What is the chemical name for P4O10

di-phosphorus pentoxide P.4O10


White, highly hygroscopic crystalline powder
molar mass 283.92 g / mol

AGW 2 mg / m3 (TRGS 900)
Sublimation point +362 ° C  
Melting point (under pressure)
+562 ° C  
density 2.5 g / cm3   
Water solubility 
reacts violently with water
GHS 05
Hazard classes + category 

Corrosive / irritant effect on the skin 1A

HP rates(See note)    
H 314 P 260, 280.1-4 + 7, 303 + 361 + 353, 301 + 330 + 331, 305 + 351 + 338
disposal See note
print a labelGerman nameEnglish name
CAS 1314-56-3
di-phosphorus pentoxide, phosphorus (V) oxide
Phosphorus (V) oxide

Notes for schools: Phosphorus pentoxide must be kept dry and in pure form under all circumstances. With water there is a violent reaction with strong warming. The substance is very corrosive to the skin and eyes. Protective goggles and protective gloves made of nitrile rubber must be worn; face protection may also be necessary. Working in the fume hood is necessary because the dusts have a very aggressive effect on the mucous membranes and the respiratory tract.


Di-phosphorus pentoxide is a white, crystalline powder that immediately attracts moisture and sticks together when it comes into contact with air. It reacts violently with water with strong warming. First metaphosphoric acid is formed:

P.4O10 + H2O H4P.4O12
The addition of water results in several reaction steps ortho-Phosphoric acid. Phosphorus pentoxide can react explosively with alkali metals or with hydrogen peroxide. There are violent reactions with many other substances, and ignition is even possible with flammable substances, for example with alcohols, iodine and metals.


Phosphorus oxide is made by burning white phosphorus in a stream of air. If you hold white phosphorus in the air, it starts to smoke and phosphorus (V) oxide is already formed. When burning red phosphorus, phosphorus (V) oxide is obtained:

P.4 + 5 O2  P.4O10

White phosphorus begins to smoke in the air (left),
A white smoke is also produced when the red phosphorus is burned (right)


Due to its high reactivity with water, phosphorus pentoxide is an extremely effective drying agent in the chemical laboratory. In a desiccator, all humidity is removed by the desiccant, so that an anhydrous atmosphere is obtained.