Geology topics

Kenneth S. Pitzer

Publications and source records attributed to Kenneth S. Pitzer.

7 recordsLinked to original sources

USGS2002

Vapor-liquid phase equilibria of potassium chloride-water mixtures: Equation-of-state representation for KCl-H2O and NaCl-H2O

Measurements of isothermal vapor-liquid compositions for KCl-H2O as a function of pressure are reported. An equation of state, which was originally proposed by Pitzer and was improved and used by Tanger and Pitzer to fit the vapor-liquid coexistence surface for NaCl-H2O, has been used for representation of the KCl-H2O system from 300 to 410??C. Improved parameters are also reported for NaCl-H2O from 300 to 500??C. ?? 1990 American Chemical Society.

Journal of Physical Chemistry↗

USGS1992

Phase relations in the system NaCl-KCl-H2O: IV. Differential thermal analysis of the sylvite liquidus in the KCl-H2O binary, the liquidus in the NaCl-KCl-H2O ternary, and the solidus in the NaCl-KCl binary to 2 kb pressure, and a summary of experimental data for thermodynamic-PTX analysis of solid-liquid equilibria at elevated P-T conditions

The sylvite liquidus in the binary system KCl-H2O and the liquidus in the ternary system NaCl-KCl-H2O were determined by using isobaric differential thermal analysis (DTA) cooling scans at pressures up to 2 kbars. Sylvite solubilities along the three-phase curve in the binary system KCl-H2O were obtained by the intersection of sylvite-liquidus isopleths with the three-phase curve in a P-T plot. These solubility data can be represented by the equation Wt.% KCl (??0.2) = 12.19 + 0.1557T - 5.4071 ?? 10-5 T2, where 400 ??? T ??? 770??C. These data are consistent with previous experimental observations. The solidus in the binary system NaCl-KCl was determined by using isobaric DTA heating scans at pressures up to 2 kbars. Using these liquidus and solidus data and other published information, a thermodynamic-PTX analysis of solid-liquid equilibria at high pressures and temperatures for the ternary system has been performed and is presented in an accompanying paper (Part V of this series). However, all experimental liquidus, solidus, and solvus data used in this analysis are summarized in this report (Part IV) and they are compared with the calculated values based on the analysis. ?? 1992.

Geochimica et Cosmochimica Acta↗

USGS1992

Phase relations in the system NaCl-KCl-H2O: V. Thermodynamic-PTX analysis of solid-liquid equilibria at high temperatures and pressures

The Gibbs energies of mixing for NaCl-KCl binary solids and liquids and solid-saturated NaCl-KCl-H 2 O ternary liquids were modeled using asymmetric Margules treatments. The coefficients of the expressions were calibrated using an extensive array of binary solvus and solidus data, and both binary and ternary liquidus data. Over the PTX range considered, the system exhibits complete liquid miscibility among all three components and extensive solid solution along the anhydrous binary. Solid-liquid and solid-solid phase equilibria were calculated by using the resulting equations and invoking the equality of chemical potentials of NaCl and KCl between appropriate phases at equilibrium. The equations reproduce the ternary liquidus and predict activity coefficients for NaCl and KCl components in the aqueous liquid under solid-saturation conditions between 673 and 1200 K from vapor saturation up to 5 kbar. In the NaCl-KCl anhydrous binary system, the equations describe phase equilibria and predict activity coefficients of the salt components for all stable compositions of solid and liquid phases between room temperature and 1200 K and from 1 bar to 5 kbar.

