ACID-BASIC PROPERTIES AND ELECTRONEGATIVITY OF OXYGEN-CONTAINING COMPOUNDS OF URANIUM

• Main Authors: V. F. Zinchenko, V. V. Menchuk, L. V. Sadkovska
• Format: Article
• Language: English
• Published: Odessa I. I. Mechnikov National University 2020-09-01
• Series: Vìsnik Odesʹkogo Nacìonalʹnogo Unìversitetu: Hìmìâ
• Subjects: кислотно-основні властивості; оксигенвмісні сполуки; уран
• Online Access: http://heraldchem.onu.edu.ua/article/view/211722

The relationship between the acid-basic properties and the electronegativity of oxygen-containing compounds of Uranium, namely, oxides, hydroxide, uranates, uranyl salts and oxohalides is examined. It is shown that Uranium dioxide and Uranium trioxide exhibit amphoteric properties; they are very weakly expressed in UO2 (range of electronegativity – from 1.84 to 1.95 eВ1/2/О2-), while the basic and acid functions of UO3 are much more pronounced –from 1.52 to 2.27 eВ1/2/О2-, respectively. The availability of sufficiently reliable thermodynamic data on a number of salts containing a particle of UO2 (uranyl), namely, sulfate, nitrate, carbonate, acetate, oxalate, as well as their hydrates, made it possible to accurately estimate the average values of the electronegativity of UO3 in its main function. Assessment of the electronegativity of acetate and oxalate acids (2.34-2.36 eВ1/2/О2-), as well as acetic anhydride (2.63eВ1/2/О2-) gave quite adequate values characteristic of relatively strong organic acids. In a similar way, the electronegativities of UF6 and UCl6 were calculated from the thermodynamic parameters of UO2F2 and UO2Cl2, which are 2.65 and 2.40 eВ1/2/О2-, respectively, which indicates their stronger acidic properties compared to UO3. For the first time, the electronegativity of U2O5 was calculated based on the thermodynamic parameters of a mixed valence oxide of the composition U3O8; its value (2.10 эВ1/2/О2-) indicates less pronounced acidic properties compared to UO3, which is consistent with the general character of the oxides and the ionic radii of U5+ and U6+. So, electronegativity of Uranium oxides in the series UO2, U2O5, UO3 varies quite natural and in agreement with generally accepted views of inorganic chemistry.