Vapour pressure of isotopic liquids

Boato, G.; Casanova, G.; Scoles, G.; Vallauri, Manuela

doi:10.1007/bf02781701

Cited by 31 publications

(18 citation statements)

References 4 publications

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“…Nevertheless, they wrote a note of caution stating that a ''truly very small amount of splash in the fractionation experiment would carry 40 Ar into the vapor lowering the observed fractionation factor in the observed direction.'' In fact, and in contrast to this, a comparison between VPIE data and LVIFF data taken from Boato et al 23 would lead to the opposite conclusion: ln ␥ ϱ Ϸϩ2ϫ10 Ϫ4 at the triple point decreasing to about ϩ1ϫ10 Ϫ4 at 100 K. The difference between the two sets of LVIFF data and their comparison with ln(f c /f g ) taken from VPIE can be visualized in Fig. 4.…”

Section: Discussionmentioning

confidence: 85%

“…Lee et al, 17 Clusius et al, [18][19][20] and Boato et al 21 reported vapor pressure isotope effects ͑VPIE͒ for isotopically enriched samples of argon, while liquid-vapor isotope fractionation factors ͑LVIFF͒ were determined by Phillips et al 22 and Boato et al 23 As for the theory, the most successful interpretations of the excess properties of isotopic mixtures are due to Jancsó and Van Hook, 24 Singh and Van Hook, 25 and Calado et al 9 They constitute a natural extension of the theory of isotope effects of Bigeleisen 26 and of the theory of Prigogine et al [27][28][29] for isotopic mixtures. In the case of the mixture of the argon isotopes the analysis can focus exclusively on the intermolecular potential; complications from hindered rotation and from internal vibrational degrees of freedom do not exist and, therefore, theory can be applied in its most rigorous form: Singh and Van Hook 25 attempted to estimate excess properties from the difference between VPIE and LVIFF: contrary to expectations, they obtained a negative value for the activity coefficient of 36 Ar at infinite dilution in 40 Ar.…”

Section: Introductionmentioning

confidence: 99%

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Evidence for nonideality in the fundamental liquid mixture (36Ar+40Ar)

Rebelo¹,

Dias²,

Lopes³

et al. 2000

The Journal of Chemical Physics

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Positive excess molar Gibbs energies were detected in liquid mixtures of ( 36 Arϩ 40 Ar) using a high-accuracy double differential manometric technique. The vapor pressure differences between a mixture of ( 36 Arϩ 40 Ar) and 40 Ar and between 36 Ar and 40 Ar were measured simultaneously with the vapor pressure of 40 Ar. Four different mixtures were selected and 80 temperatures were chosen in the 85-96 K temperature range. The results show that the vapor pressure of an equimolar liquid mixture is greater than what would be expected if the solution were strictly ideal, by approximately 2.5 Pa in the 85-96 K temperature range. The calculated excess Gibbs energy for the equimolar mixture at 85 K is G 1/2 E ϭ(0.021Ϯ0.004) J mol Ϫ1 . For the excess molar enthalpy a value of H 1/2 E ϭ(0.12Ϯ0.04) J mol Ϫ1 was found. The corresponding deviations from Raoult's law are therefore extremely small ͑3 to 4 orders of magnitude smaller than those typically found in binary mixtures of nonisotopic constituents͒. The evidence of nonideal behavior in such a fundamental and simple system is relevant for the interpretation of the properties of liquid mixtures of more general importance. The pitfalls of the determination of activity coefficients through the comparison between vapor pressure isotope effect data and liquid-vapor isotope fractionation factors are discussed in some detail. The results were used to test three theoretical models, namely, the vdW-1 fluid theory, the 1cLJ perturbation theory, and the statistical theory of isotope effects in mixtures. While the first two proved to be inadequate, the isotope effect theory agrees reasonably well with experiment. The excess Gibbs energy of monatomic isotopic mixtures are related with the molar volume isotope effect and with the mean Laplacian of the potential energy in the liquid phase.

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Section: Discussionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Evidence for nonideality in the fundamental liquid mixture (36Ar+40Ar)

Rebelo¹,

Dias²,

Lopes³

et al. 2000

The Journal of Chemical Physics

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“…A better estimate of the uncertainty in temperatemperature of the thermocouple junction was deter-ture may be made with the single stage separation factor mined from the NBS Standard Thermocouple Tables. experimentally determined by Boato et al21 This esti-The accuracy of the thermocouple temperature meas-mate indicates that the temperature values determined…”

mentioning

confidence: 66%

Ultrasonic Velocity and Attenuation in Liquid Neon

Larson

Naugle

Adair

1971

The Journal of Chemical Physics

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A new simple method of ultrasonic velocity and attenuation measurement in a high absorption liquid J. Acoust. Soc. Am. 81, 947 (1987); 10.1121/1.394574 Ultrasonic velocity and attenuation in mammalian tissuesThe velocity and attenuation of 30-MHz sound waves were measured in liquid neon from 25 to 37°K at pressures to 28 kg/em'. The values of the velocity, extrapolated to the vapor pressure curve, are from 1.5% higher at 25°K to 0.4% higher at 32°K than corresponding values reported for 2-GHz sound waves. This negative dispersion is in agreement with recent predictions by Fleury and Boon. Values of the attenuation exceed the classical values calculated from the Navier-Stokes equation. This excess attenuation is attributed to a volume viscosity of the same magnitude as the shear viscosity. No anomaly in the temperature dependence of either velocity or attenuation was observed near the temperature where an anomaly has been reported for thermal conductivity, shear viscosity, and hypersonic velocity.

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“…These corrections were applied using the thermodynamic data given by McCarty and Stewart [9]. The term in square brackets ranged from 0-970 at 24.7 K to 0"595 at 38-6 K. The isotope separation factor has also been measured directly by mass spectrometric analysis of samples withdrawn from a system at equilibrium by Boato et al [14][15][16]. This work is in good agreement with In a values obtained from the work of Bigeleisen and Roth.…”

Section: Radial Distribution [Unctionsmentioning

confidence: 99%