Sublimation studies of NpO sub 2 F sub 2

Journal Article · Sat Aug 15 04:00:00 EDT 1992 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.463080· OSTI ID:7200669

Kleinschmidt, P D ^[1]; Lau, K H; Hildenbrand, D L ^[2]

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1. Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2. SRI International, Menlo Park, California 94025 (United States)

Using Knudsen effusion mass spectrometry, we have identified the following reaction as the sublimation decomposition mechanism of NpO{sub 2}F{sub 2}({ital s}): 2NpO{sub 2}F{sub 2}({ital s})=NpO{sub 2}({ital s})+O{sub 2}({ital g})+NpF{sub 4}({ital g}). From second-law analysis of the measured pressures of NpF{sub 4}({ital g}) over the temperature range 820--985 K the derived enthalpy change at 298 K is 556.8{plus minus}12.2 kJ/mol and the entropy change is 342.4 {plus minus}13.8 J/K mol. From these values and enthalpies of formation and entropies reported in the literature for the other species we calculate the enthalpy of formation of NpO{sub 2}F{sub 2}({ital s}) to be {minus}1608{plus minus}10 kJ/mol and the entropy to be 147{plus minus}9 J/K mol.

• OSTI ID: 7200669
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 97:4; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
400800 -- Combustion
Pyrolysis
& High-Temperature Chemistry
ACTINIDE COMPOUNDS
CHEMICAL REACTIONS
DECOMPOSITION
ENTHALPY
EVAPORATION
FLUID FLOW
FLUORINE COMPOUNDS
GAS FLOW
HALOGEN COMPOUNDS
KNUDSEN FLOW
MASS SPECTROSCOPY
NEPTUNIUM COMPOUNDS
OXYFLUORIDES
OXYGEN COMPOUNDS
OXYHALIDES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SPECTROSCOPY
STABILITY
SUBLIMATION
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
THERMODYNAMIC PROPERTIES
THERMODYNAMICS
TRANSURANIUM COMPOUNDS