- a white, deliquescent, crystalline powder, P2O5, that, depending upon the amount of water it absorbs, forms orthophosphoric acid, metaphosphoric acid, or pyrophosphoric acid, produced by the burning of phosphorus in dry air: used in the preparation of phosphoric acids, as a drying and dehydrating agent, and in organic synthesis.
- a white odourless solid produced when phosphorus burns: has a strong affinity for water with which it forms phosphoric acids. Formula: P 2 O 5 (commonly existing as the dimer P 4 O 10)
