Site icon O Level Chemistry & IP Chemistry Notes by 10 Year Series Author – Chemistry Specialist

O-Level Chemistry: Nitrogen Dioxide as an Air Pollutant

Being a Chemistry Trainer and also a fellow cyclists (yes guys, i love to cycle), i read this local Straits Times Newspaper article with interest.

Seems like our Nitrogen Dioxide, NO2(g) level within the lower atmosphere level is quite high in Singapore.

NO2(g) is considered a major air pollutant which has the following harmful effects:

1) Eye and lungs irritation and causes breathing difficulties

At high levels, it may even lead to inflammation of the lungs i.e. bronchitis

2) Acid rain consisting of Nitric Acid HNO3 that is highly corrosive

In the presence of oxygen in the air, nitrogen dioxide is converted to nitric acid via the following chemical equation:

4NO2(g) + 2H2O(l) + O2(g)  4HNO3(aq)

Nitric acid corrodes buildings and harms aquatic life and plants.

Do you know that due to acid rain, the Statue of Liberty in the United States of America had been badly corroded. In the year of 1983, the US Government launched a campaign to restore this historical figure of US Chemistry in action indeed!

NO2(g) is formed due to 2 main sources:

1) Lightning activities (which we have no control over since it is a natural source and it is NOT a daily source)

2) Vehicle exhaust fumes where high temperature around vehicles engine (which is a man-made source) causes 21% O2(g) and 78% N2(g) in the air to react to form oxides of nitrogen, NOx(g) which is mainly nitrogen monoxide, NO(g) and nitrogen dioxide, NO2(g).

Nitrogen reacts with oxygen at high temperature to form nitrogen monoxide or nitric oxide, NO(g).

N2(g) + O2(g)  2NO(g)

Nitrogen monoxide reacts with oxygen to form a brown colour gas called nitrogen dioxide, NO2(g).

2NO(g) + O2(g)  2NO2(g)

From the article, it shows that as concentration of air particulates (unburnt hydrocarbons) increases due to incomplete combustion of fossil fuels in vehicle exhaust fumes, there is also an increase in the concentration of nitrogen dioxide, NO2(g).

Since the satellites images have shown that the recent haze in Singapore is not from Indonesian fires (slash and burn method), it should be from the amounts of vehicle exhaust fumes produced locally on a daily basis.

Time to ponder about if Singapore should encourage less driving….for our health and environment.

This is a good case study for GCE O-Level Pure Chemistry and Combine Science Chemistry students in Singapore to put their concepts learned in school into actual practice and application.

Same applies to Chemistry students worldwide doing other syllabus. This can be particularly severe in large cities, where traffic is heavy.

I hope you find the content easy for your understanding and if you have any questions, leave me a comment below. Feel free to share this blog post with your friends.

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PS: Under related articles below, there are several blog post discussions and questions related to Air & Atmosphere. You can also do a keyword search using the search box at the top right hand corner.

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