Ammonium tungsten fluoride

It was originally separated from zirconium by repeated recrystallization of the double ammonium or potassium fluorides by von Hevesey and Jantzen. Metallic hafnium was first prepared by van Arkel and deBoer by passing the vapor of the tetraiodide over a heated tungsten filament. Almost all hafnium metal now produced is made by reducing the tetrachloride with magnesium or with sodium (Kroll Process). 

Lanthanum in purified metallic state may be obtained from its purified oxide or other salts. One such process involves heating the oxide with ammonium chloride or ammonium fluoride and hydrofluoric acid at 300° to 400° C in a tantalum or tungsten crucible. This is followed by reduction with alkali or alkaline earth metals at 1,000°C under argon or in vacuum. 

FLINAK is purified by treatment with the HF released by ammonium bifluoride (NH4HF2) the HF converts oxide impurities in the melt to H20 [7]. In this purification procedure, the fluoride salt mixture is combined with 15 wt% NH4HF2 and heated to about 500°C in a graphite crucible. The molten mixture is poured into a platinum container and heated to 750°C. Hydrogen is passed through the molten mixture for approximately 2 days. Further purification can be achieved by con-trolled-potential electrolysis at an applied potential of about 3 V between a tungsten cathode and glassy carbon anode. 

Bradfield and Stickland [40,41] determined molybdenum in plant tissue by its catalytic effect on the liberation of iodine from the reaction between potassium iodide and hydrogen peroxide. The detection limit is 0.003 pg/ml of molybdenum. Interference from iron and tungsten can be overcome by addition of ammonium fluoride, but for the greatest precision and accuracy a preliminary separation of molybdenum as its benzoin a-monoxime complex is recommended. 

FeTe Tellurium(VI) fluoride, 1 121 F V(NH4)3 Ammonium hexa-fluorovanadate(III), 7 88, 89 FsW Tungsten (VI) fluoride, 3 181 FeBrj-flNHs Iron (II) bromide, 6-ammoniate, 4 161 Fe(CH02)j-2Hs0 Iron(II) formate, 4 159... 

Tungsten hexafluoride 232-033-3 Silver chloride 232-051-1 Aluminum fluoride 232-055-3 Ammonium alum Unichem AMAL 232-056-9 Albrite MALP Aluminum orthophosphate 232-059-5 Arsenic trichloride 232-061-6... 

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