What is Nitrogen? Explain the Uses of Nitrogen and Nitrogen Cycle

Posted on May 5th, 2021
What is Nitrogen? Explain the Uses of Nitrogen and Nitrogen Cycle

What is Nitrogen? Explain the Uses of Nitrogen and Nitrogen Cycle

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What is Nitrogen?

Between carbon and oxygen, the 7th element of the periodic table is Nitrogen. The element Nitrogen has atomic number 7 and the symbol “N”. Among the elements of group 15, Nitrogen is the lightest element. It has no color, mostly diatomic non-metal gas along with odorless and colorless in nature. It’s an important part of amino acids. Nitrogen gas makes up about 80% of the Earth’s atmosphere. Any of the compounds are trivalent and it has five electrons in its outer shell. It is found in all living tissues. It is a necessary component of life since it is a component of DNA and part of a genetic code. It can be present in soil and water as nitrates and nitrites. All of these compounds are related and are part of the nitrogen cycle. Industrial companies release a lot of nitrogen, which increases the nitrite and nitrate content in the ground and water as a result of nitrogen cycle reactions.


Commercial production of Nitrogen

Nitrogen is primarily produced commercially by fractional distillation of liquefied air. Nitrogen’s boiling temperature is −195.8 °C (−320.4 °F) and is about 13 °C (−23 °F) lower than that of oxygen, and is therefore left behind. Nitrogen may also be generated in large quantities by burning biomass or hydrocarbons in the air and then removing the resultant carbon dioxide and water from the residual nitrogen. Pure nitrogen is produced on a small scale by heating barium azide, Ba(N3)2. Heating ammonium nitrate (NH4NO2) solutions, and oxidation of ammonia by bromine water, and oxidation of ammonia by hot cupric oxide are all laboratory reactions that yield nitrogen.

NH4 +  + NO2 —> N2 + 2H2O

8NH3   + 3Br2  —> N2 + 6NH4 + 6Br

2NH3   + 3CuO  —> N2 + 3H2O + 3Cu


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Uses of Nitrogen

To manufacture products for daily use, Nitrogen is used in several industries. Let us discuss some uses of Nitrogen gas.

  • Preservation of Food

Nitrogen gas is used to aid in food storage by avoiding oxidative damage that leads to spoilage. To aid in the preservation of processed food, a man-made atmosphere is created using nitrogen gas and carbon dioxide.

  • Pharmaceuticals Industry

Nitrogen gas is used in every major prescription medicine and is widely used in the pharmaceutical industry, including antibiotics and anesthetics.

  • Electronics Manufacturing

Many people will be surprised to hear that nitrogen is used in the electronics industry. During the manufacturing process, nitrogen is used to create an inert atmosphere to avoid oxidation, which could lead to electrical loss.

  • Stainless Steel Manufacturing

During the stainless steel manufacturing process, nitrogen is used to eliminate impurities. One of the best characteristics of stainless steel is its resistance to corrosion, which is due to the addition of nitrogen gas during the manufacturing process.


Nitrogen Cycle

Nitrogen Cycle
Nitrogen Cycle

The nitrogen cycle is a cyclical mechanism in which nitrogen flows through both living and non-living things, including the atmosphere, soil, water, plants, animals, and bacteria. Nitrogen must change forms in order to migrate through the various stages of the cycle. Nitrogen exists as a gas (N2) in the atmosphere, but in the soils, it exists as nitrogen dioxide, NO2, and nitrogen oxide, NO, and when used as a fertilizer, it can be present in other forms, such as ammonia, NH3, which can be converted further into a new fertilizer, ammonium nitrate, (NH4NO3).

Fixation or volatilization, mineralization, nitrification, immobilization, and de-nitrification are the five stages of the nitrogen cycle that we can go through in sequence. Since microbes in the soil convert nitrogen gas (N2) into what is called volatile ammonia (NH3), so the fixation process is known as volatilization. Leaching is the process by which such sources of nitrogen (such as nitrate, or NO3) dissolve in water and spill out of the soil, thereby polluting waterways.


