Potassium metavanadate

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Crystal compoundsSaltsVanadatesPotassium metavanadate


  Potassium metavanadate   
Names: potassium metavanadate
potassium vanadate
potassium trioxovanadate

Formula: KVO3 (anhydrous)
KVO3 · H2O (monohydrate)
SMILES: [O-][V](=O)=O.[K+]
Molar mass: 138.037 g/mol (anhydrous)
156.052 g/mol (monohydrate)
Density: 2.84 g/cm3 (anhydrous)
Crystal system: orthorhombic (anhydrous)
a=5.78 Å
5.7800 Å
0.5780 nm
, b=10.794 Å
10.7940 Å
1.0794 nm
, c=5.176 Å
5.1760 Å
0.5176 nm
α=90°
90°  
, β=90°
90°  
, γ=90°
90°  

orthorhombic (monohydrate)
a=8.15 Å
8.1500 Å
0.8150 nm
, b=13.58 Å
13.5800 Å
1.3580 nm
, c=3.96 Å
3.9600 Å
0.3960 nm
α=90°
90°  
, β=90°
90°  
, γ=90°
90°  

Shapes:
https://media.crystalls.info/w/uploads/media/Spherolit.json
https://media.crystalls.info/w/uploads/media/Needle.json

Color: colorless
pale yellow surface
Melting point: 528 °C
801.15 K
982.4 °F
1,442.07 °R
(anhydrous)
Magnetic properties: diamagnetic
Stability: stable (monohydrate)
slightly hygroscopic (anhydrous)
Hardness: fragile
Toxicity: highly toxic
LD50~100mg/kg

Description

Inorganic compound, salt of alkaline metal potassium and inorganic metavanadic acid. From water solutions crystallizes as monohydrate.

Precursors

Reaction between potassium hydroxide and vanadium pentaoxide

Chemical equation:

2KOH + V2O5 = 2KVO3 + H2O

For preparation of 100.00g of potassium metavanadate monohydrate а 58.28g of vanadium pentaoxide and 35.95g of potassium hydroxide is required.
Add to flask with hot concentrated solution of hydroxide potassium small amount of vanadium pentaoxide with intense stirring. Heat it to 100°C for few minutes for reaction completion and then filter out. For purifying compound from hydroxide add large amount of cold ethanol, acetone or toluene to solution, salt will settle to the bottom in the form of fine crystals or powder. Filter precipitate and wash it with small amount of the same solvent, then filter the solution and use it for crystal growing.

Reaction between potassium hydroxide and ammonium metavanadate

Chemical equation:

KOH + NH4VO3 = KVO3 + H2O + NH3

For preparation of 100.00g of potassium metavanadate monohydrate а 74.96g of ammonium metavanadate and 35.95g of potassium hydroxide is required.
Add to the flask saturated solution of potassium hydroxide and then add small parts of hot ammonium metavanadate solution with heating and stirring. Emission of large amount of ammonia will begin.Attention, exuding ammonia irritates eyes and lungs! The synthesis should be carried out only in a fume hood or outdoors!

Notes

There are some redox processes occurring in solution, because of them the crystal surface could be slightly yellow.

Storage conditions

Store in its original form or under several layers of varnish at average humidity and room temperature. Do not store in matchboxes or cotton wool and do not heat.

Solubility

Temperatureгр/100,00 гр water
(anhydrous)(monohydrate)
0°C
273.15 K
32 °F
491.67 °R
1.4
1.4 g/100g
1.381 %
~1.6
1.6 g/100g
1.575 %
25°C
298.15 K
77 °F
536.67 °R
10.7
10.7 g/100g
9.666 %
~12.3
12.3 g/100g
10.953 %
Insoluble in ethanol, methanol, acetone, toluene and isopropanol.

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