Solubilities Of He Research Articles

Calculations of solubilities of pure noble gases and He–CO2/CH4/N2 gas mixtures in aqueous solutions with accurate thermodynamic models

Determining solubilities of pure noble gases and He–CO2/CH4/N2 gas mixtures in aqueous solutions is essential for various applications of noble gases in geological processes and for understanding the migration and accumulation of helium. This study developed two thermodynamic models for calculations of solubilities of five pure noble gases (i.e. He, Ne, Ar, Kr, and Xe) and He–CO2/CH4/N2 gas mixtures in water and in aqueous NaCl solution. The first model is constructed by extending the improved SAFT-LJ equation of state (EOS) to five binary H2O-noble gas systems and four ternary systems (i.e. H2O–He–NaCl, H2O–He–CO2, H2O–He–CH4, and H2O–He–N2). Both the non-ideality of aqueous phase and that of vapor phase of these systems were described using the improved SAFT-LJ EOS (φ-φ model). The second model is developed by modifying the gas solubility model proposed by Duan and his coworkers (one type of γ-φ model). The Pitzer theory was used to describe the non-ideality of aqueous phase and the improved SAFT-LJ EOS was used to describe the non-ideality of vapor phase. Both binary adjustable parameters of the improved SAFT-LJ EOS and parameters of the modified solubility model for pure gas were evaluated from experimental solubility data for pure gas. Both models are predictive for solubilities of gas mixtures since there is no need to evaluate their parameters from solubility data of gas mixtures.Comparisons of calculations of two models with experimental data show that both models can well represent solubilities and Henry's coefficients of five noble gases in pure water, as well as the solubility of He in aqueous NaCl solutions over a wide P-T range (273–600 K, 1–2000 bar for the solubility of He in water). The absolute average deviation of the improved SAFT-LJ EOS from experimental solubility data for five noble gases in pure water is 3.14% and that of the modified solubility model is 2.21%. Predictions of the improved SAFT-LJ EOS for Henry's coefficients for He in the He–CO2–H2O system are consistent with available experimental data. According to predictions of the improved SAFT-LJ EOS, Henry's coefficient for He in the He–CO2–H2O system is always lower than that in the He–H2O system at the same depth. Within 0–5 km depth, He solubility of He–CO2 gas mixture is much greater than that of pure He at the same depth and He partial pressure, He solubility of He–N2 mixture is a little greater than that of pure He, and He solubility of He–CH4 mixture is between that of He–CO2 mixture and that of He–N2 mixture. A computer program for calculations of solubilities of pure noble gases and He–CO2/CH4/N2 gas mixtures in pure water and in aqueous NaCl solutions can be obtained from the corresponding author via email.

Modelling sorption and diffusion of NF3 and CF4 in Teflon AF perfluoropolymer membranes

Molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations with Teflon AF2400 and Teflon AF1600 predicted diffusivities and solubilities of He and N2 that corresponded reasonably with available experimental data. The results of the MD simulations further showed that NF3 had a higher diffusivity than CF4 in both polymers and that the NF3/CF4 diffusion selectivity was 67% higher in Teflon AF1600 compared to Teflon AF200. However, because the GCMC simulations failed to offer a conclusive answer to the role of the solubility selectivity w.r.t. NF3 and CF4, the non-equilibrium lattice fluid (NELF) model was used to further evaluate this aspect. Consequently, the combined NF3/CF4 diffusion and solubility selectivity values predicted permeability selectivities that corresponded well with the previously reported experimental data, which confirmed that a lower FFV resulted in an increased NF3/CF4 solubility and diffusion selectivity.

