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A Mass Spectrometric Study of the BeO-BeF 2 System at High Temperatures

Authors
  • Efimenko, J.
Type
Published Article
Journal
Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry
Publisher
National Institute of Standards and Technology
Publication Date
Jan 01, 1968
Volume
72A
Issue
1
Pages
75–80
Identifiers
DOI: 10.6028/jres.072A.007
PMID: 31824077
PMCID: PMC6640584
Source
PubMed Central
Keywords
License
Unknown

Abstract

Mass spectrometric studies were made at high temperatures of the vapors over BeF2(s) and BeO(s) individually and of their mixture. The sublimation enthalpy, ΔH 0 ° = 55.56 ± 0.43 kcal/mol , where 1 kcal equals 4184 J, was obtained for BeF2 by the use of a log I + T versus 1/ T plot. A complex molecule appeared in the BeF2-BeO system at high temperatures which, on the basis of its m/e position, corresponded to Be2OF2. For the reaction, BeO(s) + BeF2(g) = Be2OF2(g), a second law treatment of the data gave an enthalpy value, Δ H 0 ° = 41.56 ± 1.8 kcal/mol . The data, combined with free energy functions, resulted in a mean reaction enthalpy, Δ H 0 ° = 42.6 kcal/mol . The heat of formation for Be2OF2(g), Δ H 0 ° = − 288.3 kcal/mol , was computed using the reaction enthalpy based on the second law.

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