Diffusion of some Hydrocarbons in Air: a Regularity in the Diffusion Coefficients of a Homologous Series

Abstract

Diffusion coefficients in air at 298.2 "K and I atm pressure are reported for ethane, ethene, ethyne, cyclopropane, propene, propadiene, propyne, butane, I-butene, 2-methylpropene, cis-2-butene, trans-2-butene, 1,3-butadiene, I-butyne, 2-methylbutane, 2,2-dimethylpropane, cyclopentane, and 1-pentene.A linear relationship, valid for alkanes and alkenes, has been found between the diffusion coefficient and the reduced molecular weight of the members of a homologous series and air.Diffusion coefficients calculated by ten prediction equations were generally lower than those observed.Les coefficients de diffusion dans l'air a 298.2 "K et sous une pression de une atmosphere sont rapportes pour l'ethane, Pethene, l'ethyne, le cyclopropane, le propkne, le propadiene, le propyne, le butane, le butene-I, le methyl-2 propene, le butkne-2 cis, le butine-2 trans, le butadiine-1,3, le butyne-I, le methyl-2 butane, le dimethyl-2,2 propane, le cyclopentane et le pentine-I. Une relation lineaire, valable pour les alcanes et les alcenes, existe entre le coefficient de diffusion et la masse mol6culaire reduite des membres d'une sirie homologue et l'air.Les coefficients de diffusion, calculCs a partir de dix equations de prediction, sont generalement plus bas que ceux observes.

Removal of low concentration contaminant species using photocatalysis: Elimination of ethene to sub-ppm levels with and without water vapor present

“…Vesborg et al [17] even found for methanol photooxidation on TiO 2 that photodesorption is more pronounced at longer wavelengths of light, further increasing k À 1 . A diffusion constant of D ¼ 0:17 cm 2 s À1 compares well to literature values of 0.1655 cm 2 s À1 for ethene in air [18]. Data up to a gas velocity of 200 m h À1 are available, but the model fits are extrapolated to higher velocities where the model ensures that the correct limit in output concentration is reached -never surpassing the input concentration.…”

“…Ethene emission as a function of ethene concentration in the surrounding air, evaluated through Eq. (18). Km is the concentration of half maximum response, and p max is the maximum production rate at infinite input concentration CB.…”

Description of the response of a fiber optic velocity sensor applied to capillary gas chromatography

“…Fitting the data with Eqs. (7) and (8), taking ˇ= 1.61 cm −1 , one calculates a diffusion coefficient of 0.030 cm 2 /s for pentane in helium, while the value reported in the literature is 0.092 cm 2 /s [17]. The difference may be explained by the approximation of the vapor zone by a Gaussian, which actually is far from being the case, as shown in the inset of Fig.…”

Evaporation with the formation of chains of liquid bridges

“…• C. Data for the vapour-air diffusion coefficient D were obtained from various references (Cummings & Ubbelohde 1953;Altshuller & Cohen 1960;Lugg 1968;Elliott & Watts 1972;Beverley, Clint & Fletcher 1999) and extrapolated to 22 ± 1…”