Jack L. Settle

Fluorine bomb calorimetry. Part 14.—Enthalpies of formation of the hexafluorides of sulphur, selenium, and tellurium and their thermodynamic properties to 1500°K

The energies of formation of the hexafluorides of sulphur, selenium, and tellurium were measured by direct combination of the elements in a bomb calorimeter. From these measurements the standard enthalpies of formation ΔH°f298·15(g), were calculated (in kcal mole–1) : SF6, –291.77±0.24; SeF6, –266.95±0.14; TeF6, –327.20±0.56. These values are substantially more negative then those reported by Yost and Claussen in 1933. The thermodynamic properties of these compounds have been computed and tabulated from 0 to 1500°K.

Distribution of plutonium, americium, and several rare earth fission product elements between liquid cadmium and LiClKCl eutectic

Abstract Separation factors were measured that describe the partition between molten cadmium and molten LiClKCl eutectic of plutonium, americium, praseodymium, neodymium, cerium, lanthanum, gadolinium, dysprosium, and yttrium. The temperature range was 753–788 K, and the range of concentrations was that allowed by the sensitivity of the chemical analysis methods. Mean separation factors were derived for Am-Pu, Nd-Am, Nd-Pu, Nd-Pr, Gd-La, Dy-La, La-Ce, La-Nd, Y-La, and Y-Nd. Where previously published data were available, agreement was good. For convenience, the following series of separation factors relative to plutonium was derived by combining the measured separation factors: Pu, 1.00 (basis); Am, 1.54; Pr, 22.9; Nd, 23.4; Ce, 26; La, 70; Gd, 77; Dy, 270; Y, 3000. These data are used in calculating the distribution of the actinide and rare earth elements in the pyrochemical reprocessing of spent fuel from the Integral Fast Reactor.

Partition of lanthanum and neodymium metals and chloride salts between molten cadmium and molten LiCl-KCl eutectic

Abstract The distribution of lanthanum and neodymium between a molten cadmium pool and molten LiCl-KCl eutectic was measured over the temperature range 753–788 K. Lanthanum and neodymium metals in amounts more than sufficient to form a saturated solution were added to cadmium, then progressively oxidized to salt-soluble trichlorides by additions of cadmium chloride. In the early stages of oxidation a solid metal phase existed; it can be described as a solid solution of LaCd 11 and NdCd 11 . A regular solution solubility parameter of −1990±390 (±2 σ ) was derived for the solid solution. In the later stages of oxidation only an unsaturated solution of lanthanum and neodymium in cadmium existed. Lanthanum was slightly more easily oxidized than neodymium; a separation factor of 2.5±1.1 was measured.

The enthalpy of formation of dicesium monoxide (Cs2O)

Abstract A sample of high-purity Cs2O(c) was especially prepared for a solution-calorimetric study of its enthalpy of reaction with excess water to form CsOH(aq). The standard enthalpy of formation, ΔHfo(Cs2O, c, 298.15 K), was derived to be −(82.69 ± 0.28) kcalth mol−1.

Fluorine bomb calorimetry

Techniques which were developed for fluorine bomb calorimetry are described. Construction materials, safety measures, manipulation of samples, and calorimeter calibration are discussed. Tests carried out on 25 metals and metalloids and on 15 inorganic compounds indicated that reactions of 75% of these substances with fluorine could be studied calorimetrically. It is concluded that fluorine calorimetry can be carried out without undue hazard and is

The enthalpies of formation of iodine pentafluoride and iodine heptafluoride

Abstract The energy of combustion of iodine in fluorine was measured in a bomb calorimeter and the standard enthalpy of formation of liquid iodine pentafluoride, ΔHfo(IF5, 1, 298·15 K), was calculated to be −(210·81 ± 0·39) kcal/mole. The combustion products contained variable quantities of gaseous iodine heptafluoride (IF7) in addition to IF5. A linear least squares analysis of the standard energy of combustion of iodine as a function of the ratio of IF7 to IF5 enabled a value of −(229·80 ± 0·54) kcal/mole to be deduced for ΔHfo(IF7, g, 298·15 K).

Thermochemistry of inorganic sulfur compounds III. The standard molar enthalpy of formation at 298.15 K of US1.992 (β-uranium disulfide) by fluorine bomb calorimetry☆☆☆

Abstract A thoroughly analyzed specimen of β-uranium disulfide of composition US 1.992±0.002 has been studied by fluorine-bomb calorimetry. The standard molar energy of combustion: Δ c U m o (US 1.992 , cr, β, 298.15 K) = −(4092.5±7.5) kJ·mol −1 has been determined on the basis of the reaction: US 1.992 (cr, β) + 8.976F 2 (g) = UF 6 (cr) + 1.992F 6 (g). The standard molar enthalpy of formation: Δ f H m o (US 1.992 , cr, β, 298.15 K) = −(519.7±8.0) kJ·mol −1 was derived, and from that result Δ f H m o (US 2 , cr, 298.15 K) = −(521±8) kJ·mol −1 is estimated.