Question

What do you understand by ozone layer depletion? Mention its cause and write chemical reactions responsible for ozone layer depletion

Answer 1

Ozone layer depletion is one of the most serious problems faced by our planet earth. It is also one of the prime reasons which are leading to global warming. Ozone is a colourless gas which is found in the stratosphere of our upper atmosphere. The layer of ozone gas is what which protects us from the harmful ultraviolet radiations of the sun. The ozone layer absorbs these harmful radiations and thus prevents these rays from entering the earth’s atmosphere. Ultraviolet radiations are high energy electromagnetic waves emitted by the sun which if enters the earth’s atmosphere can lead to various environmental issues including global warming, and also a number of health related issues for all living organisms. 
The main things that lead to destruction of the ozone gas in the ozone layer. Low temperatures, increase in the level of chlorine and bromine gases in the upper stratosphere are some of the reasons that leads to ozone layer depletion. But the one and the most important reason for ozone layer depletion is the production and emission of chlorofluorocarbons (CFCs).
Step 1. "Photolysis" (splitting by sunlight) of CFC's in the stratosphere 

Cl2CF2 + UV light --> ClCF2 + Cl 

Step 2. Catalytic destruction of ozone 

Cl + O3 --> ClO + O2 

ClO + O3 --> Cl + 2O2