Dinitrogen pentoxide

Dinitrogen pentoxide is a chemical compound made of nitrogen and oxygen with formula N₂O₅. The nitrogen has oxidation number +5 and the oxygen has oxidation number −2.

This substance has the form of white crystals. It is not stable and slowly decomposes into NO₂ (nitrogen dioxide) and O₂.

When mixed with water, dinitrogen pentoxide produces nitric acid (HNO₃), as such nitrogen pentoxide is the acidic anhydride of nitric acid. It is a white solid, a strong oxidising agent, but at room temperature it easily decomposes to nitrogen tetroxide and oxygen.