Dinitrogen - Preparation, Properties And Uses

Edited By Shivani Poonia | Updated on Jul 02, 2025 06:40 PM IST

The dinitrogen comprises about 78% of the atmosphere here on Earth; hence, it is a rather very fundamental component in the Nitrogen cycle necessary for life on Earth. Abundant as it is, owing to its being an inert substance, until today it still eludes service—putting it into service, that is—without the use of inventive new methods of preparation and application.

This Story also Contains

Preparation and Properties of Dinitrogen
Some Solved Examples
Summary

Dinitrogen

Preparation and Properties of Dinitrogen

Normally, dinitrogen is prepared by the fractional distillation of liquid air; this is the separation of nitrogen from other atmospheric gases, such as oxygen and argon. Another common way this can be done is through the decomposition of sodium or barium azide, NAN₃ or Ba(N₃)₂, respectively, which finally yields pure nitrogen gas. Dinitrogen is colorless, odorless, and tasteless, characterized by its high stability due to the triple bond between the two nitrogen atoms. This in turn indeed requires high energy to break the bond, making dinitrogen quite unreactive at room temperature. At high temperatures and pressures or in the presence of catalysts dinitrogen will react with other elements and make some very important compounds, for example, ammonia NH₃.

Preparation

Dinitrogen is produced commercially by the liquefaction and fractional distillation of air. Liquid dinitrogen (b.p. 77.2 K) distils out first leaving behind liquid oxygen (b.p. 90 K). In the laboratory, dinitrogen is prepared by treating an aqueous solution of ammonium chloride with sodium nitrite.

Small amounts of NO and HNO₃ are also formed in this reaction; these impurities can be removed by passing the gas through aqueous sulphuric acid containing potassium dichromate. It can also be obtained by the thermal decomposition of ammonium dichromate.

Very pure nitrogen can be obtained by the thermal decomposition of sodium or barium azide.

Properties

Dinitrogen is a colorless, odorless, tasteless, and non-toxic gas. Nitrogen atom has two stable isotopes: ¹⁴N and ¹⁵N. It has very low solubility in water (23.2 cm³ per liter of water at 273 K and 1 bar pressure) and low freezing and boiling points. Dinitrogen is rather inert at room temperature because of the high bond enthalpy of N≡N bond. Reactivity, however, increases rapidly with rise in temperature. At higher temperatures, it directly combines with some metals to form predominantly ionic nitrides and with non-metals, covalent nitrides. A few typical reactions are:

Uses

The main use of dinitrogen is in the manufacture of ammonia and other industrial chemicals containing nitrogen, (e.g., calcium cyanamide).
It also finds use where an inert atmosphere is required (e.g., in the iron and steel industry, inert diluent for reactive chemicals).
Liquid dinitrogen is used as a refrigerant to preserve biological materials and food items, and in cryosurgery.

Some Solved Examples

Example: 1 On heating compound (A) gives a gas (B) which is a constituent of air. This gas when treated with H₂ in the presence of a catalyst gives another gas (C) which is basic in nature. (A) should not be :

1)NaN₃

2) (correct)Pb(NO₃)₂

3)(NH₄)₂Cr₂O₇

4)NH₄NO₂

Solution

Basic gas (C) must be ammonia (NH₃). It means (B) gas should be N₂ which is formed by the heating of compound (A).

(1) (NH₄)₂Cr₂O₇→ΔN₂↑+Cr₂O₃+4H₂O↑
(2) Pb(NO₃)₂→ΔPbO+2NO₂↑+12O₂↑
(3) 2NaN₃→Δ2Na+3N₂↑
(4) NH₄NO₂→ΔN₂↑+2H₂O↑

Pb(NO₃)₂ is not giving Nitrogen gas.

Example: 2 The correct statement with respect to dinitrogen:

1)N₂ is paramagnetic in nature.

2)It can combine with dioxygen at 25∘C

3) (correct)It can be used as an inert diluent for reactive chemicals.

