Enthalpies of formation of hexahalide complexes of uranium(III)

Journal Article · · Sov. Radiochem. (Engl. Transl.); (United States)

OSTI ID:6549217

Aurov, N A; Chirkst, D E

The enthalpies of solution of uranium-containing elpasolites in a solution of 4 M HCl + 0.005 M Na/sub 2/SiF/sub 6/ + 10/sup -6/ M H/sub 2/PtCl/sub 6/ were measured with a calorimeter with an isothermal casing. The standard enthalpies of formation at 298.15/sup 0/K from binary halides (and from the elements and gaseous bromine) were calculated in kJ/mole: -23.0 +/- 2.2 (-2184.4 +/- 4.0) for K/sub 2/NaUCl/sub 6/; -25.1 +/- 0.9 (-2174.7 +/- 3.4) for Rb/sub 2/NaUCl/sub 6/; -26.5 +/- 1.0 (-2199.6 +/- 3.5) for Cs/sub 2/NaUCl/sub 6/; -24.1 +/- 1.0 (-1967.1 +/- 3.6) for K/sub 2/NaUBr/sub 6/; -47.2 +/- 1.3 (-2014.2 +/- 3/7) for Cs/sub 2/NaUBr/sub 6/-Ha. On the basis of an analysis of experiments on the dissolution of uranium fluorides and tetrachloride, a new value ..delta..H/sup 0/f(UCl/sub 4/, c) = -1034.6 +/- 3.0 kJ/mole was proposed. The enthalpies of formation corresponding to this value were recalculated: -877.2 +/- 3.3 for UCl/sub 3/ (c) and -748.3 +/- 3.4 kJ/mole for UBr/sub 3/ (c) from the elements and Br/sub 2/ (g). The enthalpies of the crystal lattices and bond energies were estimated. Values of the enthalpy of formation were calculated: -852 +/- 60 for UCl/sub 6//sup 3 -/ (g) and -744 +/- 60 kJ/mole for UBr/sub 6//sup 3 -/ (g). The stabilization of hexahalide complexes of uranium(III) is discussed.

• OSTI ID: 6549217
• Journal Information: Sov. Radiochem. (Engl. Transl.); (United States), Journal Name: Sov. Radiochem. (Engl. Transl.); (United States) Vol. 25:4; ISSN SVRDA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPLEXES
ALKALI METALS
CESIUM
COMPLEXES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DATA
ELEMENTS
ENTHALPY
EXPERIMENTAL DATA
FORMATION HEAT
HALIDES
HALOGEN COMPOUNDS
INFORMATION
METALS
NUMERICAL DATA
PHYSICAL PROPERTIES
POTASSIUM
REACTION HEAT
RUBIDIUM
SODIUM
SOLUTION HEAT
THERMODYNAMIC PROPERTIES
URANIUM COMPLEXES