Ammonium pyrovanadate

Ammonium pyrovanadate does not appear to exist addition of... 

Sodium triperoxychromate Sodium peroxymolybdate Sodium peroxynickelate Sodium diperoxytungstate Potassium peroxyferrate Potassium peroxynickelate Potassium hyperoxytungstate Potassium peroxy pyrovanadate Calcium diperoxysulphate Calcium peroxychromate Zinc tetraaminoperoxydisulphate Ammonium peroxyborate Ammonium peroxymanganate Ammonium peroxychromate... 

The introduction of carbon dioxide into the solution removes the caustic soda (or, from the point of view of the ionic theory, the OH ions), so that the equilibrium is disturbed and the reaction then proceeds completely from left to right. Similarly, addition of ionised ammonium chloride suppresses the concentration of the OH ions already present in solution more of the pyrovanadate therefore undergoes hydrolysis, in order that the equilibrium concentrations of ions shall be maintained, until all the pyrovanadate is converted into metavanadate. 

Calcium Pyrovanadate, 2Ca2Va07.5Ha0, is formed by adding calcium chloride to a solution of sodium pyrovanadate and drying the precipitate at 100° C.6 The dihydrate, CaaVa07.2Ha0, has been obtained in transparent needles by adding calcium chloride to ammonium metavanadate solution and then excess of ammonium hydroxide.7... 

Lead Pyrovanadate, PbaVa07.—This salt is of interest in that it is the artificial form of descloizite, one of the important natural ores of vanadium. It is obtained by boiling mixed solutions of lead nitrate and ammonium metavanadate in the presence of acetic acid.11 A pale yellow basic pyrovanadate of lead, 2PbaVa07.PbO, is obtained by... 

Thorium Pyrovanadate, Th2V207.6H20, is greenish-yellow, and is obtained by the action of thorium chloride in dilute solution on ammonium metavanadate.1... 

Ammonium Orthothiovanadate, (NH4)3VS4, is obtained in rhombic crystals by the action of ammonium hydrosulphide on potassium metavanadate or sodium pyrovanadate solution. It also separates out slowly from an ice-cold saturated solution of ammonium metavanadate in concentrated ammonium hydroxide which has been previously treated with hydrogen sulphide. 

The gravimetric estimation of vanadium in alkaline vanadate solutions has also been effected by precipitating as ammonium metavanadate in the presence of ammonium chloride.6 Precipitation is incomplete, however, unless the solution is quite saturated with ammonium chloride 7 the addition of alcohol is recommended.8 Other gravimetric processes which have been investigated include the precipitation of barium pyrovanadate,9 precipitation of silver metavanadate,10 precipitation of manganese pyrovanadate,11 and the use of cupferron.12... 

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