Germanium-Iodine System,Thermodynamic Study assessment and complementary experiments

Literature thermodynamic data (enthalpies, entropies, and heat capacities) of the condensed species GeI₄(s)(I) and GeI₂(s) are revised. Entropies and heat capacities of the gaseous species GeI₄(g), GeI₂(g), and GeI(g) are calculated by the R.R.H.O. method. Published experimental investigations of the equilibria: GeI₄(l) ? GeI₄(g), GeI₄(s) ? GeI₄(g), 2 GeI₂ ? Ge(s) + GeI₄(g), GeI₄ ? GeI₂(g) + I₂(g), GeI₂(s) ? GeI₂(g) and Ge(s) + GeI₄(g) ? 2 GeI₂(g) are discussed. In addition, new measurements of the total pressure above the saturation ranges of the GeI₄(l) and for the reaction: Ge(s) + GeI₄(l) ? 2 GeI₂(g) are performed. Enthalpies of formation of GeI₄(g) and GeI(g) are deduced. Enthalpy of formation of GeI(g) is estimated from the evolution of the dissociation energy D°(Ge? X) (X = Cl, Br, I) against the Z atomic number and from the spectroscopic constants of this molecule. In conclusion a self consistent set of thermodynamic data concerning the germanium-iodine system is proposed.