Stage 1: Nitrogen Fixation

Nitrogen moves from the atmosphere into the soil at this time. The Earth’s atmosphere holds a massive reservoir of nitrogen gas (N2). However, since plants cannot use the gaseous process directly without transformation, this nitrogen is “unavailable” to them. N2 must be converted before it can be used by plants, a process is known as nitrogen fixation. Fixation is a process by which nitrogen in the atmosphere is converted into ways that plants can consume from their root systems.

When lightning strikes supply the energy required for N2 to react with oxygen, releasing nitrogen oxide, NO, and nitrogen dioxide, NO2. These nitrogen forms are then washed into soils by rain or snow. Nitrogen may also be fixed during the fertilizer production process. Under high heat and pressure, atmospheric nitrogen and hydrogen are combined to create ammonia (NH3), which can then be extracted further, to produce ammonium nitrate (NH4NO3), a form of nitrogen, which can be added to soils and further used by plants.

The majority of nitrogen fixation occurs naturally in the soil by bacteria. The bacteria obtain energy from photosynthesis and, in exchange, fix nitrogen into a form needed by the plant. The fixed nitrogen is then transported to other parts of the plant and used to form plant tissues, allowing the plant to expand. Other bacteria can fix nitrogen without this symbiotic relationship and can survive in soils or water. These bacteria can also generate nitrogen in forms that organisms can use.


Stage 2: Mineralization

This stage occurs in the soil. Nitrogen is converted from organic ingredients like fertilizer or plant materials to an inorganic nitrogen supply that plants may use. As the plant’s nutrients are exhausted, it dies and decomposes. This becomes crucial in the second phase of the nitrogen cycle. Mineralization happens as microbes act on organic matter, such as food waste or decomposing plant or animal matter, and begin to convert it into a nitrogen supply for plants. Except for legumes (plants with seed pods that break in two, such as lentils, beans, peas or peanuts), all plants in cultivation get their nitrogen from the soil. As previously mentioned, legumes obtain nitrogen by fixation in their root nodules.

Ammonia, NH3, is the first source of nitrogen produced during the mineralization process. After that, NH3 in the soil then reacts with water to form ammonium, NH4. This ammonium is stored in the soils and is eligible for use by plants that do not receive nitrogen from the symbiotic nitrogen-fixing relationship.


Stage 3: Nitrification

Nitrification, the 3rd stage, also occurs in soils. During nitrification, ammonia in mineralized soils is converted into nitrites, NO2, and nitrates, NO3. Nitrates are used for the plants and also for the animals that consume plants. Any soil bacteria can convert ammonia to nitrates. While nitrite is not specifically usable by plants and animals, other bacteria may convert nitrites into nitrates, which are usable by plants and animals. This reaction provides energy to the bacteria involved in the process. The bacteria that we are discussing about are known as Nitrosomonas and Nitrobacter. Nitrobacter converts nitrites into nitrates, while Nitrosomonas converts ammonia to nitrites. Both types of bacteria can act the only function in the presence of oxygen, O2. The process of nitrification is essential to plants because it generates a surplus of available nitrogen that can be absorbed by the plants through their root system.


Stage 4: Immobilization

Immobilization, also known as the reversal of mineralization, is the 4th stage of the nitrogen cycle. These two processes work together to regulate the amount of nitrogen in soils. Microorganisms in the soil, including plants, require nitrogen as an energy source. When the residues of decomposing plants do not contain enough nitrogen, these soil microorganisms draw nitrogen from the soil. When microorganisms consume ammonium (NH4+) and nitrate (NO3), these nitrogen forms are no longer available to the plants, resulting in nitrogen shortage, or a loss of nitrogen. As a result, nitrogen is bound in microorganisms due to immobilization. Immobilization, on the other hand, is important because it helps regulate and balance the amount of nitrogen in the soils by binding up, or immobilizing, the nitrogen in microorganisms.


Stage 5: De-nitrification

Nitrogen returns to the atmosphere in the 5th stage of the nitrogen cycle when nitrates are converted to atmospheric nitrogen (N2) by bacteria in a mechanism known as de-nitrification. This causes an eventual depletion of nitrogen from soils as the gaseous form of nitrogen passes into the atmosphere, bringing us back to where we started.


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