Question

In photochemical reactions smog results in the action of sunlight on saturated hydrocarbon.why? Why not in unsaturated hyrocarbon

Answer 1

They might contain saturated hydrocarbons as well after sufficiently oxidising the unsaturated hydrocarbons, which are primary precursors in them.

once the unsaturated hydrocarbons are oxidised to carbonyl compounds like ketone by free oxygen from ozone, the unsaturation is removed, and hence the formed hydrocarbon is saturated which is the secondary precursor among them.



NO2 and unsaturated hydrocarbons are primary precursors while O3, PAN(saturated hydrocarbon), Formaldehyde, and Acrolein are secondary precursor of photochemical smog.