Vapor pressure isotope effects in liquid methyl fluoride

Oi, Takao; Shulman, Jan; Popowicz, Anthony; Ishida, Takanobu

doi:10.1021/j100239a038

Cited by 18 publications

(16 citation statements)

References 8 publications

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“…The agreement is within the lim its of the precision of the LVIFF experiments. This supports our interpretation of the temperature coeffi cient of the LVIFF data for the CD3H -CH 4 system and adds credibility to the cell model calculations for the deuteromethanes [22], An analysis of the temperature coefficients of the VPIE and LVIFF data for the CD3F -C H 3F system suggests a reinterpretation given the VPIE data [21]. A least squares fit of the VPIE data to (15) with Cx= 0 gives B{ =4.444 + 0.046 K. Attempts to reproduce the VPIE data using the cell model with a temperature dependent F matrix give Bl --6.16 K, cf.…”

Section: Discussionsupporting

confidence: 81%

“…In fact, the data are not sufficiently extensive nor accurate to warrant the introduction of different coefficients for the quadratic terms in the density expansions of <F2 (7), <0 2U) and (<vn) -vig). With this approximation (2) and (3) -In a (CD3H/CH4),/(CD3H/CH4)v; ...... least squares fits of VPIE data of [21] (methyl fluoride) and [20] (methane).…”

Section: Discussionmentioning

confidence: 99%

“…In the case of methane there is the usual red shift of the C -H vibra tions in the liquid phase compared with the vapor with the result that deuteromethanes have higher va por pressures than the protium isomer at high temper atures and show the cross over at low temperatures [20]. In the case of methyl fluoride the D/H VPIE is normal [21]. The two largest contributions to the deu terium VPIE in methyl fluoride come from a blue shift in the asymmetric C -H stretching vibration and a red shift in the F -C H 3 stretching mode.…”

Section: Introductionmentioning

confidence: 99%

“…The contributions from translation, rotation and internal vibration to the VPIEs in the liquid in equi librium with vapor at low density have been analyzed in detail for these systems [21,22], These analyzes will facilitate the interpretation of the vapor pressure iso tope effect of the liquid in equilibrium with high den sity vapors.…”

Section: Introductionmentioning

confidence: 99%

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Temperature Dependence of the Liquid-Vapor Isotopic Fractionation Factors in CD₃H-CH₄ and CD₃F-CH₃F Mixtures

Popowicz

Lub

Bigeleisenc

1991

Zeitschrift Für Naturforschung A

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zum 60. Geburtstag gewidmetThe liquid-vapor isotope fractionation factors, LVIFF, a = CD3X/CH3X)j/(CD3X/CH3X)v, of CD3H-CH4 and CD3F CH3F mixtures have been measured from 102 160 K and 182 254 K, respectively. The results are in good agreement with previous vapor pressure ratios, VPIE, which cover the ranges 90 112 K and 132 211 K, respectively. Over the temperature ranges of the LVIFF measurements, lna is negative for the CD3H-CH4 mixture and positive for the CD3F-CH3F mixture. There is significant curvature in a plot of T2 In a vs. T for the CD3H-CH4 mixture. The curvature is related to the densities of the liquid and vapor phases. It is shown that an expansion of the pair correlation function up to powers of the square of the densities of the liquid and vapor phases accounts for the T2 In a vs. T curvature and leads to In a equal to zero at the critical temperature. Correction of the LVIFF values of T2 In a for the density effect gives values for the contributions of translation, rotation and internal vibration in good agreement with previous cell model calculations. Similar treatment of the LVIFF data on the CD3F-CH3F mixture leads to the conclusion that the internal zero point energy effect on the differences in the heats of vaporization of CH3F and CD3F makes a small contribution to the overall difference in free energies of vapor ization.

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Temperature Dependence of the Liquid-Vapor Isotopic Fractionation Factors in CD₃H-CH₄ and CD₃F-CH₃F Mixtures

Popowicz

Lub

Bigeleisenc

1991

Zeitschrift Für Naturforschung A

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“…The procedure for the measurement of isotopic va por pressures in the cryostat has been described in our earlier papers [11][12][13].…”

Section: Methodsmentioning

confidence: 99%

Vapor Pressure Isotope Effects in Liquidand Solid Ammonia

King

Popowicz

et al. 1989

Zeitschrift Für Naturforschung A

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Dedicated to Professor Jacob Bigeleisen on the occasion of his 70tli birthdayThe H/D and 14N/15N vapor pressure isotope effects in liquid and solid ammonia have been measured at temperatures between 163 K and 243 K. The isotopic vapor pressure data have been fitted to T ln (P' P) = A/T-B for the liquid/liquid, liquid/solid and solid/solid ranges of temperature. The triple points are; 195.41 K (45.49 torr) for 14NH3, 198.96 K (48.35 torr) for 14ND3, and 195.58 K (48.83 torr) for 15NH3. The isotopic difference in the vapor pressures of NH3 and ND3 at temper atures between 195.41 K and 198.96 K is nearly independent of temperature within the present experimental uncertainty. The phase ratios of the reduced partition function ratios, / it,//gas and /soi//gas, deduced from these results are well represented by Tin (fc/fg) = A/T-B. Molecular forces in the liquid and solid ammonias are discussed using a simple cell and a 4-molecular unit cell model, respectively. The librational motions in the liquid are almost as highly hindered as they are in the solid, but the directionality of the external forces on nitrogen atoms in liquid ammonia is not as well defined as in the solid.

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Thermodynamics of liquid mixtures of xenon and methyl fluoride

Fonseca

Lobo

1989

Fluid Phase Equilibria

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Vapor pressure isotope effects in liquid methyl fluoride

Cited by 18 publications

References 8 publications

Temperature Dependence of the Liquid-Vapor Isotopic Fractionation Factors in CD₃H-CH₄ and CD₃F-CH₃F Mixtures

Temperature Dependence of the Liquid-Vapor Isotopic Fractionation Factors in CD₃H-CH₄ and CD₃F-CH₃F Mixtures

Vapor Pressure Isotope Effects in Liquidand Solid Ammonia

Thermodynamics of liquid mixtures of xenon and methyl fluoride

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Vapor pressure isotope effects in liquid methyl fluoride

Cited by 18 publications

References 8 publications

Temperature Dependence of the Liquid-Vapor Isotopic Fractionation Factors in CD3H-CH4 and CD3F-CH3F Mixtures

Temperature Dependence of the Liquid-Vapor Isotopic Fractionation Factors in CD3H-CH4 and CD3F-CH3F Mixtures

Vapor Pressure Isotope Effects in Liquidand Solid Ammonia

Thermodynamics of liquid mixtures of xenon and methyl fluoride

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Temperature Dependence of the Liquid-Vapor Isotopic Fractionation Factors in CD₃H-CH₄ and CD₃F-CH₃F Mixtures

Temperature Dependence of the Liquid-Vapor Isotopic Fractionation Factors in CD₃H-CH₄ and CD₃F-CH₃F Mixtures