Nitrogen Monoxide Formula

Nitrogen monoxide, also known as nitric oxide or nitrogen (II) oxide, is an oxide that is used in many industrial chemical processes. It also has a physiological role as a signaling molecule.

Formula and structure: The nitrogen monoxide chemical formula is NO. The molar mass is 30.01g/mol. The molecule is formed by one nitrogen atom N and one oxygen atom O. The nitrogen and the oxygen atoms are bound through a double bond. Although, it is in resonance with a structure formed by a triple bond. The geometry of the molecule is linear. Its chemical structure can be written as below, in the common representations used for organic molecules.

Occurrence: Nitrogen monoxide is present in nature. It is formed in the organism through the action of the enzyme nitric oxide synthase, using as a precursor the amino acid L-arginine.

Preparation: Nitrogen monoxide is synthesized by the reaction of nitrogen gas and air, catalysed by an electric arc. It can also be formed by the reaction of oxidation of ammonia, catalysed by platinum and a temperature above 500 °C:

4 NH₃ + 5 O₂ → 4 NO + 6 H₂O

Physical properties: Nitrogen monoxide is a colourless and odourless gas. The density of this gas is 1.340 g/mL. Its melting point is -164 °C and its boiling point is -152 °C. It is slightly soluble in water but it is soluble in ethanol, ether and sulfuric acid.

Chemical properties: Nitrogen monoxide is a highly reactive molecule. One of the most interesting reactions are described in this section. It can dimerize to form dinitrogen trioxide N₂O₂. The nitrogen monoxide can also react with air to form nitrogen dioxide. While the reaction with water produces nitrous acid:

2 NO + O₂ → 2 NO₂

4 NO + O₂ + 2 H₂O → 4 HNO₂

Uses: Nitrogen monoxide is a molecule known for its environmental effects. It is one of the causes if the acid rain, which is formed through a reaction with the hydroperoxy radical. Nitrogen monoxide is also part of the ozone layer depletion. It can be used in some chemical reactions as a precursor.

Health effects / safety hazards: Nitrogen monoxide is toxic by inhalation and it can cause eyes irritation. It is highly reactive and can react with other chemical compounds, so should be storage in adequate conditions. It is not flammable.