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Title: Structure and dynamics of liquid ethanol

Abstract

Molecular dynamics simulations of liquid ethanol at four thermodynamic states ranging from T = 173 K to T = 348 K were carried out using the transferable OPLS potential model of W.L. Jorgensen. Both static and dynamic properties are analyzed. The resulting properties show an overall agreement with available experimental data. Special attention is paid to the hydrogen bonds and to their influence on the molecular behavior. Results for liquid ethanol are compared with those for methanol in earlier computer simulation studies. 30 refs., 13 figs., 5 tabs.

Authors:
;  [1];  [2]
  1. Universitat de Barcelona (Spain)
  2. Universitat Politecnica de Catalunya, Barcelona (Spain)
Publication Date:
OSTI Identifier:
501907
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical; Journal Volume: 101; Journal Issue: 1; Other Information: PBD: 2 Jan 1997
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; 66 PHYSICS; ETHANOL; THERMODYNAMICS; THERMODYNAMIC PROPERTIES; MOLECULAR STRUCTURE; COMPUTERIZED SIMULATION; MOLECULAR MODELS; CHEMICAL BONDS

Citation Formats

Saiz, L., Padro, J.A., and Guardia, E. Structure and dynamics of liquid ethanol. United States: N. p., 1997. Web. doi:10.1021/jp961786j.
Saiz, L., Padro, J.A., & Guardia, E. Structure and dynamics of liquid ethanol. United States. doi:10.1021/jp961786j.
Saiz, L., Padro, J.A., and Guardia, E. 1997. "Structure and dynamics of liquid ethanol". United States. doi:10.1021/jp961786j.
@article{osti_501907,
title = {Structure and dynamics of liquid ethanol},
author = {Saiz, L. and Padro, J.A. and Guardia, E.},
abstractNote = {Molecular dynamics simulations of liquid ethanol at four thermodynamic states ranging from T = 173 K to T = 348 K were carried out using the transferable OPLS potential model of W.L. Jorgensen. Both static and dynamic properties are analyzed. The resulting properties show an overall agreement with available experimental data. Special attention is paid to the hydrogen bonds and to their influence on the molecular behavior. Results for liquid ethanol are compared with those for methanol in earlier computer simulation studies. 30 refs., 13 figs., 5 tabs.},
doi = {10.1021/jp961786j},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
number = 1,
volume = 101,
place = {United States},
year = 1997,
month = 1
}
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  • No abstract prepared.
  • The vapor-liquid equilibria for the five alkanol + alkane binary systems methanol + hexane, methanol + heptane, ethanol + hexane, ethanol + heptane, and ethanol + octane were measured by a flow-type apparatus at 298.15 K. The values of the activity coefficient are greater than unity. The experimental results obtained were correlated by several equations for activity coefficients, and these correlations are compared.
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  • We investigated by means of molecular dynamics simulations the properties (structure, thermodynamics, ion transport, and dynamics) of the protic ionic liquid N,N-diethyl-N-methyl-ammonium triflate (dema:Tfl) and of selected aqueous mixtures of dema:Tfl. This ionic liquid, a good candidate for a water-free proton exchange membrane, is shown to exhibit high ion mobility and conductivity. For bulk melts in the temperature range of 303-453K, both liquid densities and enthalpies of vaporization are found to decrease roughly linearly with increasing temperature. The radial distribution functions reveal a significant long-range structural correlation. The ammonium cations [dema]+ are found to diffuse slightly faster than the triflatemore » anions [Tfl]-, and both types of ions exhibit enhanced mobility at higher temperatures, leading to higher ionic conductivity of these ionic liquids. Analysis of the dynamics of ion pairing clearly points to the existence of long-lived contact ion pairs in this ionic liquid. We also examined the effects of water on the ionic properties of dema:Tfl-water mixtures. From the structural analysis it was found that water molecules tend to replace counter ions in the coordination shell and hydrogen bond to both ions, thus weakening their mutual association. As water concentration increases, water molecules start to connect with each other and eventually form a large network that percolates through the system. It is also found that water has a strong influence on the ion dynamics in the mixtures. As the concentration of water increases, both translational and rotational motion of [dema]+ and [Tfl]- are significantly enhanced. As a result, higher ionic conductivity is observed with increased hydration level. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.« less