Molecular Association in Alkali Halide Vapors [Thesis]
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Molecular association equilibria in alkali halide vapors were studied by measuring the temperature dependence of the molecular weights of gaseous sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium iodide, rubidium chloride, and cesium chloride. The molecular weights were determined by measurement of the absolute pressure exerted by a known weight of completely vaporized salt contained in an isothermal fused silica bulb of known volume. The pressure sensing element consisted of a fused silica U-tube manometer containing molten gold, and pressures were determined by measuring the argon pressure necessary to balance the gold manometer. The apparatus was used in the temperature range of 1175 to 1430° K and pressures of from 10 to 40 mm were measured with a precision of ± 0.05 mm. The temperature dependence of the equilibrium constants for the reaction (MX)2 ⇌ 2MX yielded dissociation energies (evaluated at 1300° K) ranging from 48.0 kcal mole-1 for sodium chloride to 34.7 kcal for cesium chloride. The entropies of dissociation were found to fall within a small range, varying from 28.3 e.u. for sodium chloride to 25.0 for potassium iodide. A statistical calculation of the entropy changes based on an ionic model was found to agree well with the experimental values. It is shown that these systems may be adequately described with an electrostatic model, although closer attention should be paid to the nature of polarization interactions.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- US Atomic Energy Commission (AEC)
- DOE Contract Number:
- W-7405-ENG-26
- NSA Number:
- NSA-14-015628
- OSTI ID:
- 4156066
- Report Number(s):
- ORNL--2933
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALKALI METALS
ARGON
BEHAVIOR
CESIUM CHLORIDES
GASES
GOLD
HALIDES
MANOMETERS
MEASURED VALUES
MOLECULES
POTASSIUM CHLORIDES
POTASSIUM IODIDES
PRESSURE
RUBIDIUM CHLORIDES
SODIUM BROMIDES
SODIUM CHLORIDES
SODIUM IODIDES
THERMODYNAMICS
VAPORS
WEIGHT