fosforpentoksidet

Fosforpentoksidet, also known as phosphorus pentoxide, is the anhydride of phosphoric acid with the chemical formula P4O10. It is a white, crystalline solid that is highly hygroscopic and a very effective drying agent. In older literature it is sometimes represented by the empirical formula P2O5.

Structure and properties: The molecule consists of four phosphorus atoms connected by oxygen atoms in a cage-like arrangement, formed from PO4 tetrahedra linked by bridging oxygens. Each phosphorus is in the +5 oxidation state. The compound reacts vigorously with water, hydrolyzing to form phosphoric acid: P4O10 + 6 H2O → 4 H3PO4.

Preparation: Phosphorus pentoxide is prepared by the dehydration of phosphoric acid at elevated temperatures: 4 H3PO4 → P4O10 + 6 H2O. It can be handled and stored best in a dry, moisture-free environment.

Uses: It is widely used as a powerful drying agent for solvents and gases in chemical laboratories and manufacturing, effectively removing water from reacting systems. It also participates in dehydration reactions to form phosphate esters and related reagents and is a reagent in certain phosphate chemistry processes.

Safety and handling: Fosforpentoksidet is corrosive and reacts exothermically with water, forming phosphoric acid. It can cause severe irritation to skin, eyes, and the respiratory tract. It should be handled with appropriate protective equipment, and stored in tightly closed, moisture-free containers away from water and incompatible materials.

See also: phosphoric acid, dehydration reagents, phosphate esters.