Sodium paramolybdate

Preparation of Sodium Paramolybdate. Pour 20 ml of a sodium molybdate solution into a 100-ml beaker. Heat the solution and introduce freshly precipitated molybdic acid into it in small portions with stirring until it stops dissolving. Filter the solution and evaporate it in a water bath until crystallization of a sample taken begins. 

Thallous Paramolybdate, SThO.OMoOg, is obtained as a yellow microerystalline precipitate when excess of hot thallous sulphate solution is added to a hot solution of sodium paramolybdate. The salt is slightly soluble in water, readily soluble in mineral acids and in alkalies. On heating it deepens in colour, and melts at red heat to a dark brown liquid. Thallous paramolybdate is interesting in that it is unusual to ol)tain paramolybdates in the anhydrous condition. 

A solution of sodium paramolybdate 5 NagO 12 M0O3 aq. is treated with the stoichiometric quantity of AsgOs. and the salt... 

A solution of sodium paramolybdate is prepared by dissolving three moles (431.9 g.) of M0O3 in three moles (120.0 g.) of NaOH. One mole of H3ASO4 is added, and the clear solution is gradually treated with one mole of HCl. The desired salt crystallizes out on concentrating the solution. 

Cadmium Molybdates.— The normal salt CdMoO is obtained as a heaY-y white precipitate when a soluble cadmium salt is added to a solution of an alkali molybdate or paramolybdate. The precipitate is readily soluble in mineral acids, ammonium hydroxide, or aqueous potassium cyanide. By fusing together sodium molybdate (2 parts), cadmium chloride (7 parts), and sodium chloride (6 parts), the salt may be obtained as lustrous yellow crystals. ... 

Sodium Trimolybdate, NaoMOgOjo-fPlTHgO. crjstallises from a saturated solution of molybdenum trioxide in sodium carbonate,or from such a solution treated with a suitable excess of nitric acid or it may be obtained by the addition of a large excess of acetic acid to a solution of the paramolybdate.The trimolybdate yields fine needles which at 100° C. lose 6HjO it is rather more soluble in hot than in cold water. 

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