Preliminary Report on the Thermodynamic Properties of Selected Light-Element and some Related Compounds.
Abstract
Preliminary precise values of the heats of formation of gaseous ClF3, ClF5, and ONF3 were determined (mean ClF bond energy: 5.5 kcal/mol less in ClF5 than in ClF3, and 19.5 kcal/mol less in ClF3 than in ClF). The heat capacity and entropy of Li3AlF6(c) were accurately measured (15-380K). Described extensively are the recently developed techniques for measuring in less than one second the heat capacity, electrical resistivity, and hemispherical total and normal spectral emittances of electrical conductors (1900K to their melting points); complete measurements on molybdenum; comparisons with previous published values; and detailed error analyses. Procedures for correcting chemical thermodynamic properties to the basis of the (new) International Practical Temperature Scale of 1968 are summarized. By infrared spectroscopy using molecular beams and matrix-isolation, all the fundamentals of 6LiCN, 7LiCN, 6LiNC, and 7LiNC were obtained except the bending frequencies of the last two molecules. It was concluded that CCl3, CBr3, and CH3 had not been proved by previous workers to have pyramidal symmetry, but probably have planar shapes. The thermochemistry of gaseous and aqueous HF is reviewed (including spectroscopic and photodissociation sources). Included are two critical reviews of the published thermodynamic data for barium and some of its compounds. The first review updates an earlier survey of low-temperature heat capacities and entropies. In the second review, selected values of the standard heats, free energies, and entropies of formation of a number of barium compounds are discussed and tabulated. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1969
- Accession Number
- AD0864380
Entities
People
- Charles W. Becket
- Thomas B. Douglas
Organizations
- National Institute of Standards and Technology