D/H and 18O/16O fractionation factors between vapor and liquid water.

Abstract

Analysis of the data of KAKIUCHI and MATASUO (1979) and other work on H/D fractionation factors for water(liq) F water(vapor) verifies earlier observations of the ratio, 1nRDOD/1nRHOD = 7 = 1.91 ± 0.02, (1nRDOD = ln(PHOH/PDOD), 1nRHOD = ln(PHOH/PHOD)). Analysis of KM's data on 180/ 160 fractionation according to the method of JANCSO and VAN HOOK (1978a) shows good agreement between fractionation factors and measurements of vapor pressures of separated isotopes. A significant volume dependence for the high frequency OH stetching motions in water is verified.

Isotope effects in solution thermodynamics: excess properties in solutions of isotopomers

“…This straightforward prediction results from the fact that A VIV is of opposite sign for H/D (AV/V = -1.7 X 10'3) and 180/160 substitution (AV/V = 1.5 X 1043). 24 The magnitude of these effects, and their opposite signs, have been rationalized by Dutta-Choudhury and Van Hook51 in terms of the vibrational dynamics of the condensed phase. Spectroscopic data required for the calculations in Table VII were available from Walrafen and Abebe.81 Notice that if the excess free energies were calculable from the PBB approach, or one of its modifications, i.e., from the contribution of the external degrees of freedom alone, Gez = -(V-V')2/2ff'V'RT, it would be impossible to rationalize the opposite signs experimentally observed for the quantity [In a -In (P/P)].…”

“…Mex(V0,r = RT In (7") = -fjy°P{V)dV = (dA/dV)TdV (24) which for the commonly employed oscillator model can be rewritten Mex((/°')" = RT In 7" = -RT §ya y^(d In ql/du^idujdV)TdV (25) where, as always, u, = hcvJkT. Given detailed knowledge of the volume dependence of all 3n vibrational frequencies, eq 25 may be straightforwardly evaluated.…”

Novel Corresponding-States Principle Approach for the Equation of State of Isotopologues: H218O as an Example

“…The difference between the VPIE and the liquid−vapor isotope fractionation factor at room temperature does not exceed 0.03‰ according to eq 42. The previous estimate (0.5%) by Jakli and Van Hook seriously overestimated this difference because they did not take into account the contribution from the potential part of the free energy in their calculation for the term P d V at room temperature.…”