Nitrogen Dioxide: Structure, Formula, Preparation, Properties & Uses

Nitrogen Dioxide is a highly reactive gas in the nitrogen oxides category. It is formed by the combination of nitrogen and oxygen. 

• Nitrogen Dioxide gas is created by natural sources, motor vehicles, and other fuel combustion processes. 
• The formula of the compound is NO₂.
• It is an odourless, acidic, and extremely corrosive gas and can harm our health and the environment. 
• Nitrogen Dioxide is also used as a catalyst in rocket fuels. 
• It completely turns into a reddish-brown gas at high temperatures.
• The colour of the compound changes into a yellow-brown liquid when the compound is compressed.
• The compound is paramagnetic in nature.
• It is used in the production of fertilizers and the synthesis of nitric acid.

Read More: Class 12 Dinitrogen

Key Terms: Nitrogen Dioxide, Oxygen, Nitrogen, Molecule, Atom, Carbon, Element, Compound, Nitric Acid, Paramagnetic

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What is Nitrogen Dioxide?

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Nitrogen dioxide is a nitrogen and oxygen-based chemical compound. It is one of a group of nitrogen oxides. 

• It is also known as Nitrogen oxide or Deutoxide of Nitrogen.
• NO₂ is a byproduct of the industrial synthesis of nitric acid.
• It is used to produce millions of tonnes of fertiliser, which is used in the manufacturing industries.
• Nitrogen Dioxide can be used in the production of dyes and lacquers.
• The compound is part of the NOx family of atmospheric pollutants.
• If inhaled in significant amounts, it can be dangerous.

Read More: Class 12 Group 15 Elements

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Formula of Nitrogen Dioxide 

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Any compound's chemical formula can be either empirical or molecular. A molecular formula describes the number of atoms of each element in one molecule, whereas an empirical formula specifies the simplest whole-number ratio of atoms in a compound. 

• In nitrogen dioxide, the simplest whole number ratio of nitrogen vs oxygen is 1:2. 
• So, the empirical and chemical formula of nitrogen dioxide is NO₂.
• In this, one nitrogen atom combines with two oxygen atoms to form a covalent compound.
• It involves the sharing of electrons between oxygen and nitrogen atoms.
• The boiling point of nitrogen dioxide is 21.15 °C.
• The melting point of nitrogen dioxide is −9.3 °C.

Read More: Electron Gain Enthalpy

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Nitrogen Dioxide Structure

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The electrical structure of nitrogen dioxide is known to be O=N-O. Because nitrogen dioxide possesses an unpaired electron, it behaves like any other odd molecule.

• The monomer NO₂ has an angular structure, with angle = 134 degrees and distance = 1.18 A_o.
• The distance between the nitrogen and oxygen atoms is 119.7 Pico meters.
• At low quantities of nitrogen dioxide, it is a negligibly slow process.
• When combined with dinitrogen tetroxide gas, it tends to exist in an equilibrium state.
• The chemical equation involved in the process is as follows: 2NO₂ ----→ N₂O₄.
• Since nitrogen has one unpaired electron, it's ground electronic state is doublet.

Structure of Nitrogen Dioxide

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Preparation of Nitrogen Dioxide

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Nitrogen dioxide can be prepared by a variety of methods. The following are some of the methods for producing nitrogen dioxide.

• Nitrogen dioxide is usually created when nitric oxide in the air is oxidised by oxygen.
  
                                                                                      2NO + O₂ → 2NO₂
   
• Nitrogen dioxide is produced by most combustion processes that use air as an oxidant. At high temperatures, nitrogen reacts with oxygen to generate nitric oxide.
  
                                                                                          O₂ + N₂ → 2NO
  
                                                                                          2NO + N₂ → 2NO
   
• Some metal nitrates, such as lead nitrate, break thermally and produce nitrites.
  
                                                                            2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂
   
• The action of strong nitric acid on copper turnings produces nitrogen dioxide in the laboratory.
  
                                                                       4HNO₃ + Cu → Cu(NO₃)₂ + 2NO₂ + 2H₂O
   
• In the laboratory, nitrogen dioxide is made by dehydrating nitric acid to form dinitrogen pentoxide, which is then thermally destroyed to produce nitrogen dioxide.
  
                                                                                            2HNO₃ → N₂O₅ + H₂O
  
                                                                                              2N₂O₅ → 4NO₂ + O₂

Read More: Types of solutions

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Sources of Nitrogen Dioxide

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Nitrogen dioxide is emitted into the atmosphere directly. Nitrogen oxide (NO) and other nitrogen oxides (NO_x) in the air interact with other chemicals to generate nitrogen dioxide.

• The largest source of nitrogen dioxide is the combustion of fossil fuels (coal, gas, and oil), particularly gasoline used in automobiles. 
• It is also formed during the creation of nitric acid, welding and using explosives, refining fuel and metals, commercial manufacturing, and food processing. 
• Natural sources of nitrogen oxides include volcanoes and microbes.
• Buses, cars and trucks are the largest sources of nitrogen dioxide.

Read More: Critical temperature

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Nitrogen Dioxide Uses

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The various uses of Nitrogen Dioxide are as follows:

• Nitrogen dioxide is used as an intermediary in the production of nitric acid.
• It is used to make oxidized cellulose molecules.
• It is used as a catalyst in many reactions.
• The compound is used as an oxidizer for rocket fuels.
• Nitrogen Dioxide is used as a nitrating agent and an oxidizing agent.
• It is used as an intermediate in the production of sulphuric acid.
• The compound is used in the preparation of explosives.
• It is used in the bleach flour.
• Nitrogen Dioxide is used in the manufacturing of cellulose compounds.

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Chemical Properties of Nitrogen Dioxide

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The chemical properties of Nitrogen Dioxide are as follows:

• As an oxidizer: Nitrogen Dioxide is a powerful oxidant because of the weak N–O bond.
• Hydrolysis reaction: Nitrous acid and nitric acid are produced via the hydrolysis reaction.

2NO₂ (N₂O₄) + H₂O → HNO₂ + HNO₃

• Nitrite formation: Alkyl and metal iodides produce similiar nitrites.

2 CH₃I + 2NO₂ → 2CH₃NO₂ + I₂

TiI₄ + 4NO₂ → Ti(NO₂)₄ + 2I₂

Read More: Colloids

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Effect of Nitrogen Dioxide on Health

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Nitrogen dioxide has a number of negative consequences on the body. The following are the effects of Nitrogen Dioxide on Health:

• Nitrogen Dioxide increases airway inflammation
• It will worsen cough and sneeze
• Nitrogen Dioxide will decrease the capacity of the lungs. 
• High inhalation of the compound will cause an allergic response. 
• It will increase the probability of respiratory problems
• It will cause a burning sensation in the eyes and skin.

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Things to Remember 

• Nitrogen Dioxide is a highly reactive gas with molecular formula NO₂ oxides. 
• It is formed by the combination of nitrogen and oxygen. 
• It is an odourless, acidic, and highly corrosive gas and can harm our health and the environment. 
• It is the byproduct of the industrial synthesis of nitric acid.
• Nitrogen dioxide levels in the air have also been associated with an increase in respiratory illness mortality and hospitalizations. 
• It is used as an oxidizing agent and as an intermediate in the manufacture of nitric acid and oxidized cellulose compounds.