• # question_answer 49)   Oxidation of sulphur dioxide into sulphur trioxide in the absence of a catalyst is a slow process but this oxidation occurs easily in atmosphere. Explain how does this happen? Give chemical reactions for the conversion of $S{{O}_{2}}$into$S{{O}_{3}}$.

The oxidation of sulphur dioxide into sulphur trioxide can occur both photo chemically or non-photo chemically. In the near ultraviolet region, the $S{{O}_{2}}$ molecules react with ozone photo chemically.                                 $S{{O}_{2}}+{{O}_{3}}\xrightarrow{hv}S{{O}_{3}}+{{O}_{2}}$                                 $2S{{O}_{2}}+{{O}_{2}}\xrightarrow{hv}2S{{O}_{3}}$ Non-photo chemically,$S{{O}_{2}}$ may be oxidised by molecular oxygen in presence of dust and soot particles. $2S{{O}_{2}}+{{O}_{2}}\xrightarrow{Particles}2S{{O}_{3}}$