halides are available for a particular metal M are listed in Table 1. The values listed for actinide compounds are taken from a recent IAEA publication. The difference in E of between any two halides MXn and MYn per valence state of each metal are listed in Table II. Although no obvious relationship is found between E of individual compounds, the values obtained for differences in Table II show systematic and monotonic behavior.