Gas Saturation Method Research Articles

Measurements on the phase behavior of binary mixtures for modeling the condensation behavior of natural gas: Part III. The system methane + hexadecane

Rijkers, M.P.W.M., Peters, C.J. and De Swaan Arons, J., 1993. Measurements on the phase behavior of binary mixtures for modeling the condensation behavior of natural gas. Part III. The system methane + hexadecane. Fluid Phase Equilibria, 85: 335-345. This paper reports measurements on the solubility of hexadecane in methane at temperatures between 285 and 315 K and at pressures up to 25 MPa. The data were obtained with the gas saturation method, as described in Part I of this series (Rijkers, M.P.W.M., Malais, M., Peters, C.J. and De Swaan Arons, J., 1992. Fluid Phase Equilibria, 71: 143-168). Concentrations between 0.1 and 700 ppm hexadecane in methane (on a molar basis) were measured with, in general, a reproducibility better than 2%. The experimental data are complementary to the bubble-point data of Glaser et al. (Glaser, M., Peters, C.J., van der Kooi, H.J. and Lichtenthaler, R.N., 1985. J. Chem. Thermodyn., 17: 803-815). The latter data were combined with the data reported in this contribution and are presented in a p, T, ( x,y) space diagram, from which the p, T and p, ( x,y) sections can be derived.

The vapour pressures of hydroxides II. TeO(OH) 2

The vaporization of TeO 2 in (steam + oxygen + argon) has been investigated by the gas-saturation method. The results confirm previous findings that a gaseous hydroxide of the formula TeO(OH) 2 is formed in the vapour. No indications for the formation of other species have been found. The results of the present work, given by 1 g K 1 = −(4971±308)(T/K)+(1.228±0.332) are significantly lower than those previously reported.

Thermolabile Kohlenwasserstoffe, 30 Thermische Stabilität und Bildungsenthalpie von 1,1,2,2‐ und 1,1,1,2‐Tetraphenylethan. – Die Stabilisierungsenergien von Benzhydryl‐ und Triphenylmethyl‐Radikalen

Thermolabile Hydrocarbons, 30. ‐ Thermal Stability and Heat of Formation of 1,1,2,2‐ and 1.1,1,2‐Tetraphenylethane. ‐Energy of Stabilisation of Benzhydryl and Triphenylmethyl RadicalsHeats of combustion of symmetrical (3) and unsymmetrical tetraphenylethane (4) were determined by combustion calorimetry: ΔH(c)(3) = ‐ 3249.5 ± 0.8;(4) = ‐ 3252.0 ± 0.6 kcal/mol. Enthalpies of sublimation of 3 (ΔH = 32.7 kcal/mol) and 4 (31.7 kcal/mol) were obtained from vapour‐pressure‐temperature relations, which were determined by a gassaturation method. The resulting heats of formation ΔH(g) (3) = 85.4 ± 1.3 and ΔH(g)(4) = 87.3 ± 0.8 kcal/mol correspond to low strain energies: H, (3) = 1.5 and Hs (4) = 4.6 kcal/mol. The thermolysis reactions above 200°C in solution with thiophenol as a scavenger are clean first order processes. The following activation parameters are obtained from kinetic measurements: ΔH# (3) = 47.3 ± 0.3, (4) = 45.0 ± 0.3 kcal/mol, ΔS# (3) = 12.8 ± 0.5 and (4) = 14.0 ± 0.6 e.u. From the presented thermodynamic and kinetic data the stabilisation energies of the benzhydryl (1) and the trityl radical (2) have been derived by comparison with the corresponding data for the alkanes 7 and 9. As a result 1 is stabilysed by 12.9 ± 0.9 and 2 by 20.0 ± 1.7 kcal/mol, compared with a secondary or tertiary alkyl radical, respectively. Thus the substituent effect of two (or three) phenyl rings in 1 (or 2) is smaller than twice (or thrice) the value for one phenyl group14): 7.8 ± 2.0 for a secondary and 8.4 ± 1.2 kcal/mol for a teriary benzyl radical. This can be explained by steric repulsion between the phenyl rings and steric inhibition of resonance.

4675028 Gas saturation monitoring system and method for controlling condensable fuel added to a gas : Thomas G Chin, Rudy F Klaver, Arthur Alston assigned to Chevron Research Company

4675028 Gas saturation monitoring system and method for controlling condensable fuel added to a gas : Thomas G Chin, Rudy F Klaver, Arthur Alston assigned to Chevron Research Company

Vapour pressure of permethrin

AbstractThe vapour pressures of the separate isomers of permethrin have been determined over a range of temperatures by two laboratories using different versions of the gas saturation method. A statistical analysis of the sets of data from the two laboratories shows no significant differences for the cis isomers but a small difference in the 20°C extrapolated values for the trans isomer exists. However, this difference is discounted as arising from experimental error and the mean values of the estimated vapour pressures at 20°C are given as 2.5 μPa (cis) and 1.5 μPa (trans).