4)Liquid dinitrogen is not used in cryosurgery.

Solution

As we have learnt,

Dinitrogen is a very stable molecule with a very high N≡N bond energy and is practically inert at room temperature.

Due to its almost inert nature, Nitrogen is used as an inert diluent for reactive chemicals.

Hence, the answer is the option (3).

Summary

Dinitrogen is considered by many to be a forgotten molecule; however, it truly is one of immense importance. Dinitrogen impacts nearly all aspects of life and industry. Elucidation of the properties of a molecule as complex as this one details not only scientific but also practical implications for agriculture, medicine, electronics, and the science of the environment.

Frequently Asked Questions (FAQs)

1. What is dinitrogen and why is it important?

Dinitrogen (N₂) is a colorless, odorless gas that makes up about 78% of Earth's atmosphere. It's crucial for life as it's a key component of amino acids, proteins, and nucleic acids. In industry, it's used to produce fertilizers, explosives, and various chemicals.

2. How is the triple bond in dinitrogen formed?

The triple bond in dinitrogen is formed by the sharing of three electron pairs between two nitrogen atoms. This consists of one sigma (σ) bond and two pi (π) bonds, resulting in an extremely strong and stable bond.

3. Why is dinitrogen considered inert at room temperature?

Dinitrogen is considered inert at room temperature due to its strong triple bond. This bond requires a large amount of energy to break, making it unreactive under normal conditions. This property is why nitrogen gas is often used in inert atmospheres.

4. What is the Haber process and how does it relate to dinitrogen?

The Haber process is an industrial method for producing ammonia (NH₃) from dinitrogen and hydrogen. It involves reacting N₂ with H₂ at high temperature and pressure in the presence of an iron catalyst. This process is crucial for fertilizer production.

5. How does lightning contribute to the nitrogen cycle?

Lightning provides the high energy needed to break the strong triple bond in dinitrogen. This allows atmospheric nitrogen to combine with oxygen, forming nitrogen oxides. These compounds can then dissolve in rainwater, making nitrogen available to plants in the form of nitrates.

6. What is the importance of dinitrogen in the food packaging industry?

In food packaging, dinitrogen is used to create an inert atmosphere that prevents oxidation and microbial growth. This process, known as modified atmosphere packaging (MAP), extends the shelf life of foods by displacing oxygen, which can cause spoilage or support bacterial growth.

7. What is the role of dinitrogen in the production of semiconductors?

In semiconductor manufacturing, high-purity nitrogen is used to create inert atmospheres during various processes. It helps prevent unwanted reactions, oxidation, and contamination. Liquid nitrogen is also used for cooling in certain stages of semiconductor production.

8. What is the significance of dinitrogen in the Earth's early atmosphere?

Dinitrogen likely played a crucial role in the Earth's early atmosphere. It's believed that the primitive atmosphere was rich in N₂, CO₂, and water vapor. The stability of N₂ allowed it to persist while other gases reacted or escaped, contributing to the current composition of our atmosphere.

9. How does dinitrogen contribute to the greenhouse effect?

Dinitrogen itself is not a greenhouse gas and doesn't directly contribute to the greenhouse effect. However, some nitrogen compounds like nitrous oxide (N₂O), which can form from N₂ under certain conditions, are potent greenhouse gases.

10. What is the role of dinitrogen in biological nitrogen fixation?

In biological nitrogen fixation, certain bacteria (like Rhizobium in legume root nodules) can break the triple bond of dinitrogen and convert it into ammonia. This process uses the enzyme nitrogenase and requires significant energy input. It's a crucial part of the nitrogen cycle, making atmospheric nitrogen available to plants.

11. Why is dinitrogen used in some types of welding?

Dinitrogen is used in some welding processes as a shielding gas. It helps protect the weld area from atmospheric gases that could cause oxidation or other unwanted reactions. However, it's often used in combination with other gases like argon, as pure nitrogen can cause brittleness in some metals.

