Chemical reagent Tungstic acid

A polytungstic acid, colorless crystals. It belongs to 12-tungsten isopolyacids, the simple structural formula is H6[H2(W3O10)4]·nH2O, n is 10 or 23; the density is 3.93g/cm3, and it decomposes at 50 ℃; the solubility is very large, 88.57 g/100cm3 water (25℃). It is derived from the transformation of metatungstic acid salts. Metatungstate is an important industrial product developed in the late 1970s and is mainly used as a catalyst. Ammonium metatungstate can be obtained from ammonium paratungstate or from microcrystalline powdered scheelite. Many other metatungstates, including various metal salts and polycarbon ammonium salts, can be obtained directly or indirectly from microcrystalline powdered scheelite. Ammonium paratungstate is another polytungstate with simple structural formula (NH4)10[H2W12O42]·nH2O. It is prepared from sodium tungstate solution by ion exchange method, and no corresponding free acid can be obtained. Sodium-free tungsten trioxide can be obtained by burning a…