The ozone layer is formed in the stratosphere when solar radiation breaks oxygen molecules into oxygen atoms below 240nm wavelengths. The oxygen atoms then combine with oxygen molecules to form ozone molecules in an exothermic reaction where an inert substance absorbs excess energy to prevent ozone decomposition. Ozone is an unstable blue gas that decomposes into oxygen at high temperatures but acts as a powerful oxidizer and reducer in chemical reactions due to its unstable nature.

1. The formation of the ozone layer
The formation of the ozone in the stratosphere region begins with the
photodissociation of oxygen molecules by the solar radiation at
.wavelengths below 240 nm
O2 O + O
The highly reactive O atoms combine with oxygen molecules to form ozone as
follows :
O3 + MO + O2 + M
M : Some inert substance.
The role of M in this exothermic reaction is to absorb some of the excess
energy released and prevent the spontaneous decomposition of the O3
.molecule
O3 O + O2
UV < 240 nm
UV

2. Some physical properties of ozone
Pure ozone is a blue gas with a strong
irritating smell.
It is more soluble than oxygen in water.
It gets liquefied to a deep blue color liquid,
when cooled in liquid air.
It boils at 161 K and solidifies to violet-black
crystals, which melts at 81 K.

3. Some chemical properties of
ozoneDecomposition:
Ozone is unstable compound. Pure ozone decompose instantaneously at 573
K.
2O3 3O2
Oxidizing property :
Ozone acts as a powerful oxidizing agent due to the reaction :
O3 O2 + O
Reducing property :
Ozone reduces peroxides to oxides and in turn gets reduced to oxygen
H2O2 + O3 H2O + 2O2
573 K