OSMOTIC AND ACTIVITY COEFFICIENTS OF SOME AQUEOUS RARE-EARTH CHLORIDE SOLUTIONS AT 25 C
The least square equations obtained for the osmotic coefficient as a function of molality for erbium and yttrium chloride solutions resulted in a mean deviation of 0.0019 and 0.0024 in the osmotic coefficient, respectively, for the two solutions. These deviations at a median osmotic coefficient are 0.08% for erbium chloride and 0.10% for yttrium chloride. Of course, the percent error in the osmotic coefficient is larger for the most dilute solutions and lower for the saturated solutions. The corresponding error in the activity coefficient was determined to be about 0.0010 in the log gamma /sub plus or minus /, while the activity coefficients were in error by 0.008 for gamma /sub plus or minus / = 0.3261 in the dilute solution range or by 0.020 for gamma /sub plus or minus / = 9.760 in the most concentrated solutions of erbium chloride. All deviations in the activity coefficient gave an almost uniform mean deviation of 0.23%. These deviations in the activity coefficient correspond with those expected from the experimental procedure of this type of research. The errors concurred are: the error in analysis of each solution was of the order of 0.05% for molalities greater than one and from 0.10 to 0.15% for molalities less than one; and the reliability of the reference osmotic coefficient data is about 0.0010 in the osmotic coefficient. Since the molalities of two solutions must be known for the calculation of the rare-earth osmotic coefficient, a mean deviation of 0.0020 in its osmotic coefficient determined in this research is within the experimental precision of the isopiestic method. The osmotic and activity coefficients determined by Spedding and Saeger and by this research, for the rare-earth chlorides, show a marked increase across the series, particularly at high concentrations. For example, the activity coefficients at 3.4 molal are; La(3.303) < Nd(3.822) < Sm(4.087) < Gd(4.836) < Dy(5.539) < Er(6.372) < Y(6.504). The osmotic and activity coefficients of yttrium chloride behave like those of the heavy rareearth chlorides. The high activity coefficient of concentrated rare-earth chloride solutions strongly indicates that complete ionization of the electrolyte is far from being the case. The formation of complexes and polymerization of the electrolyte along with an increase in hydration, which decreases the water activity, all partly account for a high activity coefficient for the electrolyte. (auth)
- Research Organization:
- Ames Lab., Ames, Iowa
- DOE Contract Number:
- W-7405-ENG-82
- NSA Number:
- NSA-18-013722
- OSTI ID:
- 4088261
- Report Number(s):
- IS-770
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHEMISTRY
CHLORIDES
COMPLEXES
DECOMPOSITION
DIAGRAMS
DYSPROSIUM CHLORIDES
ELECTROLYTES
EQUATIONS
ERBIUM CHLORIDES
ERRORS
GADOLINIUM CHLORIDES
IONS
LANTHANUM CHLORIDES
MEASURED VALUES
MEMBRANES
MOLECULES
NEODYMIUM CHLORIDES
NUMERICALS
OSMOSIS
PRESSURE
QUANTITY RATIO
RARE EARTHS
REACTION KINETICS
SAMARIUM CHLORIDES
SOLUBILITY
SOLUTIONS
SOLVENTS
STATISTICS
TABLES
THERMODYNAMICS
VARIATIONS
WATER
YTTRIUM CHLORIDES