P2O5, which has a molecular mass of 141.9, can usually be found as its dimeric, P4O10. It reacts powerfully with water to form ortophosphoric acid, H3PO4. That is why it is called phosphorus anhydride at times. P2O5's reaction with water causes the release of much heat and choking white fumes.
P2O5, which appears as white powder or crystals, is highly corrosive and capable of causing damage to the respiratory tract, skin and eyes. Since P2O5 is a powerful dehydrating agent, it is frequently used for eliminating water during organic material synthesis. It can be prepared by burning phosphorus in very dry air.Learn more about Chemical Equations