12. What is the role of dinitrogen in the formation of the aurora borealis?

Dinitrogen plays a role in creating the colors of the aurora borealis (northern lights). When charged particles from the sun collide with nitrogen molecules in the upper atmosphere, they can excite the nitrogen. As these excited molecules return to their ground state, they emit light, contributing to the characteristic blue and purple colors of the aurora.

13. What is the importance of isotopes of nitrogen in studying the nitrogen cycle?

Nitrogen has two stable isotopes, ¹⁴N and ¹⁵N. The ratio of these isotopes in different compounds can be used as a tracer to study the nitrogen cycle. For example, measuring the ¹⁵N/¹⁴N ratio in plants, soil, and water can provide information about nitrogen sources, transformations, and movement in ecosystems.

14. How does the presence of dinitrogen affect combustion processes?

The presence of dinitrogen in air affects combustion processes by acting as a heat sink. It absorbs some of the heat produced during combustion without participating in the reaction, thereby moderating the temperature. This can affect flame temperature and combustion efficiency in various applications, from internal combustion engines to industrial furnaces.

15. What is the importance of understanding dinitrogen's behavior at high temperatures for atmospheric reentry of spacecraft?

Understanding dinitrogen's behavior at high temperatures is crucial for designing heat shields for spacecraft reentering Earth's atmosphere. At the extreme temperatures encountered during reentry, nitrogen molecules can dissociate and then recombine, releasing large amounts of heat. This process contributes significantly to the thermal load on the spacecraft.

16. What is the role of dinitrogen in the production of ammonia through biological processes?

In biological processes, certain microorganisms can convert dinitrogen into ammonia through nitrogen fixation. This is carried out by nitrogenase enzymes, which can break the triple bond of N₂ at ambient temperatures and pressures - a feat that requires extreme conditions in industrial processes. Understanding this biological process is crucial for developing more efficient artificial nitrogen fixation methods.

17. How does the quantum mechanical description of dinitrogen explain its stability?

The quantum mechanical description of dinitrogen involves molecular orbital theory. The triple bond consists of one sigma bond and two pi bonds, formed by the overlap of atomic orbitals. This arrangement results in a large energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), contributing to the molecule's stability and low reactivity.

18. What is nitrogen fixation and why is it important?

Nitrogen fixation is the process of converting atmospheric nitrogen (N₂) into biologically usable forms like ammonia. It's crucial because most organisms can't use dinitrogen directly. Nitrogen fixation can occur naturally (by lightning or certain bacteria) or artificially (through industrial processes).

19. How does the boiling point of dinitrogen compare to oxygen, and why?

Dinitrogen has a lower boiling point (-195.8°C) than oxygen (-183°C). This is because N₂ molecules have weaker intermolecular forces (van der Waals) compared to O₂ molecules, which have slightly stronger dipole-induced dipole interactions due to oxygen's higher electronegativity.

20. Why is liquid nitrogen used for cryogenic applications?

Liquid nitrogen is used for cryogenic applications because of its extremely low boiling point (-195.8°C). This allows it to rapidly cool materials to very low temperatures. It's also relatively inert, abundant, and cost-effective compared to other cryogenic liquids.

21. How does the reactivity of dinitrogen change with temperature?

Dinitrogen's reactivity increases with temperature. At room temperature, it's mostly inert due to its strong triple bond. However, at high temperatures (like those in car engines or lightning strikes), the bond can break, allowing nitrogen to react with other elements.

22. What role does dinitrogen play in the production of fertilizers?

Dinitrogen is a key raw material in fertilizer production. Through the Haber process, it's converted into ammonia, which is then used to make various nitrogen-containing fertilizers like urea and ammonium nitrate. These fertilizers provide essential nitrogen for plant growth.

