MODEL CALCULATIONS OF THE THERMOCHEMICAL PROPERTIES OF GASEOUS METAL-HALIDES

Two semiempirical models for estimating the thermochemical properties of gaseous metal halides, the Rittner electrostatic model and the ionicity-corrected Birge-Sponer extrapolation, are reviewed, and the areas of applicability of the models are discussed. Possibilities for application of the Rittner model to metal mono-, di-, and trihalide systems are illustrated by examples from the IIA and IIIB metals, and extension to the lanthanide halide series is explored. Over-all, the Rittner model appears to have much promise as a tool for estimating thermochemical data, but proper usage demands that due consideration be given to the inherent limitations of the model. A simple ionicity correction removes much of the uncertainty associated with dissociation energies derived from the linear Birge-Sponer extrapolation, providing another useful tool for estimating thermochemical data. © 1979, The Electrochemical Society, Inc. All rights reserved.