An observed link between lithophile compositions and degassing of volatiles (He, Ar, CO2) in MORBs with implications for Re volatility and the mantle C/Nb ratio

There are systematic variations between relative noble gas abundances and lithophile tracers such as 87Sr/86Sr, εNd and La/Sm in a suite of basaltic glasses from the South East Indian Ridge (SEIR). 4He/40Ar⁎ (where 40Ar⁎ is 40Ar corrected for atmospheric contamination) correlates positively with 87Sr/86Sr and La/Sm but anticorrelates with εNd. The large range in 4He/40Ar⁎ observed in the glasses is due to fractionation during magmatic degassing caused by the very different solubilities of He and Ar in silicate liquids, whereas 87Sr/86Sr, εNd, La/Sm, etc. are insensitive to magmatic processes but rather reflect mantle heterogeneity. Thus, there is a curious situation in this suite of basalts where tracers of mantle heterogeneity (87Sr/86Sr, εNd, La/Sm, etc.) correlate with a tracer of magmatic volatile processes (4He/40Ar⁎).Here, we propose that “enriched” mantle (with high La/Sm and 87Sr/86Sr, low εNd) also has a higher C concentration than “depleted” mantle. Magmas derived from enriched mantle will therefore have higher initial C concentrations, leading to a greater fraction of CO2 degassed and thus a higher 4He/40Ar⁎ ratio on eruption. Simple solubility-determined fractional degassing models show that the range in 4He/40Ar⁎ observed in SEIR basaltic glasses can be generated if the mantle C concentration varies by a factor of 2 over the length of the ridge, consistent with independent estimates of C concentration heterogeneity in the MORB mantle. The correlations between lithophile tracers and 4He/40Ar⁎ can be reproduced by mixing between a depleted endmember with 87Sr/86Sr = 0.70275, εNd = 8.2 and [C] = 12 ppm and an enriched endmember with 87Sr/86Sr = 0.70360, εNd = 5 and [C] = 24 ppm, followed by degassing.The proposed degassing model allows us to estimate the initial C concentration (i.e. prior to degassing) of each SEIR basalt (for which Sr or Nd isotopes are available); using independent Nb concentration data (Mahoney et al., 2002), we show that C/Nb ratios prior to degassing along the SEIR are relatively constant, probably with a C/Nb ratio of 200±100. However, although the constancy of C/Nb in these samples is a robust conclusion, the estimated C/Nb ratio itself is model dependent.We also use these data to evaluate volatility of Re during degassing of MORBs; Re is known to be moderately volatile during subaerial and shallow marine volcanism, although it is not known if this element is also volatile at conditions appropriate to MORB emplacement. Although there is a (poor) correlation between Re/Yb (Yb being a non-volatile element of similar apparent bulk compatibility to Re) and 4He/40Ar⁎ in these samples, it is more likely that this correlation results from Re/Yb variation in the mantle source and is not due to loss of Re during magmatic degassing.

Low solubility of He and Ar in carbonatitic liquids: Implications for decoupling noble gas and lithophile isotope systems

In order to asses the importance of carbonatitic liquids in transporting noble gases in the mantle, the solubilities of He and Ar in carbonatitic liquids were estimated from analyses of calcium–potassium carbonate glasses that had been synthesized at 1 bar and temperatures between 850 and 950 °C under He or Ar enriched atmospheres. Despite poor reproducibility related to difficulties synthesizing carbonatite glass, we have been able to estimate He and Ar solubilities in carbonatite liquids to be 1 × 10 −8 and 2 × 10 −9 mol g −1 at 1 bar respectively (with ⩾50% uncertainty). Despite the significant uncertainties on these estimates, it is clear that the noble gases are not massively soluble in carbonatite liquids (within error, these solubilities are identical to their equivalent solubilities in tholeiitic melts). Assuming the results of these low pressure experiments can be applied to mantle conditions, it seems unlikely that carbonatite metasomatism per se transports noble gases within the mantle. It is nevertheless possible that partitioning of lithophile trace elements (including the important radioelements, U, K and Th) and noble gases between a carbonatitic melt and a silicate melt could effectively decouple lithophile and noble gas isotope systematics because the carbonatitic melt expressedly does not transport noble gases, yet is known to efficiently transport incompatible trace elements.

