Thermodynamic stability of the molecules YC/sub 2/, YC/sub 3/, YC/sub 4/, YC/sub 5/, YC/sub 6/, YC/sub 7/, and YC/sub 8/ by high temperature Knudsen effusion mass spectrometry

Journal Article · Sun May 15 04:00:00 EDT 1988 · J. Chem. Phys.; (United States)

OSTI ID:5389953

Pelino, M; Haque, R; Bencivenni, L; Gingerich, K A

The molecules YC/sub 2/, YC/sub 3/, YC/sub 4/, YC/sub 5/, YC/sub 6/, YC/sub 7/, and YC/sub 8/ have been observed in a Knudsen effusion mass spectrometric investigation of the gas phase above the Y--Ir--Au--graphite system. The enthalpies ..delta..H/sup circle-open//sub 0/ of the reactions Y(g)+n C(graph) = YC/sub n/(g)(n = 2--8) were evaluated by the third law method; the second law method was employed for the gaseous molecules with up to six carbon atoms. The selected values of the reaction enthalpies ..delta..H/sup circle-open//sub 0/ were combined with ancillary literature data to yield the atomization enthalpies ..delta..H/sup circle-open//sub a//sub ,0/ and the standard enthalpies of formation ..delta..H/sup circle-open//sub f//sub ,298.15/ in kJ mol/sup -1/ of the gaseous yttrium carbides. The values of ..delta..H/sup circle-open//sub 0/ and ..delta..H/sup circle-open//sub a//sub ,0/ (in kJ mol/sup -1/) are 197 +- 5 and 1225 +- 8 for YC/sub 2/; 377 +- 10 and 1757 +- 12 for YC/sub 3/; 361 +- 8 and 2484 +- 10 for YC/sub 4/; 499 +- 10 and 3057 +- 15 for YC/sub 5/; 536 +- 15 and 3731 +- 20 for YC/sub 6/; 684 +- 35 and 4294 +- 35 for YC/sub 7/, and 693 +- 35 and 4727 +- 35 for YC/sub 8/. The values of ..delta..H/sup circle-open//sub f//sub ,298.15/ (in kJ mol/sup -1/) are 623 +- 8, 804 +- 12, 790 +- 10, 924 +- 15, 966 +- 20, 1105 +- 35, and 1124 +- 35 for YC/sub n/ (n = 2--8), respectively.

• Research Organization: Facolta' di Ingegneria, Dipartimento di Chimica, Ing. Chimica e Materiali, 67100 L'Aquila, Italy
• OSTI ID: 5389953
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 88:10; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
CARBIDES
CARBON
CARBON COMPOUNDS
CHEMICAL REACTIONS
ELEMENTAL MINERALS
ELEMENTS
ENTHALPY
FLUIDS
FORMATION HEAT
GASES
GRAPHITE
MASS SPECTROSCOPY
METALS
MINERALS
NONMETALS
PHYSICAL PROPERTIES
REACTION HEAT
SPECTROSCOPY
STABILITY
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
VERY HIGH TEMPERATURE
YTTRIUM
YTTRIUM CARBIDES
YTTRIUM COMPOUNDS