Phosphorus (III) oxide

Phosphorus (III) oxide . According to stock nomenclature, also known by the systematic nomenclature as diphosphorous trioxide, and by the traditional nomenclature as phosphorous anhydride or phosphorous oxide, it is presented in a simple monomeric form whose stoichiometric formula is (P 2 O 3 ) and its dimers, present as formula molecular (P 4 O 6 ) can be considered as the anhydride of the phosphorous acid forms a crystalline mass of colored white, has feature acid medium and is the anhydride of the unstable tautomer acidphosphorous. It is also a ligand for transition metals.


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  • 1 Structure
  • 2 Physical properties
  • 3 Obtaining
  • 4 Chemical properties
  • 5 References
  • 6 Sources


Its structure is a modification of the tetrahedron P 4 , by inserting one atom of oxygen between two of [phosphorus]]

Physical properties

Phosphorus (III) oxide with a molar mass of 110g / mol is considered as the anhydride of the so-called phosphorous acids. It forms a white, wax-like crystalline mass that melts at 23.8 ºC with the formation of a relatively little volatile liquid (in Cuba phosphorus (III) oxide is normally in the liquid state), like the white phosphorus, this oxide is very toxic.


Phosphorus (III) oxide is produced by the combustion of Phosphorus P 4 (s) + 3O 2 (g) = P 4 O 6 (l) When the oxide is heated to about 200ºC in a vacuum it is transformed into phosphorus tetroxide along with red phosphorous.

Chemical properties

Phosphorus (III) oxide slowly combines with dioxygen at ordinary temperature and at low pressures, its oxidation produces phosphorescence. Phosphorous (III) oxide in the gaseous state induces ionization of the surrounding air.

Reacts slowly with cold water with phosphorous acid formation

4 O 6 (l) + H 2 O (cold) = 2H 3 PO 4 (ac)

With hot water a vigorous decomposition of phosphine (phosphamine) and phosphoric acid takes place

4 O 6 (l) + 6H 2 O (hot) = 3H 3 PO 4 (ac) + PH 3 (g)

With Hydrogen Chloride phosphorous trichloride and phosphorous acid

4 O 6 (l) + 6HCl (g) = 2H 3 PO 3 (ac) + PCl 3 (ac)

It also reacts vigorously with di Chlorine , and di Bromo .


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