Barium dithionate, preparation

Hydrazine Ditfaionate, N2H4.H2S2Oa, a polymer of amidosul-phonic acid, may be prepared by the interaction of hydrazine sulphate and barium dithionate. It is obtained as large crystals. On evaporation over sulphuric acid it decomposes with separation of sulphuric anhydride and is converted into a mixture of hydrazine sulphate and secondary hydrazine dithionate, (N3H4)2.H3S306.a... 

Vanadyl Dithionate, VOS2Oe, is prepared by treating a solution of vanadyl sulphate with barium dithionate. It decomposes on standing, with evolution of sulphur dioxide.2... 

Nickel Oithionate, NiS206.6H20, may be prepared by double decomposition of barium dithionate and nickel sulphate solutions.6 On concentration of the filtered solution, green triclinic prisms separate out. From its solution ammonia precipitates the hexammoniate, NiS206.6NH3. 

Potassium dithionate, K2S206.—The dithionate is prepared by the interaction of barium dithionate and potassium carbonate. It forms hexagonal crystals, of density 4 2-278 at 20° C. The heat of formation from the elements is 415-72 Cal.5 At 16° C. the solubility is 6-06 grams per 100 grams of water.6... 

When sulphur dioxide reacts with an aqueous suspension of manganese dioxide, manganese dithionate is formed. When this is treated with barium hydroxide, the barium dithionate is left in solution when manganese(Il) hydroxide separates. Alkali metal or ammonium dithionates are prepared from a solution of the barium dithionate in an ion-exchange column. 

In dithionic acid and dithionates, 8205 , the oxidation state of the 2 8 atoms has been reduced from VI to V by the formation of an 8-8 bond (Table 15.18, p. 705). The free acid has not been obtained pure, but quite concentrated aqueous solutions can be prepared by treatment of the barium salt with the stoichiometric amount of H28O4 ... 

The procedure used in the preparation of calcium dithionate is followed except that barium hydroxide is employed instead of calcium hydroxide. For the amounts specified for calcium dithionate, the initial quantity of barium hydroxide, Ba(OH)2 8H20, should be about 160 g. Because of the greater solubility of barium hydroxide, greater care must be exercised in arriving at the end point (strong alkalinity to litmus paper). 

The crude dithionate solution is prepared in accordance with the instructions given for calcium dithionate. This solution is brought to a temperature of 35 to 40°. With continuous agitation, barium carbonate powder is added a little at a time until ftui,her addition does not cause immediate increase in carbon dioxide evolution. Agita-... 

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