Diphosphorus pentoxide

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Diphosphorus pentoxide

General
Other names phosphorus pentoxide
phosphoric anhydride
Molecular formula P₂O₅
Molar mass 141.94 g/mol
Appearance white powder
very deliquescent
pungent odor
CAS number [1314-56-3]
Properties
Density and phase 2.39 g/cm³, solid
Solubility in water exothermic reaction
Melting point 300-360°C
Boiling point ?
Vapor pressure 1 mm @ 384°C
Hazards
EU classification not listed
NFPA 704
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
[Chemical infoboxInfobox disclaimer and references]

Diphosphorus pentoxide is so called because of its empirical formula P₂O₅, as should be expected of any element in oxidation number +5.

In fact, later research shows that it is made up of molecules with formula P₄O₁₀, so may be called tetraphosphorus decoxide, but for most purposes, this is irrelevant; the historical name and formula have stuck.

Diphosphorus pentoxide is an extremely good dehydrating agent. When combined with a carboxylic acid, the result is an anhydride.

Conditions/substances to avoid when dealing with diphoshorus pentoxide are: moisture, ammonia, calcium oxide, chlorine trifluoride, hydrogen fluoride, oxygen difluoride, perchloric acid, chloroform, potassium, propargyl alcohol, sodium, sodium carbonate, sodium hydroxide, thallium(I) carbonate and water.

Fiction

In Anthony Burgess' The Wanting Seed, phosphorus pentoxide is a highly prized compound.

External links

For a full list of external links to MSDSs, spectroscopic data, commercial chemicals suppliers etc. for this compound, see [Chemical sources].

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Diphosphorus pentoxide

General
Other names	phosphorus pentoxide phosphoric anhydride
Molecular formula	P₂O₅
Molar mass	141.94 g/mol
Appearance	white powder very deliquescent pungent odor
CAS number	[1314-56-3]
Properties
Density and phase	2.39 g/cm³, solid
Solubility in water	exothermic reaction
Melting point	300-360°C
Boiling point	?
Vapor pressure	1 mm @ 384°C
Hazards
EU classification	not listed
NFPA 704
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) [Chemical infoboxInfobox disclaimer and references]