Chlorofluorocarbons (CFCs) and Ozone Depletion
Chlorofluorocarbons that are notorious for ozone depletion, is a group of chemicals being used in refrigerators and other cooling devices, and in the aerosols sprays and insulating foam production. In simple words we can say that CFCs are chemicals containing atoms of chlorine, carbon and fluorine. CFC when released are not chemically reactive in the lower level (Troposphere) of the atmosphere. But when they reach upper part of the atmosphere (Stratosphere) – where the ozone layer is present – these react with harmful ultraviolet radiations coming from the sun.
In the reaction CFCs are broken down to release chlorine which then reacts with reacts with triatomic ozone -producing chlorine monoxide and diatomic oxygen and thus depleting the ozone layer. These reactions can be expressed as below respectively;
\[ CFC’s+Ultraviolet Radiations —–>Chlorine \]
\[ Chlorine+O_3 (ozone)—->ClO (Chlorine monoxide)+O_2(Oxygen) \]
Ultraviolet radiations coming from sun then reacts again with this produced diatomic oxygen to divide it into two anatomic oxygen atoms which individually react with other diatomic oxygen atoms to form ozone again.
We can understand it as below;
\[ O_2 (produced in above reaction of CFCs) + Ultraviolet Radiation from sun——> O+O \]
Then each of these to mono atomic oxygen atoms undergoes the following reaction individually to form ozone again i-e
\[ O+O_2——>O_3 \]
Natural formation and deformation of ozone
Diatomic oxygen’s ambient natural presence also follow above pattern to form ozone naturally. It means that ultraviolet radiations react with readily present diatomic oxygen in the stratosphere to form two mono atomic oxygen atoms. Which further react with other diatomic oxygen atoms to form ozone naturally.
\[ O_2 (present naturally in stratosphere) + Ultraviolet Radiation from sun——> O+O \]
\[ O(produced in above natural reaction+O_2 (present naturally) ——>O_3 (ozone)\]
Ozone produced above then naturally reacts with ultraviolet radiations again to from one diatomic oxygen molecule and one atom of oxygen.
\[ O_3+Ultraviolet Radiation—-O_2+O \]
This diatomic oxygen further reacts with mono atomic oxygen to form ozone. While the single atom of oxygen reacts with other ozone molecule to to form diatomic oxygen molecules and so on .
So, it clear that ozone is forming deforming naturally. But there is a balance in between this formation and deformation. In other words ozone is fighting with ultraviolet radiations. It fights to consume them in the upper levels of the atmosphere before they could reach the earth surface in this way!
On the other hand deformation by the CFC’s is to disturb this balance by extra and quick ozone depletion layer. That is why Chlorofluorocarbons dangerous for us because these deplete ozone layer protecting us from ultraviolet radiations coming from the sun.