Vapor-pressure isotope effects in liquid methylene fluoride

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:6926076

Kanungo, A

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''F/sub 2/ have been measured at temperatures between 149 and 244 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 ln(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 ln(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)
• OSTI ID: 6926076
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON ISOTOPES
ISOTOPE EFFECTS
DEUTERIUM
VAPOR PRESSURE
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
PHYSICAL PROPERTIES
STABLE ISOTOPES
THERMODYNAMIC PROPERTIES
400201* - Chemical &amp; Physicochemical Properties
400202 - Isotope Effects
Isotope Exchange
&amp; Isotope Separation