Degassing and contamination of noble gases in Mid‐Atlantic Ridge basalts

New He, Ne, Ar and CO2 stepped‐crushing data from the Mid‐Atlantic Ridge show that contamination of basalts by atmospheric noble gases involves three or more components: unfractionated air, fractionated air with high 36Ar/22Ne (≥45) and fractionated air with low 36Ar/22Ne (≤5). In addition, the magmatic noble gases trapped in these basaltic glasses are variably fractionated such that 4He/40Ar* (where the asterisk indicates corrected for atmospheric contamination based on all 36Ar being atmospheric in origin) is in the range 3–12. Single samples have a range in 4He/40Ar* with the highest ratios in the final crush steps, consistent with the most fractionated (highest 4He/40Ar*) volatiles trapped in the smallest vesicles. It is not possible to distinguish between batch and Rayleigh degassing mechanisms. The complexities of the contamination and magmatic fractionation processes means that it is not possible to estimate 40Ar/36Ar of the mantle source to these basalts other than it must be higher than the highest ratio measured (26,200 ± 5200). Noble gas/CO2 ratios are also variable. While some CO2 adsorption during crushing exaggerates the variations in He/CO2 and Ar/CO2, we show that it is not possible to account for the entire variation as an analytical artefact: some of the variation is present in the vesicles. Variations in He/CO2 cannot be attributed to solubility controlled degassing because of the broadly similar solubilities of He and CO2 in tholeiitic magmas. The large range in He/CO2 in these glasses (factor of 10) is not accompanied by indications of major changes in melting regime or source region chemistry, therefore is thought to reflect late‐stage (magmatic) fractionation of CO2 from the noble gases. It is not possible to identify an explicit mechanism, although both CO2 reduction (e.g., to hydrocarbons or graphite) and kinetic CO2‐noble gas fractionation could account for the variations.

Mechanisms of magmatic gas loss along the Southeast Indian Ridge and the Amsterdam –St. Paul Plateau

New analyses of He, Ne, Ar and CO2 trapped in basaltic glasses from the Southeast Indian Ridge (Amsterdam–St. Paul (ASP) region) show that ridge magmas degas by a Rayleigh distillation process. As a result, the absolute and relative noble gas abundances are highly fractionated with 4He/40Ar* ratios as high as 620 compared to a production ratio of ∼3 (where 40Ar* is 40Ar corrected for atmospheric contamination). There is a good correlation between 4He/40Ar* and the MgO content of the basalt, suggesting that the amount of gas lost from a particular magma is related to the degree of crystallization. Fractional crystallization forces oversaturation of CO2 because CO2 is an incompatible element. Therefore, crystallization will increase the fraction of gas lost from the magma. The He–Ar–CO2–MgO–TiO2 compositions of the ASP basalts are modeled as a combined fractional crystallization–fractional degassing process using experimentally determined noble gas and CO2 solubilities and partition coefficients at reasonable magmatic pressures (2–4 kbar). The combined fractional crystallization–degassing model reproduces the basalt compositions well, although it is not possible to rule out depth of eruption as a potential additional control on the extent of degassing. The extent of degassing determines the relative noble gas abundances (4He/40Ar*) and the 40Ar*/CO2 ratio but it cannot account for large (>factor 50) variations in He/CO2, due to the similar solubilities of He and CO2 in basaltic magmas. Instead, variations in CO2/3He (C/3He) trapped in the vesicles must reflect similar variations in the primary magma. The controls on C/3He in mid-ocean ridge basalts (MORBs) are not known. There are no obvious correlated variations between C/3He and tracers of mantle heterogeneity (3He/4He, K/Ti etc.), implying that the variations in C/3He are not likely to be a feature of the mantle source to these basalts. Mixing between MORB-like sources and more enriched, high 3He/4He sources occurs on and near the ASP plateau, resulting in variable 3He/4He and K/Ti compositions (and many other tracers). Using 4He/40Ar* to track degassing, we demonstrate that mixing systematics involving He isotopes are determined in large part by the extent of degassing. Relatively undegassed lavas (with low 4He/40Ar*) are characterized by steep 3He/4He–K/Ti mixing curves, with high He/Ti ratios in the enriched magma (relative to He/Ti in the MORB magma). Degassed samples (high 4He/40Ar*) on the other hand have roughly equal He/Ti ratios in both end-members, resulting in linear mixing trajectories involving He isotopes. Some degassing of ASP magmas must occur at depth, prior to magma mixing. As a result of degassing prior to mixing, mixing systematics of oceanic basalts that involve noble gas–lithophile pairs (e.g. 3He/4He vs. 87Sr/86Sr or 40Ar/36Ar vs. 206Pb/204Pb) are unlikely to reflect the noble gas composition of the mantle source to the basalts. Instead, the mixing curve will reflect the extent of gas loss from the magmas, which is in turn buffered by the pressure of combined crystallization–degassing and the initial CO2 content.

