Question

Which aerosols deplete ozone?

Answer 1

Hint: Aerosols are liquids or solid particles in air. Some aerosols released from refrigerants have a hazardous effect on the earth’s atmosphere.

Complete step by step solution:
-Aerosols is an abbreviation for aero-solution. It is a suspension of fine solid particles or even liquid droplets in air or any other gas. These can be natural or anthropogenic (particles released due to human activities). Natural ones are dust, fog, mist, pollen etc. Anthropogenic aerosols are mainly air pollutants and smoke released from industries or from exhaust or usual human activities.
-Freon is aerosol which is produced from refrigerants and aerosol propellants. These are mainly halocarbon products. Examples of Freon are chlorofluorocarbon or CFC and chlorodifluoromethane. These aerosols can cause ozone depletion. Freons such as CFC consist of chlorine. These react with ultraviolet rays and produce chlorine atoms. These chlorine atoms act as a catalyst to break down thousands of ozone molecules.

$CFC{{l}_{3}}+\text{electromagnetic radiation}\to C{{l}^{\bullet }}+{}^{\bullet }CFC{{l}_{2}}$
Ozone is a highly reactive molecule which is easily reduced to a stable oxygen molecule.

$O+{{O}_{3}}\to 2{{O}_{2}}$

The chlorine atom reacts with ozone and takes up one oxygen atom and forms chlorine monoxide and oxygen. This chlorine monoxide can react with another ozone molecule, releasing chlorine as an atom and two oxygen molecules. This occurs more rapidly than the formation of ozone in the ozone layer.

$C{{l}^{\bullet }}+{{O}_{3}}\to ClO+{{O}_{2}}$
$ClO+{{O}_{3}}\to C{{l}^{\bullet }}+2{{O}_{2}}$

A single chlorine atom goes on destroying many ozone molecules for upto two years if it is not removed from the stratosphere. Hence, Freons are the aerosols which cause ozone depletion.

Note: Ozone is not a very stable molecule. It can be destroyed by other species such as hydroxides, bromides etc. These are present in the atmosphere. But as an aerosol Freons can destroy ozone.