N2O5 is formally called dinitrogen pentoxide, or nitrogen pentoxide. It's a member of the group of nitrogen oxides, chemical compounds that consist solely of nitrogen and oxygen. A colorless, salt-like solid at room temperature, nitrogen pentoxide sublimates into a gas at 117 degrees Fahrenheit.
Nitrogen pentoxide is used in, or a result of, many chemical reactions and process; for example, it's a reagent in chloroform and an oxidizer in various types of explosives and pyrotechnics. Other nitrogen oxides are also abundant in the world. Several of these, despite being known air pollutants (such as nitrogen dioxide or NO2), are created as by-products of manufacturing or transportation.