Facts About Oxides of Nitrogen

Nitrogen Oxides are a combination of gases that contain Nitrogen and Oxygen. Nitric Oxide (NO) and Nitrogen Dioxide (NO2) are two of the most toxicologically significant chemicals. Nitrogen Monoxide (or Nitrous Oxide (N2O)) and Nitrogen Pentoxide (NO5) are two very common gases in this category.

Nitric Acid is produced from Nitrogen Dioxide. It is used to make fertilisers and manufacture explosives for military and mining purposes. The toxicity of Nitrous Oxide (N2O), also known as laughing gas, is distinct from other Nitrogen Oxides.

Nitric Oxide and Nitrogen Dioxide are the two of the riskiest Nitrogen Oxides. The latter is in equilibrium with its dimer, Nitrogen Tetroxide. At standard temperature, Nitric Oxide is a colourless gas that is slightly soluble in water. At ambient temperature, Nitrogen Dioxide is a colourless to brown liquid, and beyond 70 °F, it is a reddish-brown gas that is weakly soluble in water.

How are the oxides of Nitrogen produced?

Here are a few ways that can lead to the production of oxides of Nitrogen:

• Nitrogen Oxides are produced naturally when Nitrogen-containing materials such as coal, diesel fuel, and hay are oxidised. 

• Nitrogen Oxides can also be created through arc welding, engraving, electroplating, dynamite blasting, and nitration reactions like those used to make nitro-explosives like guncotton, dynamite, and TNT. 

• They are commercially manufactured, usually as the initial step in manufacturing Nitric Acid, by direct oxidation of ambient Nitrogen in an electric arc (Birkeland-Eyder Process) or catalytic oxidation of anhydrous ammonia (Ostwald Process). 

• Nitrogen Oxides are mostly formed in Nitric Acid and its solutions due to trace metal contaminants. 

• Nitrogen Oxides are critical components of photo-oxidant smog and are used as intermediates in the manufacture of lacquers, dyes, and other chemicals.

The only product of reactions in the furnace is Nitrogen Oxide (NO) (combined contents of (NO2) and (N2O) do not exceed 10 per cent in total). Then, NO is oxidised to (NO2). The leading player here is atmospheric ozone, which oxidises NO to the much more toxic (NO2). As a result, the maximum concentration of (NO2) is determined by the local concentration of ozone. It must be noted that NO emissions into the atmosphere are one of the most significant factors that lead to the destruction of the ozone layer. 

Nitrogen Oxides have a crucial role in several other environmental consequences, including acid rain and eutrophication in coastal waters, which can harm terrestrial and aquatic ecosystems.

• Acid rain is formed when (NO2) and other (NOx) react with water, Oxygen, and other compounds in the atmosphere. Acid rain also adversely affects sensitive habitats like lakes and forests.

• The nitrate particles produced by (NOx) make the air hazy and difficult to see through. 

• Nitrate also impacts numerous national parks, making it difficult for the wildlife to survive. 

• The presence of Nitrogen Oxide (NOx) in the atmosphere adds to nutrient contamination in coastal waters.

The Oxidation state of Nitrogen

In a neutral substance, the total of all the oxidation states of all the atoms or ions is zero.

The charge on an ion equals the total oxidation states of all the atoms in the ion.

A negative oxidation state is attributed to the more electronegative element in a material. A positive oxidation state is attributed to the less electronegative element.

The oxidation state of Nitrogen ranges from -3 to +5. 

Conclusion

Nitrogen Oxides (NOx) are among the six criteria of air pollutants that adversely affect humans and the environment. Air quality has deteriorated because of increased ambient air pollutants, particularly NOx over the last few decades because of fast industrial development. This data has allowed for the detection of patterns and seasonality, the identification of emissions sources, and the study of the chemistry and dynamics that govern NOx levels in the environment.