Question

What do you mean by ozone hole?

Answer 1

Depletion of ozone layer creates some sort of holes in the blanket of ozone which surround us, this is known as ozone hole.

Answer 2

In Polar regions, stratospheric clouds provide the surface for chlorine nitrate and hypochlorous acid, which react further to give molecular chlorine. Molecular chlorine and HOCl are photolysed to give chlorine-free radicals.

\[\ce{ClONO_{2(g)} + H_2O_{(g)} -> HOCl_{(g)} + HNO_{3(g)}}\]

\[\ce{ClONO_{2(g)} + HCl_{(g)} -> Cl_{2(g)} + HNO_{3(g)}}\]

\[\ce{HOCl_{(g)} ->[hv] \overset\bullet{\text{O}}H_{(g)} + \overset\bullet{\text{C}}l_{(g)}}\]

\[\ce{Cl_{2(g)} ->[hv] \overset\bullet{\text{C}}l_{(g)} + \overset\bullet{\text{C}}l_{(g)}}\]

The chlorine-free radicals lead to the decomposition of ozone as:

\[\ce{\overset\bullet{\text{C}}l_{(g)} + O_{2(g)} -> Cl\overset\bullet{\text{O}}_{(g)} + O_{2(g)}}\]

Hence, a chain reaction is initiated. The chlorine-free radical is continuously regenerated, thereby depleting the ozone layer. This phenomenon is known as the as ‘ozone hole’.