Show simple item record Su, JT Duncan, PB Momaya, A Jutila, A Needham, D
dc.coverage.spatial United States 2011-04-15T16:46:50Z 2010-01-28
dc.identifier.citation J Chem Phys, 2010, 132 (4), pp. 044506 - ?
dc.description.abstract While the Stokes-Einstein (SE) equation predicts that the diffusion coefficient of a solute will be inversely proportional to the viscosity of the solvent, this relation is commonly known to fail for solutes, which are the same size or smaller than the solvent. Multiple researchers have reported that for small solutes, the diffusion coefficient is inversely proportional to the viscosity to a fractional power, and that solutes actually diffuse faster than SE predicts. For other solvent systems, attractive solute-solvent interactions, such as hydrogen bonding, are known to retard the diffusion of a solute. Some researchers have interpreted the slower diffusion due to hydrogen bonding as resulting from the effective diffusion of a larger complex of a solute and solvent molecules. We have developed and used a novel micropipette technique, which can form and hold a single microdroplet of water while it dissolves in a diffusion controlled environment into the solvent. This method has been used to examine the diffusion of water in both n-alkanes and n-alcohols. It was found that the polar solute water, diffusing in a solvent with which it cannot hydrogen bond, closely resembles small nonpolar solutes such as xenon and krypton diffusing in n-alkanes, with diffusion coefficients ranging from 12.5x10(-5) cm(2)/s for water in n-pentane to 1.15x10(-5) cm(2)/s for water in hexadecane. Diffusion coefficients were found to be inversely proportional to viscosity to a fractional power, and diffusion coefficients were faster than SE predicts. For water diffusing in a solvent (n-alcohols) with which it can hydrogen bond, diffusion coefficient values ranged from 1.75x10(-5) cm(2)/s in n-methanol to 0.364x10(-5) cm(2)/s in n-octanol, and diffusion was slower than an alkane of corresponding viscosity. We find no evidence for solute-solvent complex diffusion. Rather, it is possible that the small solute water may be retarded by relatively longer residence times (compared to non-H-bonding solvents) as it moves through the liquid.
dc.format.extent 044506 - ?
dc.language eng
dc.language.iso en_US en_US
dc.relation.ispartof J Chem Phys
dc.relation.isversionof 10.1063/1.3298857
dc.subject Alcohols
dc.subject Alkanes
dc.subject Diffusion
dc.subject Hydrogen Bonding
dc.subject Microchemistry
dc.subject Solvents
dc.subject Water
dc.title The effect of hydrogen bonding on the diffusion of water in n-alkanes and n-alcohols measured with a novel single microdroplet method.
dc.type Journal Article
dc.description.version Version of Record en_US 2010-1-28 en_US
duke.description.endpage 44506 en_US
duke.description.issue 4 en_US
duke.description.startpage 44506 en_US
duke.description.volume 132 en_US
dc.relation.journal Journal of Chemical Physics en_US
pubs.issue 4
pubs.organisational-group /Duke
pubs.organisational-group /Duke/Pratt School of Engineering
pubs.organisational-group /Duke/Pratt School of Engineering/Mechanical Engineering and Materials Science
pubs.organisational-group /Duke/School of Medicine
pubs.organisational-group /Duke/School of Medicine/Institutes and Centers
pubs.organisational-group /Duke/School of Medicine/Institutes and Centers/Duke Cancer Institute
pubs.publication-status Published
pubs.volume 132
dc.identifier.eissn 1089-7690

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