Preparation of Ammonium Fluovanadate III

Preparation of Ammonium Fluovanadate(III). Assemble an apparatus as shown in Fig. 115. Put a porcelain boat with 5 g of ammonium vanadate into quartz tube 5. Check the tightness of the 

Calculate the amount of ammonium difluoride needed to prepare ammonium fluovanadate(III). Take twice as much ammonium difluoride as calculated and melt it in a copper bowl. Perform the experiment in a fume cupboard, wear eye protection and glovesi) 

Introduce vanadimn(III) oxide into the melt while continuously stirring with a nickel spatula. Cool the melt. In an hour, grind the cooled green sinter in a porcelain mortar and again heat it in 

Preparation of Anhydrous Dioxovanadium Nitrate (VO2NO3). Prepare 7-10 ml of liquid nitrogen(IV) oxide (see p. 141). Mix the nitrogen(IV) oxide with 5-7 cm of dry acetonitrile in a test tube (see Fig. 92a). Add 0.3-0.5 g of metallic vanadium preliminarily crushed in a porcelain mortar to this mixture. Close the test tube with a stopper provided with a calcium chloride tube containing phosphoric anhydride. 

After 24 hours, distil off the excess nitrogen(II) oxide and acetonitrile on a water bath in a vacuum produced by a water-jet pump. Weigh the product and calculate its yield in per cent. 

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