Stratospheric ozone is in dynamic equilibrium with oxygen. Give the equations that describe the formation of ozone from oxygen and its depletion in the stratosphere in the presence of ultraviolet light.

Formation:

Depletion:

Formation

\({{\text{O}}_{\text{2}}} \to {\text{2O}} \bullet \) and \({{\text{O}}_2} + {\text{O}} \bullet  \to {{\text{O}}_3}\);

Depletion

\({{\text{O}}_3} \to {{\text{O}}_2} + {\text{O}} \bullet \) and \({{\text{O}}_3} + {\text{O}} \bullet  \to {\text{2}}{{\text{O}}_2}\);

Part (a) produced mixed responses with some candidates writing appropriate equations, and some writing only one equation for the formation and depletion of ozone when two equations were needed for each process. A few candidates seemed to have no idea of the formula of ozone.