Question

What do CFCs stand for? Name some devices where CFCs are used. Why are CFCs considered pollutants?

Answer 1

Hint: CFCs stand for chlorofluorocarbons. These are nonflammable chemicals which are used as refrigerants, in manufacturing of aerosols, etc. These are considered pollutants as they destroy the protective ozone layer and are responsible for increasing temperature conditions leading to global warming.

Complete Step By Step Solution
Chlorofluorocarbons are made up of chlorine, fluorine and carbon atoms as their name suggests. These are highly used in refrigerators and air conditioning systems because they are chemically inert and volatile in nature. These are known as Freon and were first developed by the team of Thomas Midgely. The chlorofluorocarbons release chlorine atoms when they break down in the presence of UV radiations and thus deplete the ozone layer. The chlorine released reacts with ozone molecules and forms oxygen which reduces the ozone quantity causing its depletion. This is the reason why CFCs are considered as pollutants. These also contribute towards increasing atmospheric energy leading to warming effects.
CFCs are inert in Troposphere but they are broken in the presence of UV radiations in Stratosphere; the release of chlorine atoms and their reaction with ozone sets up a chain reaction which leads to the destruction of thousands of ozone molecules thus depleting our protective ozone layer.
CFCs are used as refrigerants in refrigerators and air conditioning systems, ex- R11, R12.

Note
Due to the large ozone destruction nature of CFCs, they are nowadays being replaced by hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) which cause ozone destruction to a much lesser extent than CFCs. They are also replacing CFCs as refrigerants. CFCs are outlawed by 197 countries.