Physical properties of heavy-oxygen water. Part 2.—Vapour pressure

Abstract

A method has been developed for measuring small differences between the vapour pressures of two samples. V.p. differences were determined between water samples with a high concentration of oxygen-18 ( H 2 0 1 8 and D 2 0 1 8 ) and samples with a low concentration in the temperature range 15-90°C. Differences between the vapour pressures of water containing -55 % 0 1 7 and samples containing high concentrations of 0 1 6 and 0 1 8 respectively, in the range 40-90°C, have also been measured. Using these results, vapour pressure ratios between the pure isotopic species were calculated.* i.e. the ratio of vapour pressure of water containing 100 % oxygen-16 to that of labelled water.

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

“…For 180/160 effects the calculated difference at 32°, 6 ± 2 X 10-4 unit, is in satisfactory agreement with the observed differences between the smoothed lna measurements of KAKIUCHI and MATSUO (1979) or M AJOUBE (1971) (which are within 0.0001 unit of each other) and the JAKLI and STASCHEWSKI (1977) or SZAPIRO and STECKEL (1967) In R measurements; (lna 1nR)exptl = 4 ± 1 X 10-4 unit.…”

“…For the H/D system, in addi data reported by SzAPIRO and STECKEL (1967) tion to their own work on Ina, they cite values and JAKLI and STASCHEWSKI (1977).…”

13C and 33,34S isotope effects on the vapour pressure of liquid carbon disulfide

“…We therefore feel confident that our treatment of this point is valid. The most precise data (10,11) for the systems in [4] and [5] show some slight departure from the rule of the geometric mean. However these deviations are not large, and we feel the rule to be sufficiently precise for our purpose-, which is to calculate the value of R4,2 from that for R1,2 Thus:…”

Direct measurements of D/H and 18O/16O fractionation factors between vapor and liquid water in the temperature range from 10 to 40.DEG.C.

“…(1) measurements of vapor pressure of isotopic temperature of the vapor-liquid equilibrium was molecules over liquid phase (e.g., for aD, JONES, fixed by circulating water through thermostat A 1968, and for a180, SZAPIRO and STECKEL, 1967, at the temperature of T, and the equilibration JAKLI and STASCHEWSKI, 1977) vessel and the vapor sampler were immersed in (2) measurements on D/H and/or 180/160 of thermostat B at the temperature of T'. both vapor and liquid (e.g., for aD, MERLIVAT et The temperature difference (T'-T) was set al ., 1963, andMAJOUBE, 1971, and for a180 , to 7'C and.…”