Answer:
Two types of
the compounds have been found responsible for destruction of ozone.
(i) Nitric oxide: Though, nitrous oxide is quite
inert in the stratosphere, it is photo chemically decomposed into more reactive
nitric oxide.
\[N{{O}_{2}}+hv\to
NO+N\]
Nitric oxide, so formed, undergoes the following chain reactions:
\[\underset{Net\,reaction}{\overset{{}}{\mathop{{}}}}\,\frac{\begin{align}
& NO+{{O}_{3}}\to N{{O}_{2}}+{{O}_{2}} \\
& {{O}_{3}}+hv\to {{O}_{2}}+O \\
& N{{O}_{2}}+O\to NO+{{O}_{2}} \\
\end{align}}{2{{O}_{3}}\to 3{{O}_{2}}}\]
Thus, in presence of oxides of nitrogen, the rate of decomposition
of \[{{O}_{3}}\] increases.
(ii) Chlorofluorocarbons: Chlorofluorocarbons absorb produce chlorine atoms by breaking carbon-chlorine
bonds.
\[C{{F}_{2}}C{{l}_{2}}+hv\to C{{F}_{2}}Cl+Cl\]
\[CFC{{l}_{3}}+hv\to CFC{{l}_{2}}+Cl\]
Chlorine atoms undergo the following reactions:
\[\underset{Net\,reaction}{\overset{{}}{\mathop{{}}}}\,\frac{\begin{align}
& Cl+{{O}_{3}}\to ClO+{{O}_{2}} \\
& ClO+O\to Cl+{{O}_{2}} \\
\end{align}}{{{O}_{3}}+O\xrightarrow{Cl}2{{O}_{2}}}\]
Chlorine atoms catalyse the decomposition of\[{{O}_{3}}\].
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