Mesure des pressions de vapeur d'hydrocarbures C 10 A C 18n-alcanes et n-alkylbenzenes dans le domaine 3-1000 pascal

Vapour pressure measurements of high boiling point hydrocarbons (C 10-C 18 n-alkanes and n-alkylbenzenes) were carried out in the range: 10 −1 < P 0 < 10 mm Hg, 50 < t 0 < 250°C. The gas-saturation method for measuring low vapour pressures was used. Trial was made of several equations for the representation of the vapour pressure-temperature relationship. The best extrapolation is given by the Scott and Osborn equation. The experimental data are well correlated by this equation.

Realisation d'un ensemble destine a la mesure de faibles pressions de vapeur (Domaine: 3–1000 Pa)

Equipment is described for measurement of low vapor pressure, P 0, in the range: 3 Pa < P 0 <1000 Pa; 50°C < t < 250°C. A possible error of 1% in P and ± 0.02°C in T were estimated. The inert gas-saturation method was used. The vapor pressure was determined by measuring the saturated vapor concentration in the inert gas using a gas chromatograph. The detector chromatograph was calibrated for the material studied. External calibration was chosen and a special syringe was designed and built for this purpose. The apparatus was designed with the following features: (1) by adapting a sample injection valve the gas phase analysis is simple and very accurate; (2) the use of a differential pressure transducer permits accurate measurement of inert gas pressure. The partial vapor pressure, P i, was measured for several total pressures, P. The extrapolation to P = 0 of the plot log P i, vs. P gave the partial vapor pressure of pure substance. This method was derived from thermodynamic considerations (Poynting effect and non-ideality of gas phase).

Measurement of vapor pressures for coal-related aromatic compounds by gas saturation method.

Measurement of vapor pressures for coal-related aromatic compounds by gas saturation method.

Substituent effects in the VUV absorption spectra of monochlorobenzene and o-, m-, and p-dichlorobenzene

Abstract Gas phase VUV absorption cross sections of chlorobenzene and o -, m -, and p -dichlorobenzene are determined in the energy range from 43 000 to 60 000 cm −1 at 0.3 nm resolution using a gas saturation method. Oscillator strengths for the bands corresponding to transitions to the upper states B 1 B 1 u and C 1 E 1 u of benzene are determined by integration over the respective band regions. The structures of the spectra and the bathochromic shifts of the chlorinated compounds with respect to the parent molecule, benzene, are discussed and compared to those of spectra in solution.

Evaluation of a gas chromatographic method calculating vapor pressures with organophosphorus pesticides

The vapor pressures of 20 organophosphorus pesticides varying widely instructure, polarity and volatility were calculated using a method based upon gas chromatographic (GC) retention data. For seven of the pesticides, vapor pressures were determined experimentally by a standard gas saturation method for comparison with the GC-calculated values. Several experimental variables, including the number of GC temperatures and spread between them, nature of the liquid phase in either packed or capillary columns, and nature of the reference compound, were studied for their influence on the GC method's error. The GC calculation, using a short SE-30 capillary column, single reference compound (methyl parathion), and melting point correction for those test compounds which are solids at room temperature, provided vapor pressures agreeing with an average factor of approximately 4 with experimental vapor pressures. The agreement improved when the comparison was with test compounds which are liquids at room temperature and when the polarity of the GC reference compound approximated that of the test compounds.

Comparison of two gas saturation methods for the determination of the vapour pressure of cypermethrin

AbstractThe vapour pressures of cypermethrin have been determined independently, at elevated temperatures in two different laboratories, by different versions of the gas saturation method. A subsequent statistical analysis showed no significant differences between the two sets of data. The mean of the values, extrapolated to 20°C, is 1.9 × 10−7 Pa (1.4 × 10−9 mmHg). A description of one of the methods, previously unpublished, is included as an appendix.

