Thermodynamic properties of aqueous solutions of the alkali metal chlorides to 250/sup 0/C
Osmotic coefficients of LiCl(aq), KCl(aq), and CsCl(aq) have been determined, at 225 and 250/sup 0/C, by isopiestic comparison with NaCl(aq). Equilibrium molalities ranged up to 8 mol kg/sup -1/. Isothermal osmotic data can be precisely described by the ion interaction model of Pitzer. The osmotic, and activity, coefficients continue to decrease with increasing temperature with LiCl(aq) retaining a measure of individuality when compared to the other alkali metal chlorides. Our present results have been compared and combined with previously reported thermodynamic data (isopiestic and vapor pressure measurements, electrochemical cell potentials, freezing temperature determinations, enthalpies of solution and dilution, and heat capacities) within the framework of the ion interaction model. The resulting set of equations provides a thermodynamic description, essentially within the accuracy of the reported experimental results, of LiCl(aq), KCl(aq), and CsCl(aq) as a function of temperature (from 0 to 250 /sup 0/C) and molality (up to about 6 mol kg/sup -1/). The ion interaction parameter ..beta../sup (0)/ was in the order LiCl > NaCl > KCl > CsCl at all temperatures. The same trend was observed for the excess thermodynamic properties phi, ..gamma.., and /sup phi/L. Contributions of the short-range interactions to the activity coefficient (ln ..gamma.. - f/sup ..gamma../) are shown to be linearly related to the reciprocal radius of the cation. Excess free energy data for the alkali metal chlorides to 250/sup 0/C can be modeled surprisingly well with a single parameter--the hard-core diameter--using the theoretical form of the ion interaction model.
- Research Organization:
- Oak Ridge National Laboratory, TN
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5522017
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 87:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CESIUM CHLORIDES
THERMODYNAMIC PROPERTIES
LITHIUM CHLORIDES
POTASSIUM CHLORIDES
SODIUM CHLORIDES
AQUEOUS SOLUTIONS
CATIONS
EQUILIBRIUM
FREE ENERGY
HIGH TEMPERATURE
ISOTHERMAL PROCESSES
MEDIUM TEMPERATURE
OSMOSIS
TEMPERATURE DEPENDENCE
ALKALI METAL COMPOUNDS
CESIUM COMPOUNDS
CHARGED PARTICLES
CHLORIDES
CHLORINE COMPOUNDS
DIFFUSION
DISPERSIONS
ENERGY
HALIDES
HALOGEN COMPOUNDS
IONS
LITHIUM COMPOUNDS
LITHIUM HALIDES
MIXTURES
PHYSICAL PROPERTIES
POTASSIUM COMPOUNDS
SODIUM COMPOUNDS
SOLUTIONS
400201* - Chemical & Physicochemical Properties