Oxides of Nitrogen

Imagine walking through the city center when it is peak traffic time; this would basically imply walking through volumes of smells from all the vehicle fumes. It's also an allusion to one of the major environmental issues related to oxides of nitrogen, popularly known as NOx. These are by-products of Combustion processes in vehicles, power plants, and industrial facilities. The ones including nitric oxide (NO) and nitrogen dioxide (NO₂) have huge implications for air pollution, smog, acid rains, etc., and serious negative impacts on the health of people, particularly in the form of respiratory problems.

This Story also Contains

1. Nitrogen Oxides
2. Types and Aspects of Nitrogen Oxides
3. Relevance and Applications in Real Life and Academics
4. Some Solved Examples
5. Summary

Nitrogen Oxides

Oxides of nitrogen are a collection of nitrogen-Oxygen compounds that have different oxidation states of nitrogen. The deeper members include nitric oxide, NO, nitrogen dioxide, NO₂, nitrous oxide, N2O, and nitrogen trioxide, N₂O₃. Nitric oxide is a colorless gas that oxidizes in air to yield the reddish-brown toxic gas, nitrogen dioxide. Nitrous oxide is popularly referred to as laughing gas; it represents a greenhouse gas and an anesthetic. Nitrogen trioxide is, however, rather an unstable compound and thus only exists in small quantities. These oxides participate in many different atmospheric chemistry roles, both in natural processes and as anthropogenic pollution.

Types and Aspects of Nitrogen Oxides

Of the nitrogen oxides, there exist a few with different traits and effects. The vast majority of NO is created by high-temperature combustion processes. It is easily oxidized to NO₂. Most of the urban smog comes from NO₂; more serious health effects can range from simple respiratory problems to asthma. N₂O is not quite so reactive but plays a central role in global warming and the destruction of the ozone layer. Another important issue is the formation of nitric acid, HNO3, by NOx reacting with water vapor to form nitric acid resulting in acid rain. Therefore, each of these oxides of nitrogen poses a special problem and needs well-directed programs for control.

oxides are given in Table given below.

Relevance and Applications in Real Life and Academics

The effects of nitrogen oxides are not limited to environmental degradation; they have broad implications for public health and policy decisions in terms of enforcement of strict emission standards for automobiles and industries in urban centers with high NOx levels and heightened incidents of respiratory diseases. It is also duly important academically, considering how important understanding the study of NOx is for scholars in elucidating the atmospheric chemistry underlying environmental science and engineering solutions to pollution. Such novel technologies have been invented to trim the NOx emissions at their sources, like catalytic converters in cars and SCR systems in industrial plants. In addition, stringent research works have been underway in renewable energies and alternative fuels that would reduce the dependence on fossil fuel and, thereby, NOx generation. These measures entail an interrelation between scientific research and an update in technology with policy initiatives to address challenges in nitrogen oxide.

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Some Solved Examples

Example 1

Question: The set that represents the pair of neutral oxides of nitrogen is:
1.$\mathrm{N}_2 \mathrm{O}$ and $\mathrm{NO}_2$
2. $\mathrm{N}_2 \mathrm{O}$ and $\mathrm{N}_2 \mathrm{O}_3$
3.NO and $\mathrm{N}_2 \mathrm{O}$ Correct
4. (NO and $\mathrm{NO}_2$)

Solution:
NO, and $\mathrm{N}_2 \mathrm{O}$ are neutral oxides, whereas $\mathrm{N}_2 \mathrm{O}_3, \mathrm{NO}_2$ and $\mathrm{N}_2 \mathrm{O}_5$ are acidic oxides. Therefore, the correct answer is option (3): .

Example 2
Question:

The oxidation states of nitrogen in (mathrm{NO}), (mathrm{NO_2}), (mathrm{N_2O}), and (mathrm{NO_3^-}) are in order of:
1.$\mathrm{NO}>\mathrm{NO}_2>\mathrm{N}_2 \mathrm{O}>\mathrm{NO}_3^{-}$
2. $\mathrm{NO_2} > \mathrm{NO_3^-} > \mathrm{NO} > \mathrm{N_2O}$
3. $\mathrm{N_2O} > \mathrm{NO_2} > \mathrm{NO} > \mathrm{NO_3^-}$
4. $\mathrm{NO_3^-} > \mathrm{NO_2} > \mathrm{NO} > \mathrm{N_2O}$

Solution:
The oxidation states of nitrogen in these compounds are:
$\mathrm{NO}$ : +2
$\mathrm{NO_2}$ : +4
$\mathrm{N_2O}$ : +1
$\mathrm{NO_3^-}$ : +5

The decreasing order of the oxidation state of nitrogen is: $\mathrm{NO_3^-} > \mathrm{NO_2} > \mathrm{NO} > \mathrm{N_2O}$. Therefore, the correct answer is option (4).

Example 3
Question: On heating, lead (II) nitrate gives a brown gas (A). The gas (A) on cooling changes to a colorless solid/liquid (B). (B) on heating with NO changes to a blue solid (C). The oxidation number of nitrogen in solid (C) is:
1. +5
2. +2
3. +3
4. +4

Solution:
The reactions involved are:

$
\mathrm{Pb}\left(\mathrm{NO}_3\right)_2 \xrightarrow{\Delta} \mathrm{PbO}+\underset{\text { Brown gas }}{2 \mathrm{NO}_2}+\frac{1}{2} \mathrm{O}_2(\mathrm{~g})
$

$
\mathrm{NO}_2 \xrightarrow{\text { Cooling }} \mathrm{N}_2 \mathrm{O}_4
$

(B)

$
\mathrm{N}_2 \mathrm{O}_4+\mathrm{NO} \xrightarrow{\Delta} \mathrm{N}_2 \mathrm{O}_3
$ Blue Solid
(C)

The oxidation number of nitrogen in N₂O₃ is +3. Therefore, the correct answer is option (3).

Summary

Oxides of nitrogen span into a pivot in the knowledge and struggle against air pollution and climate change. The forms range from nitric oxide to nitrous oxide through the different paths on health and environmental effects. NOx mitigation is necessary through research into technological and policy paths; their chemistry holds an insight into how they react to the environment and how these sour effects can be controlled. Measures for minimizing nitrogen oxide should change as much as society itself does.