Dinitrogen tetroxide

Dinitrogen tetroxide, also known as nitrogen tetroxide or dinitrogen tetraoxide, is a chemical compound. Its chemical formula is N2O4. It contains nitrogen in its +4 oxidation state. It contains nitrogen and oxide ions.
Properties.
It is a colorless gas, although it is sometimes polluted with nitrogen dioxide. It is very corrosive and a strong oxidizing agent. It can ignite on contact with hydrazine. It can be made by bonding two nitrogen dioxide molecules together at a low temperature or a high pressure.
Preparation.
It is made by bonding nitrogen dioxide molecules together in pairs.
Uses.
It is used as a rocket propellant, along with hydrazine. This mixture is good since it does not have to be ignited. It is used similar to nitrogen dioxide to make nitric acid. It can react with metals to make nitrates.
Safety.
Dinitrogen is highly toxic and corrosive. Some astronauts breathed it and had to go to a hospital.