Gas sorption and characterization of poly(ether-b-amide) segmented block copolymers

The solubilities of He, H2, N2, O2, CO2, CH4, C2H6, C3H8, and n-C4H10 were determined at 35°C and pressures up to 27 atmospheres in a systematic series of phase separated polyether–polyamide segmented block copolymers containing either poly(ethylene oxide) [PEO] or poly(tetramethylene oxide) [PTMEO] as the rubbery polyether phase and nylon 6 [PA6] or nylon 12 [PA12] as the hard polyamide phase. Sorption isotherms are linear for the least soluble gases (He, H2, N2, O2, and CH4), convex to the pressure axis for more soluble penetrants (CO2, C3H8, and n-C4H10) and slightly concave to the pressure axis for ethane. These polymers exhibit high CO2/N2 and CO2/H2 solubility selectivity. This property appears to derive mainly from high carbon dioxide solubility, which is ascribed to the strong affinity of the polar ether linkages for CO2. As the amount of the polyether phase in the copolymers increases, gas solubility increases. The solubility of all gases is higher in polymers with less polar constituents, PTMEO and PA12, than in polymers with more polar PEO and PA6 units. CO2/N2 and CO2/H2 solubility selectivity, however, are higher in polymers with higher concentrations of polar repeat units. The sorption data are complemented with physical characterization (differential scanning calorimetry, elemental analysis, and wide angle X-ray diffraction) of the various block copolymers. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2463–2475, 1999

Gas Solubilities in Aqueous Solutions of Organic Substances

The solubilities of He, N2, O2, CH4, and CO2 in aqueous solutions of glycerol, acetic acid, glucose, sucrose, and lactose were measured at 303.2 K. Additional data were generated for CO2 at 293.2 K and 323.2 K. The present results and literature data were analyzed to develop an empirical model. The parameter set allows predictions for 15 gases and 63 organic substances at temperatures between 273 K and 343 K.

Noble gas solubilities in silicate melts and glasses: New experimental results for argon and the relationship between solubility and ionic porosity

New measurements of the solubility of Ar in basaltic, rhyolitic, orthoclasic, and albitic melts and glasses ar Ar pressures of 250–10,000 bar and temperatures of 400–1300°C are presented and combined with other solubility measurements for a wider range of melt compositions to parameterize the effects of pressure, temperature, and melt composition on Ar solubility. Argon solubility in melts and glasses is roughly linear with Ar pressure under these conditions. At near-liquidus temperatures, solubility in melts is approximately independent (within ∼ 10%) of temperature, while some results below 600–700°C show an increase in solubility with decreasing temperature, perhaps reflecting differences in the nature of Ar solubility in glasses and melts. There is also a positive, linear correlation between the “ionic porosity” of melt and the logarithm of Ar solubility. This correlation is better than previously noted correlations between inert gas solubility and melt density and volume, and provides a useful means of predicting how Ar solubility varies with melt composition. The solubilities of He, Ne, Kr, and Xe are also positively correlated with ionic porosity, but are increasingly sensitive to ionic porosity as the size of the gas atom increases, suggesting that with more efficient packing of the melt structure the availability of sites that can incorporate inert gas atoms decreases more rapidly for larger atoms than for smaller atoms. Comparison of inert gas solubilities with those of molecular CO 2 and molecular H 2O in rhyolitic melts shows that solubilities decrease in the order H 2O mol ⪢ He > Ne > Ar > CO 2,mol ∼ Kr > Xe. The much higher solubility of molecular H 2O compared to the other neutral gas species (and molecular CO 2) suggests that it is not merely passively occupying interstitial “holes” in the melt structure as is thought to be the case for the rare gases (and likely for molecular CO 2), but rather it is stabilized in the melt structure by chemical bonds (e.g., by hydrating cations or through hydrogen bonds).

