Information about preparation and uses of nitrogen

Nitrogen is a naturally occurring element that is required for both plant and animal growth and reproduction. It can be found in amino acids, which are the building blocks of proteins, nucleic acids, which are the hereditary material and life’s blueprint for all cells, and a variety of other organic and inorganic chemicals. Furthermore, nitrogen makes up roughly 80% of the Earth’s atmosphere. 

Occurrence of nitrogen

Nitrogen is the most common pure element on the earth. Despite this, it is rare in the Earth’s crust, with only 19 parts per million. Nitrogen molecules are regularly exchanged between the atmosphere and living things. The first step is to fix nitrogen into a plant-useable form, which is commonly ammonia. Although lightning strikes produce nitrogen oxides, the majority of nitrogen fixation is done by diazotrophic bacteria that use nitrogenases enzymes. When ammonia is taken up by plants, it is used to make proteins. Animals digest the nitrogen molecules in these plants, which they use to make proteins and emit nitrogen-bearing faeces. Finally, through bacterial and environmental oxidation and denitrification, these organisms die and decompose, exposing free dinitrogen to the atmosphere. 

Atomic number of nitrogen

The charge number of an atomic nucleus is represented by the atomic number or nuclear charge number (sign Z) of a chemical element. This is equivalent to the proton number (np), or the number of protons found in the nucleus of every atom of that element, for conventional nuclei. 

The atomic number of nitrogen is 7, which means each nitrogen atom has seven protons. 

Mass number of nitrogen

The total number of protons and neutrons in an element determines its mass number. 

Mass number = number of protons + number of neutrons 

Although nitrogen’s mass number is 14, its real mass is larger than 14 since mass number refers to the number of protons and neutrons in a nucleus. 

Molecular weight of nitrogen

The mass of one molecule of a material is expressed in atomic mass units as molecular mass (molecular weight) (μ). 

Nitrogen is a chemical element with the symbol N, atomic number 7, and atomic mass 14.00674 as well as the symbol N.

The mass of the N2 molecule in nitrogen is 

N2 = 14.01 + 14.01

N2 = 28.02

As a result, a nitrogen molecule has a molecular mass of 28μ. 

Properties of nitrogen

Physical properties

1. It’s an odourless, tasteless, and colourless gas. 
2. It is non-poisonous, yet animals perish from a lack of oxygen in a nitrogen-rich environment. 
3. It has a very low water solubility (23.2 cm3 per litre of water at and pressure). 
4. 63.2K and 77.2K are the melting and boiling points, respectively. 

Chemical properties

1. At normal temperatures, N2 is practically non-reactive. It doesn’t burn and doesn’t enable combustion. The chemical inertness of N2 at normal temperatures is related to the molecule’s strong stability. 
2. The two nitrogen atoms in a molecule of N2 are connected by a triple bond. The bond enthalpy (the amount of heat energy required to break a chemical bond) of the triple bond is extremely high. 
3. N2 is almost unreactive with most reagents due to its extremely high bond dissociation enthalpy. 
4. It does, however, interact with some metals and non-metals at high temperatures to generate nitrides, which are ionic and covalent compounds. 

Electronic configuration of nitrogen

The arrangement of an element’s electrons in its atomic orbitals is known as its electronic configuration. Nitrogen has an atomic number of 7 and an electronic configuration of 1s²2s²2p³.

The 1s orbital will get the first two electrons. Because the 1s orbital can only hold two electrons, N’s next two electrons are placed in the 2s orbital. The three remaining electrons will be placed in the 2p orbital. As a result, the electron configuration of the N atom will be 1s²2s²2p³. 

Preparation of nitrogen

Commercially, nitrogen is obtained by liquefaction and fractional distillation of air. This process consists of two basic steps: 

Step 1: High pressure between 100 and 200 atmospheres is used to reduce air to liquid air. The compressed air is then expanded by passing it through a fine jet. This procedure is performed multiple times, resulting in liquid air production.

Step 2: Fractional distillation is performed on the resulting liquid. Dinitrogen has a lower boiling point than liquid oxygen, therefore it separates from it, leaving liquid oxygen behind. The impure liquid serves as a source of nitrogen.

Dinitrogen is produced in the laboratory by reacting an aqueous solution of ammonium chloride with sodium nitrite. 

NH₄Cl(aq) + NaNO₂(aq) → N₂(g)+ 2H₂O(l) + NaCl(aq) 

Impurities such as NO and HNO3 are present in the products, which can be eliminated by thermal decomposition of ammonium dichromate. Passing the gaseous mixture via sulphuric acid containing potassium dichromate is another way to eliminate contaminants.

(NH₄)₂Cr₂O₇  → N₂+ 4H₂O+ Cr₂O₃ 

Pure nitrogen is formed through the decomposition of sodium or barium azide in the presence of high temperature. 

Uses of nitrogen

The chemical sector relies on nitrogen. Fertilisers, nitric acid, nylon, colours, and explosives are all made from it. Nitrogen must first be reacted with hydrogen to form ammonia before these products may be made. The Haber process is used to do this. Every year, 150 million tonnes of ammonia are produced in this manner.

Nitrogen gas is also utilised to create a non-reactive environment. It’s used to preserve foods in this fashion, as well as in the electronics industry to make transistors and diodes. In the annealing of stainless steel and other steel mill products, large amounts of nitrogen are needed. Annealing is a thermal treatment that makes working with steel easier.

As a refrigerant, liquid nitrogen is frequently used. It is used in medical research and reproductive technologies to store sperm, eggs, and other cells. It’s also used to quickly freeze foods, keeping moisture, colour, flavour, and texture intact. 

Biology role of nitrogen

The ‘nitrogen cycle’ is a natural process in which nitrogen is cycled by living organisms. It’s taken up as nitrates by green plants and algae, and it’s used to make the bases that make up DNA, RNA, and all amino acids. Proteins are made up of amino acids, which are the building components.

Nitrogen is obtained by animals through digesting other living things. Proteins and DNA are digested into their constituent bases and amino acids, which they reconstruct for their own use.

Microbes in the soil break down nitrogen molecules into nitrates, which plants can utilise again. Nitrogen-fixing bacteria that ‘fix’ nitrogen straight from the atmosphere also replenish the nitrate supply. 

Conclusion

Nitrogen is one of the most essential nutrients for the survival of all living things. Although nitrogen is abundant in the atmosphere as dinitrogen gas (N₂), most species cannot use it in this form, making it a rare resource and limiting primary productivity in many ecosystems. Nitrogen becomes available to primary producers, such as plants, only after it has been transformed from dinitrogen gas to ammonia (NH₃).