Potassium tungstates

Potassium tungstate (ortho 2H2O) [37349-36-3] M 362.1. Crystd from hot water (0.7ml/g). 

Potassium tungstate(VI), K2WO<, for preparation of complex potassium chlorotungstates-(III), 6 149... 

A double hyd roxychloride of tungsten with potassium chloride has been prepared by the reduction with tin of a solution of potassium tungstate in concentrated hydrochloric acid after a series of colour changes the compound K2W(OH)CIg, which is stable in the dry condition, is obtained. 

The solution of normal potassium tungstate is strongly alkaline in reaction its density at various concentrations at 15° C. has been determined as follows ... 

Sodium Tungstates.—The anhydrous normal tungstate, NajWOi, is prepared by the fusion method described for potassium tungstate (see p. 222), or by complete dehydration of the hydrates at 100° C. or over sulphuric acid. It may be obtained from the mineral wolframite by fusion with alkali as already described (see p. 202). 

Engels has described a series of bronzes containing an alkali and an alkaline earth metal. These were prepared by electrolysis of the mass obtained bjf fusing commercial sodium or potassium tungstate with the calculated amount of metal carbonate. 

Potassium trUhiotiingstate, Iv2 OS3.H2O, is obtained in quadratic jilates by the ijrolonged action of hydrogen sulj)hide on potassium tungstate. It is very soluble in water, but may be precipitated by means of alcohol. The crystals deliquesce in a damp atmosphere and effloresce in a dry one. The solution gives a lemon-yello%v precipitate with zinc sulphate. 

K2W04 potassium tungstate 7790-60-5 25.00 3.1200 1 2407 MgH4N208 magnesium nitrate dihydrate 15750-45-5 25.00 1.4500 1... 

Potassium tungstate can be formed under the same conditions. 

Scheelite ores3 are easily decomposed by hydrochloric or nitric acid or, they may be fused with potassium fluoride,4 and the soluble potassium tungstate removed from the melt by leaching. 

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