Potassium compounds fluoride

Thermodynamic data show that the stabilities of the caesium chloride-metal chloride complexes are greater than the conesponding sodium and potassium compounds, and tire fluorides form complexes more readily tlrair the chlorides, in the solid state. It would seem that tire stabilities of these compounds would transfer into tire liquid state. In fact, it has been possible to account for the heats of formation of molten salt mixtures by the assumption that molten complex salts contain complex as well as simple anions, so tlrat tire heat of formation of the liquid mixtures is tire mole fraction weighted product of the pure components and the complex. For example, in the CsCl-ZrCU system the heat of formation is given on each side of tire complex compound composition, the mole fraction of the compound... 

Examples of the Michael-type addition of carbanions, derived from activated methylene compounds, with electron-deficient alkenes under phase-transfer catalytic conditions have been reported [e.g. 1-17] (Table 6.16). Although the basic conditions are normally provided by sodium hydroxide or potassium carbonate, fluoride and cyanide salts have also been used [e.g. 1, 12-14]. Soliddiquid two-phase systems, with or without added organic solvent [e.g. 15-18] and polymer-supported catalysts [11] have been employed, as well as normal liquiddiquid conditions. The micellar ammonium catalysts have also been used, e.g. for the condensation of p-dicarbonyl compounds with but-3-en-2-one [19], and they are reported to be superior to tetra-n-butylammonium bromide at low base concentrations. 

This structure type, that has been attributed to the fluorides KNbFa and KTaFs by Bode and Dohren [39, 40), is restricted in the case of potassium compounds KMeFe to the same transition elements Me + = Nb, Ta, Mo, W, Re (129), the sodium compounds NaMeFe of which adapt the NaSbFs structure. But as all AgMeFe-compounds 187) hitherto known seem to crystallize in the KNbFe-structure, this type is somewhat wider spread. 

Ternary fluorides of this formula type are restricted to two-valenced cations Me2+, stable almost exclusively in the first transition series only. A number of potassium compounds are known for a long time. During the last years investigations on these compounds were intensified because of their interesting magnetic properties (221) and they were also extended to ternary fluorides AMeFa containing A-ions other than potassium. 

This compound is considered to be the electrolyte which on decomposition forms the two gases and a double potassium platinum fluoride which is deposited as a black mud. This hypothesis has been devised to explain why the initial stage of the electrolysis is irregular and jerky, and only after the lapse of an hour, when the substances in soln. are in sufficient quantities to make the passage of the current regular, is the evolution of fluorine regular. 0. Ruff 1 has shown that ammonium fluoride can be used in place of the potassium salt. 

In 1869, C. W. Blomstrand11 attempted to explain the molecular structure of these compounds by assuming the halogen to be bivalent. This would make potassium acid fluoride K—F—F—H. It is considered more probable that fluorine is uni-, ter-, quadri-, or septa-valent, in harmony with the corresponding variable valency of the other halogens. This would make the graphic formula of potassium acid fluoride, cryolite, etc. ... 

Gravimetric Methods.—The mixture of pentoxides of niobium and tantalum is redissolved in concentrated hydrofluoric acid and separated by Marignac s process (see p. 128) the potassium tantalum fluoride and potassium niobium oxyfluoride are then separately converted into the pentoxides as described above, and -weighed.1 This method has several disadvantages (1) The ratio of the solubilities of the two compounds on which the separation is based is only approximately 10 1, and the process is, therefore, necessarily inaccurate even when the recrystaflisation is repeated to a tedious extent the error approaches 1 per cent. (2) The concentration of the hydrofluoric add and of the potassium fluoride must be carefully controlled if the acidity is too low, an oxyfluoride of tantalum is precipitated if the acidity is too great, a normal fluoride of niobium is obtained. (3) Several platinum dishes are necessary. 

The estimation of small quantities of tantalum in niobium compounds is more difficult, and cannot be carried out colorimetrically. The usual method is to convert the material into the potassium double fluoride, and then to take advantage of the fact that a white precipitate of potassium tantalum oxyfluoride, K4Ta405F14 (see p. 132), is thrown down when a solution of potassium tantalum fluoride, KaTaF7, is boiled.7 Powell and Schoeller 8 find this test imperfect, and have modified the procedure (based on the differential hydrolytic dissociation of oxalo-niobic acid and oxalo-tantalic acid in the presence of tannin in slightly add solution) for the detection and estimation of traces of tantalum in niobium compounds. 

Rubidium Tantalum Fluoride, 2RbF.TaFB or RbaTaF is obtained in white needles similarly to the analogous potassium compound. It dissolves in 40 parts of water.3... 

Other methods of preparation. For each of the hydrogen compounds of the halogens there are certain specific methods that may be used to advantage in the laboratory Thus, hydrogen fluoride may be produced by heating potassium hydrogen fluoride ... 

Potassium hydrogen fluoride, KF, HF.—Potassium fluoride combines with hydrofluoric acid to form a primary fluoride, KF,HF or KHF2, crystallizing in tetragonal plates, and decomposed at red heat with evolution of hydrofluoric acid. Its heat of formation13 from the fluoride and hydrogen fluoride is 21-1 Cal., and its heat of solution is -6-0 Cal. Other unstable compounds of potassium fluoride with 2 and with 3 molecules of hydrogen fluoride have been prepared.14... 

Berzelius also tried to isolate silicon using a method similar to that of Davy s. He mixed molten (melted) potassium metal with a compound known as potassium silicon fluoride (K2SiFg). The procedure was successful in producing pure silicon. 

The material discovered by Klaproth was not a pure element. Instead, it was a compound of zirconium and oxygen, zirconium oxide (Zr02). The pure metal was not produced until 1824 when Swedish chemist Jons Jakob Berzelius (1779—1848) made fairly pure zirconium. He made the metal by heating a mixture of potassium and potassium zirconium fluoride (ZrK2p6) ... 

Moissan, Henri. (1852-1907). A Native of Paris, Moissan was a professor at the School of Pharmacy from 1886 to 1900 and at the Sorbonne from 1900 to 1907. At the former institution, he first isolated and liquefied fluorine in 1886 by the electrolysis of potassium acid fluoride in anhydrous hydrogen fluoride. His work with fluorine undoubtedly shortened his life as it did that of many other early experimenters in the field of fluorine chemistry. He won great fame by his development of the electric furnace and pioneered its use in the production of calcium carbide, making acetylene production and use commercially feasible in the preparation of pure metals, such as magnesium, chromium, uranium, tungsten etc. and in the production of many new compounds, e.g., silicides, carbides, and refrac-... 

ZIRCAT (7440-67-7) Finely divided material is spontaneously flammable in air may ignite and continue to bum under water. Violent reactions with oxidizers, alkali hydroxides, alkali metals (and their compounds), carbon tetrachloride, cupric oxide, lead, lead oxide, lead peroxide (combined material can burn explosively, and is sensitive to friction and static electricity), nitryl fluoride, oxygen difluoride, phosphoms, potassium, potassium compounds (potassium chlorate, potassium nitrate), sodium borate, sodium hydroxide. Explodes if mixed with hydrated borax when heated. Contact with lithium chromate may cause explosion above 752°F/450°C. Forms explosive mixture with potassium chlorate. Dusts of zirconium ignite and explode in a carbon dioxide atmosphere. Contact with ammonium-V-nitrosophenylhydroxylamine above 104°F/40°C forms an explosive material. Incompatible with boron, carbon, nitrogen, halogens, lead, platinum, potassium nitrate. In case of fire, use approved Class D extinguishers or smothering quantities of dry sand, crushed limestone, clay. 

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