Studies of carbon-13 vapor pressure isotope effect in CHF/sub 3/

Technical Report · Sun Aug 01 04:00:00 EDT 1976

DOI:https://doi.org/10.2172/7230641· OSTI ID:7230641

Borodinsky, L.; Ishida, T.

The vapor pressure of /sup 13/CHF/sub 3/ relative to /sup 12/CHF/sub 3/ has been measured from 161 to 205/sup 0/K using a modified Bigeleisen distillation column and chromatography and mass spectroscopy of the oxidized samples. The data of each distillation run were reduced in light of a modified Cohen's theory of the kinetics of a square cascade of close-separation stages. The vapor pressure isotope effect for carbon substitution in CHF/sub 3/ in this temperature range was found to be an inverse effect. A trend of increasing inverse effect. A trend of increasing inverse effect with decreasing temperature has been observed. The relative vapor pressure may be expressed as ln P'/P = (217 +- 66)/T - (0.89 +- 0.36)/T, where P' and P are the vapor pressures of /sup 12/CHF/sub 3/ and /sup 13/CHF/sub 3/ respectively. A cell model liquid force field for trifluoromethane is derived and the F matrix elements fit to the observed vapor pressure isotope effect are tabulated. 37 tables, 32 fig. (DLC)

• Research Organization: City Univ. of New York, NY (USA)
• OSTI ID: 7230641
• Report Number(s): COO-3127-16
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
CARBON 13
CARBON ISOTOPES
DISTILLATION
EVEN-ODD NUCLEI
FLUORINATED ALIPHATIC HYDROCARBONS
FLUOROFORM
HALOGENATED ALIPHATIC HYDROCARBONS
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
NUCLEI
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PHYSICAL PROPERTIES
SEPARATION PROCESSES
STABLE ISOTOPES
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
VAPOR PRESSURE