Antimony tungstates

Leyrie, Synthesis and chemical behavior of the inorganic cryptates. Ammonium, alkali, and alkaline earth antimony tungstates [MSb9W2i084 " Mn = Na, K, NH4, Ca, Sr, Inorg. Nucl. Chem. 42 1583(1980)... 

Stannic and stannous, see under Tin Stibine, see Antimony hydride Stibnite, see Antimony(III) sulflde Stolzite, see Lead tungstate(VI)(2—)... 

Arsenites may also be determined by this procedure but must first be oxidised by treatment with nitric acid. Small amounts of antimony and tin do not interfere, but chromates, phosphates, molybdates, tungstates, and vanadates, which precipitate as the silver salts, should be absent. An excessive amount of ammonium salts has a solvent action on the silver arsenate. 

Discussion. The procedure is based on the formation of yellow tetraiodo-antimonate(III) acid (HSbI4) when antimony(III) in sulphuric acid solution is treated with excess of potassium iodide solution. Spectrophotometric measurements may be made at 425 nm in the visible region or, more precisely, at 330 nm in the ultraviolet region. Appreciable amounts of bismuth, copper, lead, nickel, tin, tungstate, and molybdate interfere. 

W-Sb oxides were prepared by mixing aqueous solutions of ammonium tungstate and antimony tartarate, followed by drying in an air-circulated oven at 120 C and then calcination at 650 C. 

For the analysis of complex tungstates containing arsenic, antimony, or vanadium, see Sweeney, J. Amor. Chem. Soc., 1916, 38, 2377. 

The carbonates, sulphates, and borates are decomposed. The sulphides of the alkalies and alkaline earths are decomposed while the sulphides of arsenic, antimony, molybdenum, zinc, cadmium, tin, iron, lead, copper, mercury, and palladium are not attacked. Cobalt sulphate is not attacked, while the sulphates of the alkalies and alkaline earths are attacked and dissolved. Alkali tungstates, ammonium arsenite and arsenate, copper arsenite, ammonium magnesium arsenate, ammonium molybdate and vanadate, potassium cyanide and ferrocyanide are decomposed. Paraffin is not attacked shellac, gum arabic, gum tragacanth, copal, etc., are decomposed. Celluloid is slowly attacked. Silk paper, gun cotton, gelatin, parchment are dissolved. M. Meslans 22 has studied the esterification of alcohol by hydrofluoric acid. 

Tungsten resembles molybdenum in showing a remarkable ability to form complex compounds. One molecule of an alkali oxide may be combined with 1, 2, 3, 4, 5, 6, or 8 molecules of WO3 while more complex molecules may contain as much as 5Mr20 condensed with varying amounts of WOa. There are also formed many series of complex tungstates in which W03 combines with varying proportions of the oxides of silicon, phosphorus, arsenic, antimony, vanadium, and boron,... 

Small amounts of iron do not interfere. Mercury, gold and thallium chlorides, and any basic bismuth chloride, precipitated by hydrolysis, likewise molybdates and tungstates in acid solution, give color reactions with Rhodamine B similar to those given by antimony salts. 

If a freshly prepared benzene solution of the dyestuff is used rather than an aqueous solution of Rhodamine B, it is possible to detect as little as 0.05 y antimony in drops (1 1,000,000). Under these conditions, however, red benzene solutions are given by bismuth, gold, and mercury salts, and also by molybdates and tungstates, though only to a slight extent. 

Finally, the unusual mineral condensed ions (MCIs) certainly qualify as inorganic salts, and these polyanions formed from tungstate or molybdate (as MO4") and central ions such as silicon and antimony are being studied... 

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