Introduction to Nitrogen Gas
Nitrogen makes up around four-fifths of the Earth's atmosphere, and it was isolated and identified as a distinct substance during early air research. Carl Wilhelm Scheele, a Swedish chemist, demonstrated in 1772 that air is a mixture of two gases, one of which he dubbed "fire air" because it promoted combustion, and the other "foul air" because it remained after the "fire air" had been consumed. Of course, the "fire air" was oxygen, while the "foul air" was nitrogen.
What is Nitrogen?
Nitrogen gas is a colourless, odourless gas that makes up around four-fifths of the atmosphere's volume and is found in mixed form in animal and vegetable cells, particularly proteins. Nitrogen is the member of the 15th group of the modern periodic table. Some basic information about Nitrogen are as follows-
The symbol of Nitrogen is N. Nitrogen is found as Nitrogen gas in nature and the symbol of nitrogen gas is N2.
Nitrogen is the seventh element in the periodic table, located between carbon and oxygen.
Electronic configuration of nitrogen is \[\left [He \right]\] 2s22p3.
It's a crucial component of amino acids.
Nitrogen gas makes up around 80% of the Earth's atmosphere.
It is predominantly diatomic non-metal gas, which is odourless and colourless in nature.
Most of its compounds are trivalent because its outer shell has five electrons.
It can be found in all living tissues. It is a necessary component of life because it is a component of DNA and a part of the genetic code.
It can be found in soil and water as nitrates and nitrites.
All of these elements are linked and part of the nitrogen cycle. As a result of reactions in the nitrogen cycle, industrial enterprises emit a lot of nitrogen, which increases the amount of nitrite and nitrate in the ground and water.
Nitrogen as Nitrogen Gas
As we had seen the electronic configuration of nitrogen gas in the previous section, we can say that nitrogen has 3 electrons in its outermost orbit. The outermost orbit is p and it requires 6 electrons to fill completely. Now when we see that the outer p-orbit is half-filled that is comparatively stable than other configurations. Due to this half-filled configuration, nitrogen has a valency of 3. So it can accept three electrons. That’s why in nature nitrogen is found as nitrogen gas as two nitrogen atoms come together to form a molecule that is more stable than an atom. Both nitrogen atoms contribute their 3 outer shell electrons to form covalent bonds. A triple bond binds both nitrogen atoms as a molecule of nitrogen gas.
Nitrogen Formula
Nitrogen is commonly found as nitrogen gas. So nitrogen gas formula is actually the nitrogen formula. The formula of nitrogen is N2. The atomic structure of nitrogen is shown below.
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Properties of Nitrogen
We are discussing some properties of nitrogen here.
With an electronegativity 3.04, nitrogen is a nonmetal.
Nitrogen has a molar mass of 28.02 g/mol.
The molecular weight of nitrogen gas is 28.02 u.
Because its outer shell comprises five electrons, it is trivalent in most compounds.
One of the strongest known triple bonds is found in molecular nitrogen (N2).
The difficulty of turning N2 into other compounds as a result of this, as well as the ease (and accompanying high energy release) of converting nitrogen compounds into elemental N2, has dominated nitrogen's function in both nature and human economic activity.
The Melting point of Nitrogen is 63.2 K.
The Boiling point of Nitrogen is 77.355 K.
The Density of Nitrogen is 0.001145 g/cm3.
As nitrogen is a colourless gas so there is no colour of nitrogen gas.
Uses of Nitrogen
Nitrogen is part of proteins and it makes it the most useful substance needed for the growth of plants. Nitrogen has a wide range of uses. The importance of nitrogen for the growth of plants makes it more important in the agriculture industry. Some important uses of nitrogen are as follows-
It's used to make ammonia, then to make nitric acid, which is then utilised as a fertiliser.
Potassium nitrate, ammonium nitrate, and nitric acid are all examples of nitric acid salts. Nitro glycerine and other nitrated organic compounds are common explosives.
Liquid nitrogen is used as a refrigerant in the transportation and freezing of food. Liquid nitrogen is also used to preserve bodies and reproductive cells, as well as to keep biological samples stable.
Nitrogen is found in all living tissue and comprises approximately 78 per cent of the Earth's atmosphere. Because nitrogen is a component of DNA and hence a part of the genetic code, it is an essential component of life.
Soil contains a lot of nitrogen molecules. Nitrogen can be found in the form of nitrates and nitrites in both water and soil. These molecules are all part of the nitrogen cycle, which is linked to the carbon cycle.
Laboratory Method for Preparation of Nitrogen Gas
N2 is made in the lab by heating an aqueous solution of ammonium chloride and sodium nitrite in water.
