Nitrogen oxides: definition, examples and education (2023)

Nitrogen is a colorless, odorless and tasteless element, diatomic molecular nitrogen (N₂) is a relatively inert gas that makes up about 80% of air. Nitrogen has a valence state of 1 to +5, so nitrogen can form a different type of oxide

Also read:class 12 nitrous

Key terms:Formation of nitrogen oxides,Nitrogen oxide emissions, nitrogen oxides, smog.

Nitrogen oxides are a gaseous mixture of nitrogen and oxygen. At high temperatures, oxygen and nitrogen fuse together.endothermicReaction that produces various oxides of nitrogen, but oxygen and nitrogen cannot react at low temperatures. The general term for nitrogen oxides is called NOx. The term NOx is commonly used to indicate that a molecule contains nitrogen and one or more oxygen atoms, but is actually a mixture of NO (nitrogen monoxide) and NO₂. Several types of nitrogen oxides are present in this environment, having a valence state from 1 to 5, for example:

• Lachgas (N₂Ö)
• Nitrous Oxide (NO)
• Nitrous Dioxide (N₂o₂)
• Nitrous oxide (N₂o₃)
• Nitrogen dioxide (NO2)
• Nitrous oxide (N₂o₄)
• Nitrous oxide (N₂o₅)

All NOx gases are harmful to health and the environment. Among the environmental pollutants among nitrogen oxides are nitrous oxide (N₂O), nitric oxide (NO) and nitrogen dioxide (NO₂).Nitrogen monoxide (NO) and nitrogen dioxide (NO₂) form smog, acid rain and ozone at ground level, causing air pollution. These oxides are formed in different ways, such as: B. Combustion of fossil fuels (i.e. coal, diesel, gasoline, etc.), acid manufacturing, explosives industry, and acid pickling plants, the primary source being emissions from vehicles and power plants. But it is not only formed artificially, because some natural processes such as lightning and biogenic processes such as the microbial process in the soil also cause the production of nitrogen oxides. This particular section is part of unit 7, elements of block p, and has a total weight of 7 points and 6 to 7 points.

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NOx formation

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The NOx generated by lightning per year is 8.6 million tons, but the NOx emissions generated by fossil fuels and combustion are 28.5 million. Agricultural fertilization and use of nitrogen fixing plants from atmospheric NOx through nitrogen fixation by microorganisms. Nitrogen fertilizer added to excess soilAmmoniaand nitrate, which is not used by plants, can be converted to nitrogen oxide (NO) by soil microorganisms. Sometimes ammonia is converted to nitrate through the process of nitrification. Nitrate reduced to nitrite, then nitric oxide (NO), then nitrous oxide (N₂O) Finally, this process releases nitrogen into the atmosphere, NOx. The reverse process of nitrification (denitrification). At the time of lightning, the rapid recovery and cooling of the gases creates nitrogen oxides (NO), which rapidly react with more oxygen to produce nitrogen dioxide (NO).₂). In cities, NOx is mainly produced by burning fossil fuels. During the combustion process of fossil fuels, nitrogen from the air and fuel reacts with oxygen to form nitrous oxide (NO), nitrous oxide (N₂O), nitrogen dioxide (NO₂) and other nitrogen oxides are formed in smaller amounts.

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Nitrogen oxide emissions from coal combustion can come from three sources

1)Thermal NOx:This NOx is formed when nitrogen and oxygen in the combustion air combine at high temperature, increasing NOx formation above 2800 degrees Fahrenheit flame temperature.

2)Combustible NOx:Reaction of bound nitrogen in the fuel with oxygen in the combustion air, a problem with gaseous fuels.

3)Request NOx:This type of NOx is formed by the rapid reaction of atmospheric nitrogen with hydrocarbon radicals. This formation of NOx is minor compared to the other two types of NOx.

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NOx Effects

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1)acid rain: Nitrogen oxides are one of the causes of acid rain, theseOxideWhen released into the air, they are further oxidized and eventually absorbed into water vapor to form a mist. When the clouds are saturated, acid mists precipitate in the form of acid rain. Acid rain destroys the fertility of the soil and also damages the leaves of trees and plants, increases the mortality of fish, affects paint and causes yellowing of white fabrics. Acid rain is more dangerous for concrete because it destroys its alkaline aggregate and cement structure.

stable molecule N₂y-oh₂conversion to a significant amount of NO occurs at high temperature.

