Thermodynamics of the actinoid elements. Part 6. The preparation and heats of formation of some sodium uranates(VI)

Tso, T. C.; Brown, David; Judge, Austin Ian.; Holloway, John H.; Fuger, J.

doi:10.1039/dt9850001853

Cited by 12 publications

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“…Our second law result, À(3208.4 ± 5.5) kJ Á mol À1 , is in very good agreement with the values derived from solution calorimetry by Cordfunke et al À(3196.1 ± 3.9) kJ Á mol À1 [23,58,3], À(3194.7 ± 1.4) kJ Á mol À1 [55,3], and with the value recommended in [4] -(3203.8 ± 4) kJÁ mol À1 obtained for a high purity sample prepared by thermal decomposition in oxygen atmosphere of NaUO 2 (CH 3 COO) 3 [59]. The third law analysis yields a value that is about 30 kJ Á mol À1 too low, however.…”

Section: Discussionmentioning

confidence: 99%

Thermodynamic investigation of Na2U2O7 using Knudsen effusion mass spectrometry and high temperature X-ray diffraction

Smith

Colle

Raison

et al. 2015

The Journal of Chemical Thermodynamics

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a b s t r a c tThe vaporization behavior and decomposition mechanism of NaUO 3 were studied using Knudsen effusion mass spectrometry. The temperature dependence of the sodium partial pressure over the ternary phase field NaUO 3 -Na 2 U 2 O 7 -UO 2 was measured for the first time: logðP Na =PaÞ ¼ 10:98ðAE0:04ÞÀ 14; 999ðAE50Þ=ðT=KÞ. The enthalpy of formation of a-Na 2 U 2 O 7 was moreover derived from second law analysis of the data at D f H o m ða-Na 2 U 2 O 7 ; cr; T ¼ 298:15 KÞ = À(3208.4 ± 5.5) kJ Á mol À1 , in very good agreement with the value reported in the literature from solution calorimetry. The existence of three polymorphs for Na 2 U 2 O 7 (a, b, and c) was confirmed using high temperature X-ray diffraction. The two phase transitions occur above about T = 600 K, and around T = 1323 K, respectively. Our results were finally assessed with respect to similar vaporization studies carried out in neighboring ternary phase fields of the Na-U-O phase diagram.

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Section: Discussionmentioning

confidence: 99%

Thermodynamic investigation of Na2U2O7 using Knudsen effusion mass spectrometry and high temperature X-ray diffraction

Smith

Colle

Raison

et al. 2015

The Journal of Chemical Thermodynamics

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“…Making use of (H 2 0, sin) = -(285.85 ±0.04) kJ mol" 1 { [11] plus the relative partial molar enthalpy of water [12]}, of A f H" (C0 2 , sin) = -(413.26±0.20) kJ · mol" 1 [11], assuming that this value is the same as in H 2 0(1) at 101.325 kPa 2 , of z^(NaCl, sin) = -(406.8±0.4) kJ · mol -1 based on the enthalpy of solution of NaCl in 1 mol-dm" 3 HCl, +(4.46±0.40) kJ · mol" 1 [13] and 4#°(NaCl, cr) = -(411.26±0.11) kJ-mol"' and AjH°m (HCl, sin) = -(164.36±0.10) kJ-mol"' [14] we obtain, 4//°(Na 2 C0 3 ,cr) = -(1131.5 ±1.1) kJ · mol" 1 compared a value of -1130.68 kJ · mol" 1 selected by the NBS [15] or -1129.2 kJ · mol" 1 when using 4#°(Na + , aq) and A f H°m(COl", aq) from CO- DATA [11] and the enthalpy of solution of Na 2 C0 3 (cr) at infinite dilution from the NBS [15]. The 1.00 mol · dm" 3 HCl used in the calorimetry was a Merck certified solution.…”

Section: Methodsmentioning

confidence: 99%

Thermochemistry of Selected Lanthanide and Actinide Hydroxycarbonates and Carbonates

Merli

Fuger

1996

Radiochimica Acta

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Lanthanide and actinide carbonates and hydroxycarbonates are, together with the hydroxides, important compounds in the problematics of high level waste disposal, since such and related compounds may appear as solid phases as a result of the interaction of the waste with natural waters. Experimental results on the stability and relationships between these compounds, particularly the hydroxycarbonates, are relatively fragmentary and arise mainly from solubility measurements, and, to a lesser extent, from enthalpy of formation determinations.We report here the enthalpies of formation of a number of well characterized hydroxycarbonates of trivalent lanthanides, namely those of neodymium, samarium, dysprosium, ytterbium, and of americium, as well as that of neodymium sesquicarbonate, using solution calorimetry in acidic media. The obtained values are discussed in the light of literature data on existing solubility and enthalpy of formation of related compounds.Our results have been obtained with a newly conceived sealed calorimeter, briefly described in the paper, in which the C0 2 produced during the dissolution reaction is maintained in solution, thus eliminating the problem of the kinetically slow evolution of the C0 2 (g) from the medium and the irregularities in the associated thermal effect.

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ChemInform Abstract: Thermodynamics of the Actinoid Elements. Part 6. Preparation and Heats of Formation of Some Sodium Uranates(VI).

Tso¹,

Brown²,

Judge³

et al. 1986

Chemischer Informationsdienst

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Thermodynamics of the actinoid elements. Part 6. The preparation and heats of formation of some sodium uranates(VI)

Cited by 12 publications

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Thermodynamic investigation of Na2U2O7 using Knudsen effusion mass spectrometry and high temperature X-ray diffraction

Thermodynamic investigation of Na2U2O7 using Knudsen effusion mass spectrometry and high temperature X-ray diffraction

Thermochemistry of Selected Lanthanide and Actinide Hydroxycarbonates and Carbonates

ChemInform Abstract: Thermodynamics of the Actinoid Elements. Part 6. Preparation and Heats of Formation of Some Sodium Uranates(VI).

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