Thermodynamic study of the gaseous dilanthanum carbides, La/sub 2/C/sub 2/, La/sub 2/C/sub 3/, La/sub 2/C/sub 4/, La/sub 2/C/sub 5/, La/sub 2/C/sub 6/, and La/sub 2/C/sub 8/ by high temperature mass spectrometry
The high temperature Knudsen effusion mass spectrometric technique has been used to identify and characterize the molecules La/sub 2/C/sub 2/, La/sub 2/C/sub 3/, La/sub 2/C/sub 4/, La/sub 2/C/sub 5/, La/sub 2/C/sub 6/ and La/sub 2/C/sub 8/ in the equilibrium vapor above the La--Ir--graphite system. The enthalpies ..delta..H/sup degree//sub 0/ of the reaction 2La(g) +n C(graph.) = La/sub 2/C/sub n/ (g) (n = 2--6, 8) were evaluated using the third law method. For La/sub 2/C/sub 3/(g) and La/sub 2/C/sub 4/(g) a second law evaluation was also performed, indicating the linear symmetric structure as the most probable. The selected values for the reaction enthalpies were combined with ancillary literature data to yield the atomization energies ..delta..H/sup degree//sub a/,0, and the standard heats of formation ..delta..H/sup degree//sub f/,298.15 in kJ mol/sup -1/ of the gaseous dilanthanum carbides: La/sub 2/C/sub 2/ La/sub 2/C/sub 3/ La/sub 2/C/sub 4/ La/sub 2/C/sub 5/ La/sub 2/C/sub 6/ La/sub 2/C/sub 8/ UFRULE1 ..delta..H/sup degree//sub a/,0 1670 +- 40 2339 +- 27 3060 +- 21 3703 +- 50 4395 +- 50 5658 +- 60 ..delta..H/sup degree//sub f/,298.15 621 +- 40 658 +- 27 648 +- 21 717 +- 50 737 +- 50 898 +- 60
- Research Organization:
- Department of Chemistry, Texas AandM University, College Station, Texas 77843
- OSTI ID:
- 6886616
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 80:9; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Standard enthalpies of formation of cesium fluoroxysulfate (CsSO/sub 4/F) and cesium peroxydisulfate (Cs/sub 2/S/sub 2/O/sub 8/)
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
Related Subjects
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
CARBIDES
CARBON
CARBON COMPOUNDS
ELEMENTAL MINERALS
ELEMENTS
ENTHALPY
FORMATION HEAT
GRAPHITE
HIGH TEMPERATURE
IRIDIUM
LANTHANUM
LANTHANUM CARBIDES
LANTHANUM COMPOUNDS
MASS SPECTROSCOPY
METALS
MINERALS
NONMETALS
PHYSICAL PROPERTIES
PLATINUM METALS
RARE EARTH COMPOUNDS
RARE EARTHS
REACTION HEAT
SPECTROSCOPY
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS