BARIUM METAPHOSPHATE

Chemical properties

White powder. Slowly soluble in acids; insoluble in water.

The Uses of BARIUM METAPHOSPHATE

Barium metaphosphate, used in glasses, porcelains, and enamels, as a flame retardant and in phosphors applications.

The Uses of BARIUM METAPHOSPHATE

Glasses, porcelains, and enamels.

Preparation

Barium metaphosphate can be prepared by the solidstate reaction of metaphosphoric acid and the hydroxide, oxide or carbonate of barium:
BaCO3 + HPO3 + heat ? Ba(PO3)2 +H2O + CO2
The best temperature to use is about 700°C. It has the CAS number of 13762-83-9 and the molecular weight of 295.2709 g/mol. If diammonium phosphate is used instead of solid metaphosphoric acid, the product is not pure. Colored glasses are obtained caused by the reduction of P-atoms in the phosphate anion by hydrogen released from NH3 to form colloidal dispersions of P4 which produce various colors in the glass. b-Ba(PO3)2 is the final product. This compound can also be prepared by the aqueous reactions:
NaPO3 (aq) + BaCl2 (aq) ? Ba(PO3)2 (solid) + NaCl (aq)
or
Ba(OH)2 (solid) + 2HPO3 (aq) ? Ba(PO3)2 (solid) + 2H2O
The dissolution and reaction involving HPO3 are slow and should be carried out in a hot solution. Evaporation at a low temperature (<15°C) serves to form the crystals. The product involves several hydrates depending upon the conditions of precipitation. Anhydrous barium metaphosphate is a white porous powder or granular material that is insoluble in water.