Determination of polychlorinated biphenyl vapor pressures by a semimicro gas saturation method

Determination of polychlorinated biphenyl vapor pressures by a semimicro gas saturation method

Vapor pressures of some sulfur-containing, coal-related compounds

The need to find alternative energy sources has spawned intensive research and development of processes for coal IC quifaction and gasification. Almost all processes, including those involving coal, expend large amounts of capital on separation. Reliable thermodynamic data are needed for efficient design of coal-processing and separation equipment. Vapor pressure is an important physical property required to perform calculations for the design of separation equipment. I t is desireable to calculate vapor pressures of all components from general correlations rather than to measure new data for each new situation. To generate these correlations, however, we require experimental data for model compounds which resemble molecules that might be found in typical coals and coal products. Coal is of complex structure containing large aromatic rings, some of which contain heteroatoms such as N, 0, and S. Few data are available for these types of compounds, partly because vapor pressures of hlgh-molecular-weight compounds may be too low for measurement by conventional means. Sinke ( 7) and Macknick et al. (2) have shown that a gas-saturation method is suitable for measuring vapor pressures of high-molecular-weight hydrocarbons. Van de Rostyne et al. (3) extended the use of this method to highmolecular-weight compounds containing nitrogen. This work reports vapor pressures of high-molecular-weight, coakelated compounds containing sulfur.

Measurement of vapour pressures of Fenitrothion and Matacil

Vapour pressures of Fenitrothion and Matacil were measured using a gas saturation method. Polyurethane foam was used to trap the volatilized materials from sand and glass surfaces, and Porapak Q for trapping materials volatilized from leaf surfaces. The vapour pressures (VP) were linearly related to the reciprocal temperature by the equation: Log (VP) = 6.3362 − ( 3197.8 T ) for a sand incorporated with Fenitrothion and Log (VP) = 8.8316 − ( 4021.4 T ) for a sand incorporated with Matacil. The greatest vapour loss rates were from sand incorporated with fenitrothion, followed by vapour loss rates from glass surfaces; the least vapour loss rate was from leaf surfaces.

Role of Insect Sex Pheromone in Mating Behavior. : II. An Aspect of Sex Pheromone as a Volatile Material

The saturated vapor pressures of three compounds identified as a sex pheromone of Lepidoptera and related compounds are measured by the "gas-saturation method, " The values of saturated vapor pressure of these materials are 10X-4-10X-1 mmHg at 30°C. Vapor-liquid equilibrium of these pheromonal compounds is discussed in regard to these values for vapor pressure and mole fraction (or weight %).

Solubilities of sparingly soluble gases in aqueous sodium sulfate and sulfite solutions.

Solubilities of oxygen in aqueous sodium sulfate solutions have been measured at an oxygen partial pressure of 1 atm and temperatures of 15, 25 and 35°C by the gas saturation method. The results are not correlated by the empirical Setschenow equation. The estimated solubility of the system at 25°C by the method of van Krevelen et al. is appreciably lower than the observed results. Solubilities of nitrogen in various concentrations of aqueous sodium sulfate and sulfite solutions have been measured at 25°C and nitrogen partial pressure of 1 atm. Solubility of oxygen in aqueous sodium sulfite solutions at 25°C is estimated from the above results. Solubilities of nitrogen and oxygen in aqueous sodium sulfate and sulfite mixed solutions are also discussed.

A method for measurement of vapor pressures of organic compounds below 0.1 Toor Naphthalene as a reference substance

The gas-saturation method for measuring low vapor pressures of organic compounds was modified by converting the organic vapor to CO 2 and monitoring the CO 2 content of the carrier gas, O 2, with an infra-red analyzer. This technique gives instantaneous readings of the vapor pressure and eliminates the long times needed for gravimetric measurements. The vapor pressure of naphthalene was measured and correlated with literature data to derive a reliable relation between vapor pressure and temperature. Naphthalene is recommended as a reference substance for intercomparisons of investigations in the low vaporpressure region.

Use of the gas saturation method to determine vapour pressure and solubility of antioxidants in polymers

Use of the gas saturation method to determine vapour pressure and solubility of antioxidants in polymers

Human cerebral blood flow measured by two inert gas techniques. Comparison of the Kety-Schmidt method and the intra-arterial injection method.

Two inert gas methods for measurement of tissue blood flow were compared. The two methods are (1) Kety and Schmidt's inert gas saturation method, in which the tissue saturation is followed by detecting the concentration of the tracer in the venous blood leaving the organ and (2) the intraarterial radioactive inert gas injection method where the tissue washout is measured by detecting the residue inside the tissue by an external scintillation detector. Theoretical considerations show a close relation between the two methods when carried to the time of full saturation or desaturation of the tissue or when stopped before full saturation. Experimental studies of cerebral blood flow in nine human subjects using Kr 85 revealed a close correlation between the two methods without any systematic difference between the two sets of data. The Kety-Schmidt outflow detection method is the method of choice for studying over-all tissue perfusion and metabolism. The residue detection method is best suited for measuring flow through circumscribed regions inside an organ and for resolving the flow curve to yield estimates of flow and relative weight of various tissue components.

Measurement of vapor pressure: A gas saturation method

Presents an experiment involving the measurement of vapor pressure using a gas saturation method.