Solubility of 13 nonpolar gases in deuterium oxide at 15?45�C and 101.325 kPa. Thermodynamics of transfer of nonpolar gases from H2O to D2O

Using a computer controlled version of the Ben-Naim and Baer apparatus, the solubilities of He, Ne, Ar, Kr, H2, D2, N2, O2, CH4, C2H6, C3H8, CF4, and SF6 in D2O (and the solubility of CF4 in H2O) were determined at four temperatures in the range 288 to 318 K and at a partial pressure of gas of 101.325 kPa. The precision of the measurements was 0.3–1.0%. The experimental data were processed using rigorous thermodynamic methods and were fitted to the Clarke-Glew-Weiss equation. Changes in the thermodynamic properties on solution were calculated from the smoothing equations. Scaled-particle theory (SPT) was used to determine the Lennard-Jones (6,12) pair potential parameters for D2O: σ=0.275 nm and e/k=83.4 K. Experimental mole fraction solubilities and thermodynamic functions at 298.15 K were compared with results calculated using the SPT. The thermodynamic transfer functions of gases from H2O to D2O were calculated. The changes induced by the solvation process on the structure of water were estimated from the Gibbs energy of transfer and the difference in the hydrogen bond energies for D2O and H2O.

Behavior of helium release from simulated radioactive waste glasses.

Rates of He release from two kinds of simulated high-level radioactive waste glasses were measured in the temperature range from 573 to 753K by a mass spectrometric method. Diffusion coefficients of He in the glasses were determined from the fractional release data. The diffusion coefficients were given as a function of temperature by the equations: D/(m2·s−1) = 2.3 × 10−6 exp (−71.1±2.1 kJ/RT) for P0798 glass =9.8 × 10−7 exp (−60.2±2.1 kJ/RT) for P0504 glass. In addition, solubilities of He in the glasses were determined from the measurement of the total amount of released He and found to be S/(atoms/m3) = 2.0 × 1022 for P0798 glass =2.2 × 1022 for P0504 glass. at 693 K and 1.7 × 105 Pa He. The diffusivities and solubilities of He in the glasses were, respectively, several and an order of magnitude lower than silica, alkali silicate and Pyrex glasses, which properties are notable for the radioactive waste glasses.

The solubility of noble gases in crude oil at 25–100°C

The solubility of the noble gases He, Ne, Ar, Kr and Xe was measured in two typical crude oils at temperatures of 25–100°C. The oil samples were obtained from the Elk Hills oil field located in southern San Joaquin Valley, California. The experimental procedure consisted of placing a known amount of gas with a known volume of crude oil in a stainless steel hydrothermal pressure vessel. The vessel was housed inside an oven and the entire unit rotates providing continuous mixing. The amount of gas dissolved in oil at a measured temperature and partial pressure of gas was used to calculate the solubility constants for these gases. Results show that the solubility of He and Ne in both oils is approximately the same; solubility then increases with atomic mass, with the solubility of Xe at 25°C being two orders of magnitude higher than that of He. The gas solubilities are somewhat higher in the lower density (higher API gravity) oil. The solubility of Ar is approximately constant in the range of temperatures of this study. The solubilities of He and Ne increase, but those of Kr and Xe decrease with increasing temperatures. Solubilities of noble gases in crude oil are significantly higher than their solubilities in water. For example, the solubilities of He and Xe at 25°C in the light oil of this study are, respectively, 3 and 24 times higher than their solubilities in pure water, and they are 15 and 300 times higher than in a brine with a salinity of 350,000 mg/l dissolved solids. These large and variable differences in the solubilities of noble gases in oil and water indicate that, in sedimentary basins with oil, these gases must be partitioned between oil, water and natural gas before they are used to deduce the origin and residence time of these fluids.

