Editing Dinitrogen tetroxide (section)

==Production==
Nitrogen tetroxide is made by the [[catalytic oxidation]] of [[ammonia]] (the [[Ostwald process]]): steam is used as a [[diluent]] to reduce the combustion temperature. In the first step, the ammonia is oxidized into [[nitric oxide]]:
: 4 NH<sub>3</sub> + 5 O<sub>2</sub> → 4 NO + 6 H<sub>2</sub>O

Most of the water is condensed out, and the gases are further cooled; the nitric oxide that was produced is oxidized to nitrogen dioxide, which is then dimerized into nitrogen tetroxide:
: 2 NO + O<sub>2</sub> → 2 NO<sub>2</sub>
: 2 NO<sub>2</sub> ⇌ N<sub>2</sub>O<sub>4</sub>

and the remainder of the water is removed as [[nitric acid]]. The gas is essentially pure nitrogen dioxide, which is condensed into dinitrogen tetroxide in a brine-cooled liquefier.<ref>{{cite book |last1=Hebry |first1=TH |last2=Inskeep |first2=GC |title=Modern Chemical Processes: A Series of Articles Describing Chemical Manufacturing Plants |date=1954 |publisher=Reinhold |location=New York |page=219 |url=https://books.google.com/books?id=-L3nAAAAMAAJ |language=en}}</ref>

Dinitrogen tetroxide can also be made through the reaction of concentrated nitric acid and metallic copper. This synthesis is practical in a laboratory setting. Dinitrogen tetroxide can also be produced by heating metal nitrates.<ref>{{cite book |last1=Rennie |first1=Richard |title=A Dictionary of Chemistry |date=2016 |publisher=Oxford University Press |isbn=978-0-19-872282-3 |page=178 |url=https://books.google.com/books?id=d1sFCwAAQBAJ&pg=PA178 |language=en}}</ref> The oxidation of copper by nitric acid is a complex reaction forming various nitrogen oxides of varying stability which depends on the concentration of the nitric acid, presence of oxygen, and other factors. The unstable species further react to form nitrogen dioxide which is then purified and condensed to form dinitrogen tetroxide.