23. How is dinitrogen commercially prepared?

Dinitrogen is commercially prepared by the fractional distillation of liquid air. As nitrogen has a lower boiling point than oxygen, it can be separated from other components of air. This process involves cooling air until it liquefies, then slowly warming it to separate different gases based on their boiling points.

24. What is the significance of dinitrogen's triple bond in terms of bond energy?

The triple bond in dinitrogen has a very high bond energy (941 kJ/mol), making it one of the strongest bonds known. This high bond energy explains nitrogen's stability and low reactivity at room temperature. Breaking this bond requires significant energy input, which is why nitrogen fixation processes are often energy-intensive.

25. How does dinitrogen behave under high pressure?

Under extremely high pressures (above 1.1 million atmospheres), dinitrogen can transform into a polymeric form called cubic gauche nitrogen. In this state, nitrogen atoms form a network of single bonds instead of triple bonds, dramatically changing its properties and potentially making it a high-energy-density material.

26. Why doesn't dinitrogen support combustion?

Dinitrogen doesn't support combustion because it's non-flammable and doesn't react with most substances at normal temperatures. Its strong triple bond makes it unreactive, so it doesn't provide oxygen or participate in combustion reactions. This property makes nitrogen useful for fire suppression systems.

27. How does the molecular structure of dinitrogen contribute to its properties?

Dinitrogen's linear molecular structure, with its strong triple bond, contributes to its stability, low boiling point, and low reactivity. The symmetry of the molecule results in a non-polar nature, leading to weak intermolecular forces and explaining its gaseous state at room temperature.

28. How does dinitrogen interact with metals at high temperatures?

At high temperatures, some metals can react with dinitrogen to form nitrides. For example, magnesium burns in nitrogen to form magnesium nitride. This reactivity increases with temperature as more energy becomes available to break nitrogen's strong triple bond.

29. How does the electron configuration of nitrogen atoms relate to dinitrogen's properties?

Nitrogen's electron configuration (1s² 2s² 2p³) allows it to form a stable triple bond in dinitrogen. The three unpaired electrons in the 2p orbitals of each nitrogen atom pair up to form one sigma and two pi bonds. This electronic structure contributes to dinitrogen's stability and inertness.

30. Why is dinitrogen used in some light bulbs?

Dinitrogen is used in some light bulbs, particularly in halogen lamps, because it's inert and doesn't react with the filament or other components at high temperatures. It also helps prevent oxidation of the filament, extending the bulb's lifespan.

31. How does the solubility of dinitrogen in water compare to other gases?

Dinitrogen has low solubility in water compared to gases like oxygen or carbon dioxide. This is due to its non-polar nature and weak interactions with water molecules. The low solubility of N₂ in water is important for aquatic ecosystems, as it affects the nitrogen available to aquatic organisms.

32. What is the difference between dinitrogen and dioxygen in terms of paramagnetism?

Dinitrogen is diamagnetic (not attracted to a magnetic field) because all its electrons are paired. In contrast, dioxygen is paramagnetic (attracted to a magnetic field) due to unpaired electrons. This difference arises from their electronic structures and bond orders.

33. How is dinitrogen used in the production of nylon?

Dinitrogen is a crucial raw material in the production of nylon. It's used to make adipic acid and hexamethylenediamine, the two main components of nylon-6,6. The process starts with the production of ammonia from N₂, which is then used in subsequent reactions to form these nylon precursors.

34. How does the density of dinitrogen compare to air, and why is this important?

Dinitrogen has a density slightly lower than air (0.97 times that of air). This property is important in various applications. For example, it allows nitrogen-filled tires to maintain pressure longer than air-filled tires, as nitrogen molecules are less likely to escape through the tire walls.

35. What is the significance of dinitrogen's critical point?

The critical point of dinitrogen (-147°C and 33.5 atm) is the temperature and pressure above which distinct liquid and gas phases of nitrogen do not exist. Understanding this point is crucial for industrial processes involving nitrogen, particularly in cryogenic applications and supercritical fluid extraction.