The solubility of noble gases in water and in NaCl brine

A direct-sampling, mass-spectrometric technique has been used to measure simultaneously the solubilities of He, Ne, Ar, Kr, and Xe in fresh water and NaCl brine (0 to 5.2 molar) from 0° to 65 °C, and at 1 atm total pressure of moist air. The argon solubility in the most concentrated brines is 4 to 7 times less than in fresh water at 65 °C and 0°C, respectively. The salt effect is parameterized using the Setschenow equation. ln [ β i o(T) β i(T) = MK i M(T) where M is NaCl moiarity, β i o ( T) and β i ( T) the Bunsen solubility coefficients for gas i in fresh water and brine, and K i M ( T) the empirical salting coefficient. Values of K i M ( T) are calculated using volumetric concentration units for noble gas and NaCl content and are independent of NaCl molarity. Below about 40°C, temperature coefficients of all K i M are negative. The value of K He M is a minimum at 40°C. K Ar M decreases from about 0.40 at 0°C to 0.28 at 65 °C. The absolute magnitudes of the differences in salting coefficients (relative to K Ar M ) decrease from 0° to 65°C. Over the range of conditions studied, all noble gases are salted out, and K He M ≲ K Ne M < K Ar M < K Kr M < K Xe M . From the solubility data, we calculated Δ G 0 tr , Δ S 0 tr , Δ H 0 tr and Δ C O p,tr for the transfer of noble gases from fresh water to 1 molar NaCl solutions. At low temperatures Δ S 0 tr , is positive, but decreases and becomes negative at temperatures ranging from about 25°C for He to 45°C for Xe. At low temperatures, the dissolved electrolyte apparently interferes with the formation of a cage of solvent molecules about the noble gas atom. At higher temperatures, the local environment of the gas atom in the brine appears to be slightly more ordered than in pure water, possibly reflecting the longer effective range of the ionic fields at higher temperature. The measured solubilities can be used to model noble gas partitioning in two-phase geothermal systems at low temperatures. The data can also be used to estimate the temperature and concentration dependence of the salt effect for other alkali halides. Extrapolation of the measured data is not possible due to the incompletely-characterized minima in the temperature dependence of the salting coefficients. The regularities in the data observed at low temperatures suggest relatively few high-temperature data will be required to model the behavior of noble gases in high-temperature geothermal brines.

The solubility of gases in liquids 8. Solubility of He, Ne, Ar, Kr, CO 2, CH 4, CF 4, and SF 6 in o-, m-, and p-xylene at 283 to 313 K

The solubilities of He, Ne, Ar, Kr, CO 2, CH 4, CF 4, and SF 6 in the three isomeric xylenes have been determined at atmospheric pressure in the range 283 to 313 K. From the experimental results partial molar Gibbs energy, enthalpy, and entropy of solution for 1 atm partial pressure of gas and 298.15 K have been calculated. These values have been compared with results obtained through application of the scaled particle theory to gas solubilities. Agreement is generally satisfactory.

The solubility of gases in liquids 2. The solubility of He, Ne, Ar, Kr, N 2, O 2, CO, and CO 2 in 2-methyl-1-propanol (1 to 55 °C)

The solubilities of He, Ne, Ar, Kr, N2, O2, CO, and CO2 in isobutanol (2-methyl-1-propanol) were determined at atmospheric pressure in the range 1 to 55°C. The scaled particle theory gave very satisfactory results for the calculation of solubility and thermodynamic functions for the systems studied. The solubilities were related to transport through the cell membrane via the Collander equation which relates permeabilities to partition coefficients.

Primordial noble gases in separated meteoritic minerals—I

Magnetite and a layer-lattice silicate from the Orgueil carbonaceous chondrite show strikingly different noble gas patterns. Magnetite contains He, Ne and Ar in essentially solar proportions, with some excess Kr and Xe. Isotopic ratios are typically solar: Ne 20 Ne 22 = 12.5 , He 3 He 4 = (3.8 ± 0.4) × 10 −4 ; but Xe 129 Xe 132 is quite high, 2.0 to 6.6. He 4 Ne 20 is 730, which is probably close to the true solar ratio. Silicate contains planetary gas, with Ne 20 Ne 22 = 8.2 , He 3 He 4 = (1.4 ± 0.4) × 10 −4 , and Xe 129 Xe 132 = 1.018 ± 0.003 . The Ne 21 radiation age of the magnetite, 10.7 m.y., is higher than that of the bulk meteorite, 4.5 m.y., which implies substantial loss of cosmogonic Ne 21 from silicate. Presumably the radiation ages of other Cl chondrites are too low by similar factors. The primordial component in magnetite is loosely bound, and may represent trapped solar wind. The gas in silicate is more tightly held and was probably absorbed from the solar nebula at 350 ± 50° K. Data on low-temperature solubilities of He, Ne and Ar suggest that the observed amounts and elemental fractionations of planetary gas can probably be explained by equilibrium solubility. The isotopic features of planetary gas require an additional process, such as production of Na 22 by charged-particle irradiation.

