Vapor pressure potassium chloride

In France, Compagnie Europnene du Zirconium (CEZUS) now owned jointly by Pechiney, Eramatome, and Cogema, uses a separation (14) based on the extractive distillation of zirconium—hafnium tetrachlorides in a molten potassium chloride—aluminum trichloride solvent at atmospheric pressure at 350°C. Eor feed, the impure zirconium—hafnium tetrachlorides from the zircon chlorination are first purified by sublimation. The purified tetrachlorides are again sublimed to vapor feed the distillation column containing the solvent salt. Hafnium tetrachloride is recovered in an enriched overhead fraction which is accumulated and reprocessed to pure hafnium tetrachloride. 

The volatilities of both zirconium tetrachloride and hafnium tetrachloride are very similar to each other at normal operating temperatures, and their separation by a simple distillation or fractional distillation operation is not viable. However, when the mixed chloride vapor is contacted with an eutectic molten salt mixture of aluminum chloride and potassium chloride, zirconium chloride is preferentially absorbed. The vapor pressure difference between zirconium and hafnium tetrachlorides is greatly enhanced over the molten... 

ACTIVITY COEFFICIENT. A fractional number which when multiplied by the molar concentration of a substance in solution yields the chemical activity. This term provides an approximation of how much interaction exists between molecules at higher concentrations. Activity coefficients and activities are most commonly obtained from measurements of vapor-pressure lowering, freezing-point depression, boiling-point elevation, solubility, and electromotive force. In certain cases, activity coefficients can be estimated theoretically. As commonly used, activity is a relative quantity having unit value in some chosen standard state. Thus, the standard state of unit activity for water, dty, in aqueous solutions of potassium chloride is pure liquid water at one atmosphere pressure and the given temperature. The standard slate for the activity of a solute like potassium chloride is often so defined as to make the ratio of the activity to the concentration of solute approach unity as Ihe concentration decreases to zero. 

A nonpolar solubilizate such as hexane penetrates deeply into such a micelle, and is held in the nonpolar interior hydrocarbon environment, while a solubilizate such as an alcohol, which has both polar and nonpolar ends, usually penetrates less, with its polar end at or near the polar surface of the micelle. The vapor pressure of hexane in aqueous solution is diminished by the presence of sodium oleate m a manner analogous to that cited above for systems in nonpolar solvents. A 5% aqueous solution of potassium oleate dissolves more than twice the volume of propylene at a given pressure than does pure water. Dnnethylaminoazobenzene, a water-insoluble dye, is solubilized to the extent of 125 mg per liter by a 0.05 M aqueous solution of potassium myristate. Bile salts solubilize fatty acids, and this fact is considered important physiologically. Cetyl pyridinium chloride, a cationic salt, is also a solubilizing agent, and 100 ml of its A/10 solution solubilizes about 1 g of methyl ethyl-butyl either m aqueous solution. 

Deliquescence is a property of substances very soluble in water. When such substances, potassium carbonate or calcium chloride for example, are exposed to the air, the water vapor forms with the substance a small quantity of a saturated solution. This saturated solution has a lower vapor pressure than that of the atmosphere, that is, the water is held by the substance, it does not tend to escape, hence more water vapor is added from the air, and finally the substance is entirely dissolved in this condensed vapor. Common salt or sodium chloride often appears to deliquesce, but the deliquescence is due to the very soluble magnesium and calcium chlorides which are usually mixed with commercial sodium chloride. Sodium nitrate is very soluble in water at the ordinary temperature, but potassium nitrate is only slightly soluble. Hence potassium nitrate, and not sodium nitrate, is used in the manufacture of gunpowder. 

Like its bromine analogue, cyanogen chloride is produced by th< direct chlorination of a saturation solution of potassium cyanide at 0°C. it is a colorless liquid, of 1.22. specific gravity, which l>oils at 15 C. (,59 F.), yielding a volatile irritant vapor 1.98 times heavier than air.. t 20 C. (68 K.) the vapor pressure of cyanogen chloride is 1,000 mm. Hg and its volatility is 3,300 mg. per liter, so that it is more volatile than hydrocyanic acid. 

The activities of Li2ZrCl6, Na2ZrCl6, and K2ZrCl0 in the systems MCl-MaZrClg were recalculated from available vapor pressure data (186). Previously reported calculations (342) for the sodium and potassium chloride systems are now known to be in error. The calculations indicate positive deviations from ideality that decrease with increasing size of the alkali metal cation. Equilibrium constants for the dissociation... 

Metallic potassium and sodium-potassium alloys (NaK) are manufactured by the reaction of high temperature sodium at atmospheric pressure with molten potassium chloride. Early operations of a batch process have been succeeded by a continuous one in which either pure potassium or sodium-potassium alloy of any desired composition can be produced. Molten potassium chloride is introduced into a packed column and brought in contact with ascending sodium vapors in a reaction zone to produce an equilibrium vapor of sodium and potassium. A fractionating column above the reaction zone separates the lighter boiling potassium to any degree of purity desired. The sodium chloride formed is continuously withdrawn from below the reaction zone. 

Pitzer KS (1984) Critical point and vapor pressure of ionic fluids including sodium chloride and potassium chloride. Chem Phys Lett 105 484-489... 

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