Geochimica et Cosmochimica Acta↗

USGS1989

Liquid-vapor relations for the system NaCl-H2O: Summary of the P-T- x surface from 300° to 500°C

Experimental data on the vapor-liquid equilibrium relations for the system NaCl-H 2 O were compiled and compared in order to provide an improved estimate of the P-T-x surface between 300 ° to 500 ° C, a range for which the system changes from subcritical to critical behavior. Data for the three-phase curve (halite + liquid + vapor) and the NaCl-H 2 O critical curve were evaluated, and the best fits for these extrema then were used to guide selection of best fit for isothermal plots for the vapor-liquid region in-between. Smoothing was carried out in an iterative procedure by replotting the best-fit data as isobars and then as isopleths, until an internally consistent set of data was obtained. The results are presented in table form that will have application to theoretical modelling and to the understanding of two-phase behavior in saline geothermal systems.

American Journal of Science↗

USGS1987

Critical behavior of dilute NaCl in H2O

The compositions of the saturated vapor and liquid phases are measured for the system NaCl-H 2 O at 380°C, which is close to the critical point of pure water. The shape of the phase equilibrium curve is classical, which confirms a conclusion reached earlier on the basis of less accurate data. This implies that the long-range forces introduced by the NaCl suppress the non-classical effects present in pure H 2 O. An empirical equation of a classical type fits these data.

Chemical Physics Letters↗

USGS1986

The system NaCl-H 2 O: relations of vapor-liquid near the critical temperature of water and of vapor-liquid-halite from 300° to 500°C

Vapor-liquid relations ( P - T - x ) for the system NaCl-H 2 O were determined experimentally at temperatures spanning the critical temperature of water ( T c ), the lowest temperature in the system at which critical behavior occurs. In addition, vapor-liquid-halite P - T - x (vapor) relations were determined from 300° to 500°C. Results show that at 373.0°C, immediately below T c , the vapor side of the isothermal vaporliquid P-x boundary has a shape quite different from that previously conceived. The NaCl content of the vapor increases with pressure in a smooth manner from the pressure of the three-phase assemblage (135 bars, 0.0029% NaCl), to a pressure just below that of the vapor pressure of pure water (0.012% NaCl at 184 bars). Above this pressure the boundary abruptly reverses and projects asymptotically to 0% NaCl in a beak-like shape at 218 bars, the vapor pressure of pure water. At 375.5°, slightly above T c , the asymptote disappears, and is replaced by a rounded nose. At progressively higher temperatures, the nose disappears and by 380°C the familiar symmetrical bell-shaped curve predominates with the critical point defined by the top of the bell. The P - T curve of the three-phase assemblage determined in the present study is in agreement with previous workers. The NaCl content of the three-phase vapor, however, is much higher than some literature values at temperatures above 410°C.

Geochimica et Cosmochimica Acta↗

USGS1985

Phase relations and adiabats in boiling seafloor geothermal systems

Observations of large salinity variations and vent temperatures in the range of 380–400°C suggest that boiling or two-phase separation may be occurring in some seafloor geothermal systems. Consideration of flow rates and the relatively small differences in density between vapors and liquids at the supercritical pressures at depth in these systems suggests that boiling is occurring under closed-system conditions. Salinity and temperature of boiling vents can be used to estimate the pressure-temperature point in the subsurface at which liquid seawater first reached the two-phase boundary. Data are reviewed to construct phase diagrams of coexisting brines and vapors in the two-phase region at pressures corresponding to those of the seafloor geothermal systems. A method is developed for calculating the enthalpy and entropy of the coexisting mixtures, and results are used to construct adiabats from the seafloor to the P-T two-phase boundary. Results for seafloor vents discharging at 2300 m below sea level indicate that a 385°C vent is composed of a brine (7% NaCl equivalent) in equilibrium with a vapor (0.1% NaCl). Brine constitutes 45% by weight of the mixture, and the fluid first boiled at approximately 1 km below the seafloor at 415°C, 330 bar. A 400°C vent is primarily vapor (88 wt.%, 0.044% NaCl) with a small amount of brine (26% NaCl) and first boiled at 2.9 km below the seafloor at 500°C, 520 bar. These results show that adiabatic decompression in the two-phase region results in dramatic cooling of the fluid mixture when there is a large fraction of vapor.

Earth and Planetary Science Letters↗