High-temperature equilibrium studies of the gaseous thorium chlorides

Journal Article · Tue May 15 00:00:00 EDT 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.458335· OSTI ID:6971931

Lau, K H; Hildenbrand, D L ^[1]

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1. SRI International, Menlo Park, California 94025 (USA)

High-temperature gaseous equilibria among the species Th, ThCl, ThCl{sub 2,} and ThCl{sub 3} were studied by mass spectrometry over broad temperature ranges; both enthalpy and entropy data were derived by the second law procedure. In addition, the sublimation of ThCl{sub 4} was studied by the torsion-effusion method and the thermodynamics of the gaseous tetrachloride were evaluated. Individual bond dissociation energies in ThCl{sub 4} fall within the range 489--545 kJ mol{sup {minus}1}, and vary with ligand number in a way similar to ThF{sub 4.} Only ThCl appears to have a significant electronic entropy in the experimental temperature range. For ThCl{sub 4} the experimental entropy indicates the likelihood of a regular tetrahedral structure as with ThF{sub 4}, but unlike the uranium tetrahalides which appear to be distorted tetrahedra. In the mass spectrum of ThCl{sub 4,} the fragment ions ThCl{sup +}{sub 3}, ThCl{sup +}{sub 2}, and ThCl{sup +} show a larger and more nearly correct temperature dependence than the parent ion ThCl{sup +}{sub 4}. Results are compared with those of other thorium and uranium halides.

• OSTI ID: 6971931
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 92:10; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACTINIDE COMPOUNDS
CHLORIDES
CHLORINE COMPOUNDS
DISSOCIATION HEAT
ENTHALPY
ENTROPY
EQUILIBRIUM
EVAPORATION
FLUIDS
GASES
HALIDES
HALOGEN COMPOUNDS
HIGH TEMPERATURE
MASS SPECTROSCOPY
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
REACTION HEAT
SPECTROSCOPY
SUBLIMATION
THERMODYNAMIC PROPERTIES
THORIUM CHLORIDES
THORIUM COMPOUNDS
VAPOR PRESSURE