36. How does dinitrogen behave as a supercritical fluid?

Above its critical point, dinitrogen becomes a supercritical fluid, exhibiting properties between those of a gas and a liquid. In this state, it can diffuse through solids like a gas and dissolve materials like a liquid. This property has potential applications in extraction processes and as a reaction medium.

37. How does the ionization energy of dinitrogen compare to other diatomic molecules?

Dinitrogen has a relatively high ionization energy compared to many other diatomic molecules. This is due to its strong triple bond and the stability of its electron configuration. The high ionization energy contributes to nitrogen's low reactivity and its resistance to forming ions under normal conditions.

38. What is the importance of dinitrogen in the production of nitric acid?

Dinitrogen is a key starting material in the production of nitric acid through the Ostwald process. First, ammonia is produced from N₂ via the Haber process. This ammonia is then oxidized to nitric oxide, which is further oxidized and absorbed in water to form nitric acid. This process is crucial for the chemical industry.

39. How does the presence of dinitrogen affect the properties of Earth's atmosphere?

The high concentration of dinitrogen in Earth's atmosphere contributes to its overall properties. It helps maintain atmospheric pressure, moderates temperature fluctuations due to its heat capacity, and dilutes other gases like oxygen to levels suitable for life. Its inertness also helps stabilize the atmosphere's composition.

40. What role does dinitrogen play in airbags?

Dinitrogen is used to inflate airbags in vehicles. When a collision is detected, a chemical reaction rapidly produces nitrogen gas, which inflates the airbag. Nitrogen is used because it's inert, non-toxic, and can be quickly generated in the required volume.

41. How does the bond length of dinitrogen compare to other diatomic molecules?

The bond length of dinitrogen (1.098 Å) is shorter than that of most other diatomic molecules. This is due to its strong triple bond. For comparison, the O=O double bond in oxygen is 1.21 Å, and the H-H single bond in hydrogen is 0.74 Å. The short bond length contributes to nitrogen's stability and inertness.

42. What is the significance of dinitrogen's quadrupole moment?

Although dinitrogen is a non-polar molecule, it has a quadrupole moment due to the uneven distribution of electron density along its axis. This quadrupole moment, while weak, can lead to slight interactions with other molecules or surfaces, affecting properties like adsorption behavior or solubility in certain solvents.

43. How does dinitrogen interact with transition metal complexes?

Dinitrogen can form complexes with certain transition metals, particularly those in low oxidation states. In these complexes, N₂ can act as a ligand, binding to the metal center. This interaction can weaken the N≡N bond, making it more reactive. Understanding these complexes is important for developing new nitrogen fixation catalysts.

44. How does the heat capacity of dinitrogen affect its uses?

Dinitrogen has a relatively low heat capacity compared to many other gases. This property makes it useful in applications where rapid temperature changes are desired, such as in some heat treatment processes for metals or in certain types of gas springs used in automotive and aerospace industries.

45. How does the polarizability of dinitrogen compare to other gases?

Dinitrogen has a relatively low polarizability compared to many other gases. This is due to its strong triple bond and symmetric structure, which make its electron cloud resistant to distortion. The low polarizability contributes to nitrogen's weak intermolecular forces and its use as an inert gas in many applications.

46. What is the significance of dinitrogen's role in protein denaturing?

Liquid nitrogen, due to its extremely low temperature, can rapidly denature proteins by disrupting their hydrogen bonds and other weak interactions. This property is used in some food preparation techniques (like making ice cream) and in laboratory procedures for preserving biological samples or preparing them for analysis.

47. How does dinitrogen contribute to the formation of nitrides in materials science?

In materials science, dinitrogen can be used to form nitrides - compounds of nitrogen with less electronegative elements. This often requires high temperatures or plasma conditions to break the strong N≡N bond. Nitrides have various applications, from hard coatings (like titanium nitride) to semiconductors (like gallium nitride).