Editing Nitrogen (section)

===Hydrides===
[[File:Nitrogen electrode potentials.svg|thumb|right|upright=2.3|Standard reduction potentials for nitrogen-containing species. Top diagram shows potentials at pH&nbsp;0; bottom diagram shows potentials at pH&nbsp;14.<ref name="Greenwood434">Greenwood and Earnshaw, pp. 434–38</ref>]]
Industrially, [[ammonia]] (NH<sub>3</sub>) is the most important compound of nitrogen and is prepared in larger amounts than any other compound because it contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilisers. It is a colourless alkaline gas with a characteristic pungent smell. The presence of [[hydrogen bonding]] has very significant effects on ammonia, conferring on it its high melting (−78&nbsp;°C) and boiling (−33&nbsp;°C) points. As a liquid, it is a very good solvent with a high heat of vaporisation (enabling it to be used in vacuum flasks), that also has a low viscosity and electrical conductivity and high [[dielectric constant]], and is less dense than water. However, the hydrogen bonding in NH<sub>3</sub> is weaker than that in H<sub>2</sub>O due to the lower electronegativity of nitrogen compared to oxygen and the presence of only one lone pair in NH<sub>3</sub> rather than two in H<sub>2</sub>O. It is a weak base in aqueous solution ([[acid dissociation constant|p''K''<sub>''b''</sub>]] 4.74); its conjugate acid is [[ammonium]], {{chem|NH|4|+}}. It can also act as an extremely weak acid, losing a proton to produce the amide anion, {{chem|NH|2|-}}. It thus undergoes self-dissociation, similar to water, to produce ammonium and amide. Ammonia burns in air or oxygen, though not readily, to produce nitrogen gas; it burns in fluorine with a greenish-yellow flame to give [[nitrogen trifluoride]]. Reactions with the other nonmetals are very complex and tend to lead to a mixture of products. Ammonia reacts on heating with metals to give nitrides.<ref name="Greenwood420">Greenwood and Earnshaw, pp. 420–26</ref>

Many other binary nitrogen hydrides are known, but the most important are [[hydrazine]] (N<sub>2</sub>H<sub>4</sub>) and [[hydrogen azide]] (HN<sub>3</sub>). Although it is not a nitrogen hydride, [[hydroxylamine]] (NH<sub>2</sub>OH) is similar in properties and structure to ammonia and hydrazine as well. Hydrazine is a fuming, colourless liquid that smells similar to ammonia. Its physical properties are very similar to those of water (melting point 2.0&nbsp;°C, boiling point 113.5&nbsp;°C, density 1.00&nbsp;g/cm<sup>3</sup>). Despite it being an endothermic compound, it is kinetically stable. It burns quickly and completely in air very exothermically to give nitrogen and water vapour. It is a very useful and versatile reducing agent and is a weaker base than ammonia.<ref name="Greenwood426" /> It is also commonly used as a rocket fuel.<ref name="Vieira">{{cite journal | last = Vieira | first = R. |author2=C. Pham-Huu |author3=N. Keller |author4=M. J. Ledoux | year = 2002 | title = New carbon nanofiber/graphite felt composite for use as a catalyst for hydrazine catalytic decomposition | journal = [[Chemical Communications]] | issue = 9 | pages = 954–55 | doi = 10.1039/b202032g| pmid = 12123065 }}</ref>

Hydrazine is generally made by reaction of ammonia with alkaline [[sodium hypochlorite]] in the presence of gelatin or glue:<ref name="Greenwood426">Greenwood and Earnshaw, pp. 426–33</ref>
:NH<sub>3</sub> + OCl<sup>−</sup> → NH<sub>2</sub>Cl + OH<sup>−</sup>
:NH<sub>2</sub>Cl + NH<sub>3</sub> → {{chem|N|2|H|5|+}} + Cl<sup>−</sup> (slow)
:{{chem|N|2|H|5|+}} + OH<sup>−</sup> → N<sub>2</sub>H<sub>4</sub> + H<sub>2</sub>O (fast)
(The attacks by hydroxide and ammonia may be reversed, thus passing through the intermediate NHCl<sup>−</sup> instead.) The reason for adding gelatin is that it removes metal ions such as Cu<sup>2+</sup> that catalyses the destruction of hydrazine by reaction with [[monochloramine]] (NH<sub>2</sub>Cl) to produce [[ammonium chloride]] and nitrogen.<ref name="Greenwood426" />

[[Hydrogen azide]] (HN<sub>3</sub>) was first produced in 1890 by the oxidation of aqueous hydrazine by nitrous acid. It is very explosive and even dilute solutions can be dangerous. It has a disagreeable and irritating smell and is a potentially lethal (but not cumulative) poison. It may be considered the conjugate acid of the azide anion, and is similarly analogous to the [[hydrohalic acid]]s.<ref name="Greenwood426" />