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Title: Thermodynamics of clathrate hydrate at low and high pressures with application to the outer solar system

Abstract

The thermodynamic stability of clathrate hydrate is calculated under a wide range of temperature and pressure conditions applicable to solar system problems, using a statistical mechanical theory developed by van der Waals an Platteeuw (1959) and existing experimental data on properties of clathrate hydrates and their components. At low pressure, dissociation pressures and partition functions (Langmuir constants) for CO clathrate (hydrate) have been predicted, using the properties of clathrate containing, as guests, molecules similar to CO. The comparable or higher propensity of CO to incorporate in clathrate relative to N/sub 2/ is used to argue for high CO-to-N/sub 2/ ratios in primordial Titan in N/sub 2/ was accreted as clathrate. The relative incorporation of noble gases in clathrate from a solar composition gas at low temperatures is calculated and applied to the case of giant-planet atmospheres and icy satellites. It is argued that nonsolar but well-constrained noble gas abundances will be measured by Galileo in the Jovian atmosphere if the observed carbon enhancement is due to bombardment of the atmosphere by clathrate- bearing planetesimals sometime after planetary formation. The noble gas abundances in Titan's atmosphere are also predicted under the hypothesis that much of the stellite's methane accreted a clathrate.more » Double occupancy of clathrate cages by H/sub 2/ and CH/sub 4/ in contact with a solar composition gas is examined, and it is concluded that potentially important amounts of H/sub 2/ may have incorporated in satellites as clathrate. The kinetics of clathrate formation is also examined, and it is suggested that, under thermodynamically appropriate conditions, essentially complete clathration of water ice could have occurred in high-pressure nebulae around giant planets but probably not in the outer solar nebula; comets probably did not aggregate as clathrate.« less

Authors:
;
Publication Date:
Research Org.:
Division of Geological and Planetary Sciences, California Institute of Technology
OSTI Identifier:
5363872
Resource Type:
Journal Article
Journal Name:
Astrophys. J., Suppl. Ser.; (United States)
Additional Journal Information:
Journal Volume: 58:3
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CLATHRATES; SYNTHESIS; HYDRATES; PLANETARY ATMOSPHERES; COSMOCHEMISTRY; CHEMICAL COMPOSITION; PRESSURE DEPENDENCE; STATISTICAL MECHANICS; TEMPERATURE DEPENDENCE; ATMOSPHERES; CHEMISTRY; MECHANICS; 640107* - Astrophysics & Cosmology- Planetary Phenomena

Citation Formats

Lunine, J I, and Stevenson, D J. Thermodynamics of clathrate hydrate at low and high pressures with application to the outer solar system. United States: N. p., 1985. Web. doi:10.1086/191050.
Lunine, J I, & Stevenson, D J. Thermodynamics of clathrate hydrate at low and high pressures with application to the outer solar system. United States. doi:10.1086/191050.
Lunine, J I, and Stevenson, D J. Mon . "Thermodynamics of clathrate hydrate at low and high pressures with application to the outer solar system". United States. doi:10.1086/191050.
@article{osti_5363872,
title = {Thermodynamics of clathrate hydrate at low and high pressures with application to the outer solar system},
author = {Lunine, J I and Stevenson, D J},
abstractNote = {The thermodynamic stability of clathrate hydrate is calculated under a wide range of temperature and pressure conditions applicable to solar system problems, using a statistical mechanical theory developed by van der Waals an Platteeuw (1959) and existing experimental data on properties of clathrate hydrates and their components. At low pressure, dissociation pressures and partition functions (Langmuir constants) for CO clathrate (hydrate) have been predicted, using the properties of clathrate containing, as guests, molecules similar to CO. The comparable or higher propensity of CO to incorporate in clathrate relative to N/sub 2/ is used to argue for high CO-to-N/sub 2/ ratios in primordial Titan in N/sub 2/ was accreted as clathrate. The relative incorporation of noble gases in clathrate from a solar composition gas at low temperatures is calculated and applied to the case of giant-planet atmospheres and icy satellites. It is argued that nonsolar but well-constrained noble gas abundances will be measured by Galileo in the Jovian atmosphere if the observed carbon enhancement is due to bombardment of the atmosphere by clathrate- bearing planetesimals sometime after planetary formation. The noble gas abundances in Titan's atmosphere are also predicted under the hypothesis that much of the stellite's methane accreted a clathrate. Double occupancy of clathrate cages by H/sub 2/ and CH/sub 4/ in contact with a solar composition gas is examined, and it is concluded that potentially important amounts of H/sub 2/ may have incorporated in satellites as clathrate. The kinetics of clathrate formation is also examined, and it is suggested that, under thermodynamically appropriate conditions, essentially complete clathration of water ice could have occurred in high-pressure nebulae around giant planets but probably not in the outer solar nebula; comets probably did not aggregate as clathrate.},
doi = {10.1086/191050},
journal = {Astrophys. J., Suppl. Ser.; (United States)},
number = ,
volume = 58:3,
place = {United States},
year = {1985},
month = {7}
}