NaCl(aq) + NaNO2(aq) → NaCl(aq) + 2H2O(l) + N2(g)
This reaction also produces small amounts of nitric oxide and nitric acid. Bypassing the developed gas through an aqueous sulphuric acid solution containing potassium dichromate, the N2 is purified.
Nitrogen Cycle
A cycle is a set of events or steps that repeat itself on a regular basis. Nitrogen goes from the soil to plants, then to animals, and eventually back to the soil via the nitrogen cycle. It can be reused by another plant after it returns to the soil from a decaying plant.
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The five major steps of the nitrogen cycle are as follows-
1. Nitrogen fixation
2. Nitrification
3. Denitrification
4. Nitrogen assimilation
5. Ammonification.
FAQs on Nitrogen Gas
1. What is nitrogen gas and what is its chemical formula?
Nitrogen gas, also known as dinitrogen, is a chemical element that is a colourless, odourless, and non-toxic gas. It constitutes about 78% of the Earth's atmosphere. In its elemental gas form, two nitrogen atoms bind together with a strong triple bond, giving it the chemical formula N₂. This diatomic structure makes it very stable.
2. What are the key physical and chemical properties of nitrogen gas?
The properties of nitrogen gas are largely dictated by its strong N≡N triple bond. Key properties include:
- Physical Properties: It is a colourless, odourless, and tasteless gas. It has a low boiling point (77.36 K) and melting point (63.15 K) and is only slightly soluble in water.
- Chemical Properties: Nitrogen gas is relatively inert and unreactive at room temperature due to the very high bond enthalpy of its triple bond. It will only react with other elements under high temperatures and pressures, such as with hydrogen in the Haber process to form ammonia.
3. Why is nitrogen gas (N₂) so stable and relatively inert?
The exceptional stability and relative inertness of nitrogen gas stem from the unique bond between its two atoms. The N₂ molecule features a triple covalent bond (N≡N). This bond has a very high bond dissociation enthalpy (941.4 kJ/mol), meaning a large amount of energy is required to break it apart. This strong bond makes the molecule very stable and, consequently, unreactive under normal conditions, a key concept in chemistry.
4. How is pure nitrogen gas prepared in a laboratory as per the NCERT syllabus?
In a laboratory setting, nitrogen gas is typically prepared by reacting an aqueous solution of ammonium chloride (NH₄Cl) with sodium nitrite (NaNO₂). The reaction is:
NH₄Cl(aq) + NaNO₂(aq) → N₂(g) + 2H₂O(l) + NaCl(aq).
For producing very high purity nitrogen, the thermal decomposition of sodium azide (NaN₃) or barium azide (Ba(N₃)₂) is the preferred method.
5. What are the most important industrial and biological uses of nitrogen?
Nitrogen is crucial for both industrial processes and life itself.
- Industrial Uses: The primary use is in the Haber process to manufacture ammonia, which is then used to produce fertilisers and nitric acid. It is also used to create an inert atmosphere in food packaging to preserve freshness and in the electronics industry.
- Biological Uses: Nitrogen is a fundamental component of all living organisms. It is a key part of amino acids (the building blocks of proteins) and nucleic acids (DNA and RNA), making it essential for growth and heredity.
6. How is liquid nitrogen different from nitrogen gas, and what are its main applications?
Liquid nitrogen is simply nitrogen gas cooled to a cryogenic temperature (below its boiling point of 77.36 K or -196°C). While chemically identical (both are N₂), their physical states and applications differ greatly. Nitrogen gas is used for its inertness, while liquid nitrogen is used for its intense cold. Its main applications include being a cryogenic refrigerant for freezing and transporting food products, cryopreservation of biological samples like blood and reproductive cells, and in dermatology for cryotherapy.
7. What is the importance of nitrogen gas in the Earth's nitrogen cycle?
Nitrogen gas in the atmosphere acts as the largest reservoir of elemental nitrogen. However, most organisms cannot use it directly. The nitrogen cycle's primary importance is to convert this unusable atmospheric N₂ into usable forms. This first step, called nitrogen fixation, is performed by certain bacteria that convert N₂ into ammonia (NH₃). This ammonia then enters the ecosystem and is used by plants, beginning the cycle that makes nitrogen available to all life.
8. How is nitrogen gas (N₂) fundamentally different from nitrogen dioxide (NO₂)?
While both are compounds of nitrogen, they have vastly different properties. The key difference lies in their chemical structure and reactivity. Nitrogen gas (N₂) is a stable, diatomic molecule with a strong triple bond, making it colourless and largely inert. In contrast, nitrogen dioxide (NO₂) is a highly reactive, reddish-brown toxic gas with weaker bonds. N₂ makes up 78% of our air and is non-toxic, whereas NO₂ is a major air pollutant.
