Papers by Keyword: Enthalpy of Formation

Abstract: A method has been developed for calculating the stability constants of inorganic complexes of rare-earth metals at various temperatures, based on analysis of the literature data by obtaining a linear regression equation on the form: . Using this method, the stability constants of bromide LnBr²⁺ and carbonate LnCO₃⁺ complexes of europium, terbium, and gadolinium in aqueous solutions at temperatures of 50, 75, and 100 ° C were obtained. The obtained values of the coefficients А(T₁) and В(T₁) of the linear regression equation can be used to calculate the stability constants of complexes of europium, terbium, and gadolinium with other inorganic ligands at given temperatures. Based on the temperature dependence of the stability constants of bromide and carbonate complexes, their standard entropies and enthalpies of formation were calculated. Based on the obtained values of the thermodynamic functions, an assumption was made about the outer-sphere or inner-sphere nature of the complex.

Abstract: Some properties (enthalpy of formation, glass transition temperature and rheological parameters) of hyperbranched polyglycidol derivatives containing nitrate and azide functional groups were investigated. The dependence of the found properties on the molecular weight, composition and structure of the investigated substances was determined.

Abstract: Based on Miedema’s model, the enthalpy of formation, excess free-energy and partial molar excess free-energy of Sn-Pb binary alloy solders were calculated. The model of the activity coefficient for each component in the solders was established. The diagrams of enthalpy of formation, free energy versus composition and activity versus composition and temperature as well as activity coefficients as a function of composition and/or temperature were drawn. And then the relationship between the activity coefficients of elements Sn/Pb in the solders and temperature was obtained. The approaches to reduction in the volatilization of lead at high temperature were proposed from the point of views that the lead pollution to environment results from its chemical activity in the solder alloys.