The solubilities of seven gases in olive oil with reference to theories of transport through the cell membrane.

AbstractThe solubilities of He, Ne, Ar, N2, O2, CO and CO2 in olive oil have been determined in the temperature range 24–56 C. The gas solubility apparatus was a considerably improved version of the one reported by Morrison and Billett and gave a precision, depending on the gas solvent system of ±0.2% to ±1.0%. Plots of log L, the Ostwald coefficient, and log α, the Bunsen coefficient, against 1/TK were linear and showed a small temperature dependence for CO2. The enthalpy and entropy changes corresponding to the solution process were calculated. The partition coefficients of the gases between olive oil and water were calculated using reported values for the solubility of the gases in water. These results have been used to test and extend the Meyer‐Overton theory of transport through the cell membrane.

Thermodynamic Properties of Gases in Propellants and Oxidizers. I. Solubilities of He, N2, O2, Ar, and N2O3 in Liquid N2O4

Thermodynamic Properties of Gases in Propellants and Oxidizers. I. Solubilities of He, N₂, O₂, Ar, and N₂O₃ in Liquid N₂O₄

The permeability of poly(ethyl methacrylate) to gases and water vapor

AbstractThe permeabilities, diffusivities and solubilities of He, Ne, A, O2, N2, Kr, CO2, H2S, and H2O in poly(ethyl methacrylate) have been measured above and below the glass temperature. Water showed a small increase in solubility when the polymer was heated above the glass temperature. Water also showed anomalous behavior in that the solubilities calculated from the permeability constants and the time‐lag diffusion constants are much less than those measured by direct weighing. The behavior had been found previously with other polymers and has been interpreted in terms of the clustering of water molecules in the polymer. The Arrhenius plots of the permeability and diffusion constants for water showed the change in slope at the glass temperature reported to occur with many gases and vapors through other polymers. The gases, however, showed no change in slope even with large molecular size gases such as silicon tetrafluoride and sulfur hexafluoride. The results found with water are interpreted as due to the plasticizing effect of the penetrant when the polymer is above the glass temperature. In the case of the gases, the lack of a transition effect is interpreted in terms of the relative sizes of the gas molecule and the average hole she of the polymer. The energies of activation for diffusion were found to be proportional to the 1.6 power of the molecular diameter of the; penetrants, i.e., intermediate between that found for rubber and for both poly(vinyl acetate) and poly(ethylene terephthalate).

Solubility of Noble Gases in Molten Fluorides. I. In Mixtures of NaF–ZrF4 (53–47 Mole %) and NaF–ZrF4–UF4 (50–46–4 Mole %)

Solubilities of He, Ne, Ar, and Xe were determined at pressures from 0.5 to 2 atmospheres in NaF-- ZrF/sub 4/ (53--47 mole %) at 600, 700, and 800 d . The solubilities increase linearly with gas pressure, decrease with increasing atomic weight of the solute and increase with increasing temperature. Henry's law constarts in moles of solute/(cm/sup 3/ solution)(atmosphere) at 600 d are 21.611 x10/sup -8/, 11.3 plus or minus 0.3 x10/sup -8/, 5.06 plus or minus 0.15 x 10/sup -8/, and 1.94 plus or minus 0.2 x 10/sup -8/ while heats of solution are 6.2, 7.8, 8.2, and 11.1 kcal/mole for He, Ne, Ar, and Xe, respectively. Solubilities and heats of solution for He and Xe in NaF--ZrF/sub 4/ --UF/sub 4/ (50--46--4 mole % are very similar to the values obtained with these gases in the NaF-- ZrF/sub 4/ mixture. (auth)