Vapor pressure isotope effect in liquid methylene fluoride
The vapor pressures of the isotopic methylene fluorides /sup 12/CH/sub 2/F/sub 2/, /sup 12/CD/sub 2/F/sub 2/ and /sup 13/CH/sub 2/F/sub 2/ have been measured at temperatures between 149 and 244/sup 0/K by differential manometric techniques in a precision cryostat. Over the entire temperature range of the measurements, P(/sup 12/CH/sub 2/F/sub 2/) > P(/sup 12/CD/sub 2/F/sub 2/) and P(/sup 12/CH/sub 2/F/sub 2/) < P(/sup 13/CH/sub 2/F/sub 2/). The data are best represented by T 1n(f/sub c//f/sub g/) = (632.26 +- 97.62)/T + (19.175 +- 1.016) - (0.0532 +- 0.0025)T for the D/H effect and by T 1n(f/sub c//f/sub g/) = -(31.64 +- 1.97)/T - (0.4069 +- 0.0107) for the /sup 13/C//sup 12/C effect. A series of calculations using Wilson's FG matrix method and a modified Schachtschneider-Snyder program resulted in temperature dependent interactions between the HCF angle bending motions and the molecular rotations about the z and y axes. These interactions in the liquid give satisfactory explanation of the D/H and /sup 13/C//sup 12/C vapor pressure isotope effects, spectroscopic data, and are qualitatively consistent with the structure of CH/sub 2/F/sub 2/ clusters obtained by ab initio molecular orbital calculations.
- Research Organization:
- State Univ. of New York, Stony Brook (USA). Dept. of Chemistry
- DOE Contract Number:
- AC02-80ER10612
- OSTI ID:
- 6868593
- Report Number(s):
- DOE/ER/10612-16; ON: DE87006359
- Resource Relation:
- Other Information: Thesis. Microfiche only, copy does not permit paper copy reproduction. Thesis. Submitted by A. Kanungo
- Country of Publication:
- United States
- Language:
- English
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Vapor pressure isotope effects in liquid methylene difluoride
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON 13
ISOTOPE EFFECTS
DEUTERIUM
FLUORINATED ALIPHATIC HYDROCARBONS
TEMPERATURE DEPENDENCE
VAPOR PRESSURE
CARBON ISOTOPES
EVEN-ODD NUCLEI
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PHYSICAL PROPERTIES
STABLE ISOTOPES
THERMODYNAMIC PROPERTIES
400202* - Isotope Effects
Isotope Exchange
& Isotope Separation