Chemical And Photo Chemical Reactions In the Atmosphere

Formation of Smog :

Smog is a mixture of smoke and fog in suspended droplet form. The brownish smog like appearance that frequently forms on clear, sunny days over large cities with significant amounts of automobile traffic.

Types Of Smog :

There are two types of smog.

1. London Smog

2. Los Angles Smog (or) Photochemical Smog

LONDON SMOG :

It is a coal smoke plus fog. Fog mainly consists of mixture of SO2 + SO3 + humidity. It is bad in morning hours and becomes worse after sunrise. This is due to sunlight induced oxidation SO2 + SO3, Followed by reaction with humidity giving sulphuric acid and aerosd.

So2 + (O) -----------> SO3

SO3 + H2O -----------> H2SO4

LOSANGELS SMOG Or Photochemical SMOG :

It is not related to smoke (or) fog. It is formed by the combination of NO, NO2, CO2, H2O, CO , SO2 and unburnt hydrocarbon particles. The important reaction is dissociation of NO2 In sunlight.

N2 + O2 --------> 2NO

2NO + O2 ----------> 2NO2

No2 ---------> NO + O

O2 + O ----------> O3

hydrocarbon + O2, O, O3, NO2 , NO ---------> Oxidized Hydrocarbons.

These Oxidized hydrocarbons with ozone in the presence of humidity causes photochemical smog.

Health effects of Smog.

1. It causes irritation to eyes and lungs.

2. It damages plants.

3. It irritates nose, throat, etc.,

4. It also causes bronchial irritation.

Environmental effects of Smog.

1. It produces acid rain.

2. It damages plants and trees.

3. Smog can reduce visibility.

Remedial measures of Smog.

1. By decreasing nitrogen oxides and hydrocarbon levels in the air.

2. By using unleaded petrol in automobiles.

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