Correction of Holloway's (1977) adaptation of the modified Redlich-Kwong equation of state for calculation of the fugacities of molecular species in supercritical fluids of geologic interest

Flowers, George C.

doi:10.1007/bf00372333

Cited by 114 publications

(37 citation statements)

References 4 publications

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“…For simplicity, the vapor phase has been assumed to be a perfect gas, though at elevated p and T it could equally well be represented more accurately by using, for example, the modified Redlich-Kwong equation of state [Flowers, 1979]. The heat content of the liquid and solid phases is much larger than that of the vapor, so exsolution takes place at nearly constant temperature.…”

Section: Mvpomentioning

confidence: 99%

Seismic triggering by rectified diffusion in geothermal systems

Sturtevant¹,

Kanamori²,

Brodsky³

1996

J. Geophys. Res.

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Abstract.Widespread seismicity was triggered by the June 28, 1992, Landers California, earthquake at a rate which was maximum immediately after passage of the exciting seismic waves. Rectified diffusion of vapor from hydrothermal liquids and magma into bubbles oscillating in an earthquake can increase the local pore pressure to seismically significant levels within the duration of the earthquake. In a hydrothermal system modeled as a two-component H

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Section: Mvpomentioning

confidence: 99%

Seismic triggering by rectified diffusion in geothermal systems

Sturtevant¹,

Kanamori²,

Brodsky³

1996

J. Geophys. Res.

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“…We have calculated f~, 0 (P,T), the fugacity of pure HzO at T and P, from the modified Redlich-Kwong equation of state for H 2 0 (Holloway 1977 ;Flowers 1979). To use equation (20), we must estimate the partial molar volume of molecular water in the melt.…”

Section: Melt-vapor Equilibriummentioning

confidence: 99%

A Thermodynamic Model for Hydrous Silicate Melts

Silver¹,

Stolper²

1985

The Journal of Geology

122

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A simple thermodynamic model describing hydrous silicate melts has been applied to the systems albite-, diopside-, and silica-H 2 0. The model is based on the assumption of ideal mixing of hydroxyl groups, H 2 0 111olecules, and oxygens in the melt. Calculated and experimentally determined freezing-point depressions and H 2 0 solubilities for these systems are in agreement over substantial pressure and temperature intervals. The success of this model in accounting for observed phase equilibria of hydrous systems and its consistency with spectroscopic measurements of the concentrations of H-bearing species in glasses suggests that it accurately represents the interaction between H 2 0 and silicate melts at a molecular level.

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“…Flowers (1979) pointed out that the equation used by Holloway (1976) to calculate the fugacity coefficients did not obey the Gibbs-Duhem relation and was in error. The corrected EOS predicts considerable more ideal fugacity coefficients than the uncorrected EOS.…”

Section: Holloway (1976) Holloway (1981)mentioning

confidence: 99%

Equations of State for Complex Fluids

Gottschalk¹

2007

Reviews in Mineralogy and Geochemistry

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INTRODUCTIONCompositions of coexisting fluids at elevated pressure-temperature conditions can be calculated by applying thermodynamics as in any other chemical equilibrium. This calculation requires the evaluation of the thermodynamic properties of the phase components i at the respective pressure P, temperature T, and the individual abundances x i , i.e. composition. In comparison with solids, fluids normally have distinct PVT-behaviors. Furthermore, because of their disordered state and the relatively weak bonding between molecules, fluid species mix much more easily than solid-phase components. The evaluation of the thermodynamic properties of fluids requires, therefore, special treatment and procedures that differ significantly from those used for solids. For fluids, this treatment includes a distinct and different standard state than for solids and a special description of the volume V as a function of P, T (or P as a function of V and T) and x i , i.e. an equation of state (EOS). PRINCIPLESFor geological systems, which are usually defined by the variables P and T, the Gibbs free energy G is the function of choice to describe equilibria. At constant P and T the chemical equilibrium condition is defined by (the Table 1 lists the symbols used):The partial derivative of G with respect to P is the volume VTherefore, the pressure-dependence of G is obtained by integration of Equation (2) with boundaries from the reference pressure P r , i.e. ambient pressure of 0.1 MPa, to the required P G (P,T ) = G (P r ,T ) + VdP For solids using the standard state of a pure phase component at reference conditions P r and T r , (i.e. 0.1 MPa, 298 K) integration over P leads to,where h i o and s i o are the molar enthalpy and entropy at P r and T, v i o the molar volume as a function of P at T of the pure phase component i, and a i is its activity, which also incorporates in this case any volume effects of mixing.However, for fluids the standard state is defined differently, and Equation (5) is not used in this form. The principal thermodynamic equations are rearranged in such a way that, at the standard state, the properties of a pure fluid are taken as if this fluid would behave like an ideal gas. For fluids, the standard state is, therefore, that of a hypothetical ideal gas at P r at any required temperature T. The use of this standard state leads to the following expression,in which the asterisk denotes the hypothetical ideal gas standard state properties. Details of the derivation of Equation (6), and Equation (11) in the following, can be found for example in Beattie (1955) or in Appendix A.The integral term in Equation (6) provides the definition of the fugacity coefficientThus Equation (6) can be written asand with definition of the fugacity f i m 1 The term phase component is used as a synonym for a endmember of a solution, i.e. for fluids specific species or molecules, whereas the term component is used in the classic thermodynamical sense.2 The lower integration boundary is strictly 0 MPa and not just some low pre...

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Correction of Holloway's (1977) adaptation of the modified Redlich-Kwong equation of state for calculation of the fugacities of molecular species in supercritical fluids of geologic interest

Cited by 114 publications

References 4 publications

Seismic triggering by rectified diffusion in geothermal systems

Seismic triggering by rectified diffusion in geothermal systems

A Thermodynamic Model for Hydrous Silicate Melts

Equations of State for Complex Fluids

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