Uranium thermochemical data

Hi. Thermochemical data. Heats of formation of several of these salts are available. They are based on calorimetric measurements of the heat of solution of the compounds, with oxidation of the uranium, in an aqueous medium, (Table IX) il 78). 

The uranium(IV) chloride prepared by this method is dark green in color. Since it is sensitive to moisture, it should be handled in a drybox. It melts at 863 K and dissolves readily in water with decomposition. The chloride is soluble in most polar organic solvents but is insoluble in hydrocarbons and diethyl ether. Physical properties and thermochemical data for this compound have been reported ... 

Rand and Kubaschewski have provided a critical assessment of all the available thermochemical data for binary compounds of uranium and a consistent set of values, including in some instances estimates, for enthalpies of formation and standard entropies, enthalpies of transformation, heat capacities, vapour pressures, and free energies of formation. 

It is reasonable to postulate that the main driving force for the reaction of (MeC5H4)3U(t-Bu) with hexafluorobenzene is thermodynamic. A weak uranium-carbon bond and a carbon-fluorine bond have to be broken. This is offset by the formation of a strong uranium-fluorine bond and either a carbon-carbon or a carbon-hydrogen bond. As illustrated in equation 8, the uranium-fluorine bond energy can be estimated to be on the order of 150 kcal/mol based on known thermochemical data for uranium fluorides (21), The carbon-fluorine bond dissociation energy for hexafluorobenzene is reported to be 154 kcal/mol (17), The... 

Structural metals such as Inconel in contact with a molten fluoride solution are not stable to F2, UF5, or UFe. it is clear, therefore, that when fission of uranium as UF4 takes place, the ultimate equilibrium must be such that four cation equivalents are furnished to satisfy the fluoride ions released. Thermochemical data, from which the stability of fission-product fluorides in complex dilute solution could be predicted, are lacking in... 

Nesmeyanov shows graphically all the results he has collected on the vapour pressures of the elements, together with his recommended values. The book also includes tables showing recommended values for the enthalpies of vaporization, the temperatures at which the elements exert pressures between 10 Torr and 1 atm, four-term equations, and vapour pressures at a number of rounded temperatures. Rand and Kubaschewski s Thermochemical Properties of Uranium Compounds contains many data, including heat capacity, solid transformations, melting temperature... 

Many experimental and theoretical studies of thermochemical and thermophysical properties of thorium, uranium, and plutonium species were undertaken by Manhattan Project investigators. Some of these reports appeared in the National Nuclear Energy Series [1]. These papers, and others in the literature through 1956, formed the basis for Table 11.11 Summary of thermodynamic data for the actinide elements of the first edition of this book. That table, completed by J. D. Axe and E. F. Westrum Jr, listed 126 species, of which the properties of 40 were estimates. A fair measure of the progress in actinide thermodynamics is the number of subsequent research papers and reviews another measure is the 731 species included in Table 17.14 of this chapter, few of which are estimates. 

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