Advertisements
Advertisements
Question
State the chemicals responsible for ozone layer destruction.
Advertisements
Solution
Chemicals responsible for the destruction of the ozone layer:
(1) Excessive use of CFCs:
CFCs enter the atmosphere because of their excessive use in solvents, aerosol sprays, propellants, refrigerants and blowing agents for plastic foams.
CFCs are decomposed by UV rays to highly reactive chlorine which is produced in the atomic form.
CF2Cl2(g) → CF2Cl(g) + Cl(g)
This free radical [Cl] reacts with ozone, and chlorine monoxide is formed.
Cl(g) + O3(g) → ClO(g) + O2(g)
This causes depletion of ozone, and chlorine monoxide further reacts with atomic oxygen to produce more free radicals of chlorine.
ClO(g) + O(g) → Cl(g) + O2(g)
Again this free radical [Cl] destroys ozone, and the process continues giving rise to large-scale ozone depletion.
(2) The fuel of planes:
When the fuel of planes burns, a large quantity of nitric oxide and other gases is emitted in the atmosphere. Nitric oxide reacts with ozone to form nitrogen dioxide and nitrogen trioxide.
NO(g) + O3(g) → NO2(g) + O2(g)
NO2(g) + O3(g) → NO3(g) + O2(g)
This also causes depletion of ozone.
RELATED QUESTIONS
What is the function of ozone in the upper atmosphere?
Which radiations are absorbed by ozone layer?
How Ozone is Formed?
O2 is converted into O3 by the action of :
(a) infrared radiations
(b) ultraviolet radiations
(c) gamma radiations
(d) cosmic radiations
Match the items in column I with the closely related ones in column II.
| Column I | Column II | ||
| (i) | Chlorofluorocarbons (CFCs) | (a) | Global warming |
| (ii) | Fly ash | (b) | Biodegradable |
| (iii) | Cow dung | (c) | Nuclear radiation pollutant |
| (iv) | CO2 and methane | (d) | Acid rain |
| (v) | Sulphur dioxide | (e) | Industrial waste |
| (vi) | Iodine-131 | (f) | Ozone depletion |
How is ozone formed in the upper atmosphere? State its importance. What is responsible for its depletion? Write one harmful effect of ozone depletion.
Number of Oxygen atom in Ozone.
Give balanced equations for formation of ozone molecules from oxygen molecules. What type of reaction takes place, during the formation.
Name or state the following:
An atmospheric pollutant responsible for both global warming and ozone depletion.
Depletion of ozone is mainly due to