NOx from lightning can be oxidized to produce nitric acid (HNO).₃) this precipitates as acid rain.

o₃+NO₂-> NO₃+ Ö₂

(ozone+nitrogen dioxide->nitrogen trioxide+oxygen)

NO₃+NO₂->N₂o₅

(nitrogen trioxide + nitrogen dioxide -> nitrous oxide)

norte₂o₅+H₂O -> 2HNO₃

(nitrous oxide + water -> nitric acid)

2)SMOG:Smog is a mixture of fog and smoke. Natural fog mainly contains nitrogen oxides, which come from domestic fires, industrial furnaces, power plants and internal combustion engines, power plants and internal combustion engines that use gasoline or diesel fuel. One of the most important smogs is photochemical smog, formed when sunlight reacts with a volatile organic compound in the atmosphere. Photochemical smog occurs mainly in summer. The main reaction that takes place is the decomposition of NO₂in the presence of ultraviolet light. The reaction produces oxidized hydrocarbons, i. H. peroxyl acetyl nitrate (PAN),Formaldehydeozone, aldehyde, acrolein, etc. These oxidized hydrocarbons and ozone form photochemical pollution in the presence of moisture. This contamination causes coughing, irritation of the eyes, lungs, nose, throat. It also causes damage to plants.

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3)Ozone layer depletion:The ozone layer acts like a filter, absorbing harmful ultraviolet radiation from the sun. the concentration ofOzoneit is determined by the ratio of nitrogen oxide (NO) and nitrogen dioxide (NO).₂), during the day the concentration of nitric oxide (NO) and nitrogen dioxide (NO₂) together at this time, the ozone is in a steady state, which is called the “photosteady state”.

Lachgas (N₂O)+ultraviolet radiation -> N₂+O

norte₂O+O -> Nitrous Oxide (NO)+NO

NO + Ozono (O₃) -> Nitrogen dioxide (NO₂)+O₂

This relationship between ozone and NOx is known as the "Leighton relationship".

Nitrous oxide emissions from high-flying supersonic aircraft also contribute to ozone depletion.

NO+ClO ->Cl+NO₂

(nitrogen monoxide+chlorine monoxide -> chlorine+nitrogen dioxide)

Cl+O₃->ClO+O₂

(chlorine ozone -> chlorine oxygen monoxide)

NO+O₃-> NO₂+O₂

(nitrogen monoxide+ozone->nitrogen dioxide+oxygen)

4)Others :

• Nitric oxide (NO) is not serious, but it does not dissolve easily in water and is therefore not readily absorbed by lung tissue. In the presence of sunlight, nitric oxide can react with oxygen to form nitrogen dioxide. NO causes some health problems, causes hypotension. It causes migraines and damages brain cells that lead to neurodegenerative diseases like Parkinson's, Alzheimer's, Huntington's disease, and amyotrophic lateral sclerosis.
• Nitrogen dioxide (NO₂) is a reddish-brown poisonous gas with an unpleasant odor, causes respiratory diseases, elevated levels of NO₂causes eye irritation and constipation. It also reduced the function of the lungs. High levels of nitrogen dioxide cause asthma, and also breathing high levels of nitrogen dioxide can cause rapid burns, inflammation of the tissues in the throat and airways, decreased oxygen supply to body tissues, and in some cases sometimes death. Hotspots of the northern hemisphere, the presence of NE₂it is very high, in winter the people of this region used combustion plants to heat their houses, so NO₂it stays in the air longer during this period, so nitrogen dioxide is less visible in winter₂Harmful to vegetation as it is toxic in short-term concentrations and reduces plant growth. NO₂reduce the pH of soil and water. Another effect of NO₂As it fades and stains furniture and fabrics, it also reduces visibility.
• Lachgas (N₂O) once inhaled, combined with oxygen it gives a sensation in the body that helps you feel relaxed and comfortable, which is why it is also known as laughing gas. It effectively copes with pain and anxiety, therefore it is used during dental treatment. It is odorless and colorless.₂O is a greenhouse gas, it stays in the atmosphere for a long time compared to carbon dioxide and increases the greenhouse effect. atmospheric N₂The O concentration increased due to human activities. It is more harmful to the climate than carbon dioxide, that is, it is 300 times more harmful thancarbon dioxide. The use of nitrogen-based fertilizers and the burning of fuel and wood are the main sources of N.₂O. Compared to other greenhouse gases, nitrous oxide absorbs radiation and traps heat in the atmosphere, existing on average for 114 years. No₂Stimulates seed germination, affects plant life. Nitrous oxide can react with ozone to become a secondary pollutant called peroxyacetyl nitrate (PAN), which irritates the eyes.

The SofiaNOx Protocol was signed by 23 countries in 1998 and entered into force in 1991. This protocol requires NOx emissions to be frozen in 1987. Reduce the amount of nitrogen oxides by using low-nitrogen fuels and also change combustion conditions to produce less NOx. The “selective catalytic reaction” converts NOx to diatomic nitrogen using a catalyst, so it is a reduction process to remove NOx.