Question

Question 14.7 Write down the reactions involved during the formation of photochemical smog.

Class XI Environmental Chemistry Page 413

Answer 1

smoke and fog is smog

Answer 2

FORMATION OF PHOTOCHEMICAL SMOG :

In the presence of sunlight , NO2 undergoes photolysis to form NO and atomic oxygen. atomic oxygen then combine with the molecular oxygen in the presence of some molecule M ( which acts as a source of transfer of energy ) to form ozone O3. The ozone thus formed reacts with NO to regenerate NO2 and O2 , Thus, NO2 cycle is completed.
the reactions as follows :
NO2 --------> NO + O { in the presence }
O + O2 ------> O3
O3 + NO -----> NO2 + O2

NO2 and O3 are strong oxidizing agents and can react with unburnt hydrocarbons to produce formaldehyde ( HCHO) , acrolein ( CH2=CHCH=O) and peroxyacylnitrates (PAN) , CH3(CO)OONO2

3CH4 +2O3 ----> 3CHCHO ( formaldehyde) + 3H2O