Ammonium metavanadate

Ammonium metavanadate is the inorganic compound with the formula NH₄VO₃. It is a white salt, although samples are often yellow owing to impurities of V₂O₅. It is an important intermediate in the purification of vanadium.^[2]

Ammonium vanadate

Ammonium vanadate
Photo of a sample of ammonium vanadate
Names
IUPAC name Ammonium trioxovanadate(V)
Other names Ammonium vanadate
Identifiers
CAS Number	7803-55-6 Y
3D model (JSmol)	Interactive image
ChemSpider	19968892 Y
ECHA InfoCard	100.029.329
PubChem CID	516859
RTECS number	YWD875000
UNII	FL85PX638G Y
UN number	2859
CompTox Dashboard (EPA)	DTXSID1052533
InChI InChI=1S/H3N.3O.V/h1H3;;;;/q;;;;-1/p+1 Y Key: UXJVWJGDHIZPLD-UHFFFAOYSA-O Y InChI=1/H3N.3O.V/h1H3;;;;/q;;;;- 1/p+1/rH3N.O3V/c;1-4(2)3/h1H3;/q;-1/p+1 Key: UXJVWJGDHIZPLD-KKTKNITLAZ
SMILES [NH4+].O=[V-](=O)=O
Properties
Chemical formula	NH4VO3
Molar mass	116.98 g/mol
Appearance	white
Density	2.326 g/cm3
Melting point	>200 °C (392 °F; 473 K)[1] (decomposes)
Solubility in water	4.8 g/100 ml (20 °C)[1]
Solubility	soluble in diethanolamine, ethanolamine
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	possible mutagen, dangerous for the environment
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H332, H340, H361, H370, H372, H412
Precautionary statements	P201, P202, P260, P261, P264, P270, P271, P273, P281, P301+P310, P304+P312, P304+P340, P307+P311, P308+P313, P312, P314, P321, P330, P405, P501
NFPA 704 (fire diamond)	4 0 0
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (median dose)	58.1 mg/kg, oral (rat)
Related compounds
Other anions	Ammonium orthovanadate Ammonium hexavanadate
Other cations	Sodium metavanadate Potassium metavanadate
Related compounds	Vanadium pentoxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Synthesis and structure

The compound is prepared by the addition of ammonium salts to solutions of vanadate ions, generated by dissolution of V₂O₅ in basic aqueous solutions, such as hot sodium carbonate. The compound precipitates as a colourless solid.^[3][4] This precipitation step can be slow.

The compound adopts a polymeric structure consisting of chains of [VO₃]⁻, formed as corner-sharing VO₄ tetrahedra. These chains are interconnected via hydrogen bonds with ammonium ions.^[5]

ball-and-stick model	polyhedral model	[(VO3)n]n− chains

Uses

Vanadium is often purified from aqueous extracts of slags and ore by selective precipitation of ammonium metavanadate. The material is then roasted to give vanadium pentoxide:^[2]

2 NH₄VO₃ → V₂O₅ + 2 NH₃ + H₂O

Other

Vanadates can behave as structural mimics of phosphates, and in this way they exhibit biological activity.^[6][7]

Ammonium metavanadate is used to prepare Mandelin reagent, a qualitative test for alkaloids.^[8]