Photochemical formation of smog

PHOTOCHEMICAL FORMATION OF SMOG
Photochemical Reactions in Atmosphere
What is Smog ?
Formation of Photochemical smog
Probable Mechanism for Smog formation

1. PHOTOCHEMICAL FORMATION OF SMOG SUBMITTED BY: Keshav Kumar Singh Y19266023 Department of Chemistry Dr . Harisingh Gaur Vishwavidyalaya (A Central University) Sagar, M.P.  

2. Natural photochemical phenomena have contributed to the evolution of life and have allowed its continued existence on the Earth. let us discuss atmospheric structure because photochemical reactions depend on atmospheric structure. Region Altitude range (Km) Temperature Range (° C) Important Chemical Species 1) Troposphere 0-11 15 to -56 N 2 , O 2 , CO 2 , H 2 O 2) Stratosphere 11-50 -56 to -2 O 3 3) Mesosphere 50-85 -2 to -92 O 2 + , NO + 4) Thermosphere 85-500 -92 to 1200 O 2 + , NO + , O + Photochemical Reactions in Atmosphere

3. What is Smog ? Hydrocarbons and other organic compounds in the atmosphere are susceptible to oxidation through a series of steps of chemical and photochemical reactions. As a result many noxious secondary pollutant products and intermediates are produced, which belong to the category of photochemical smog. Smog is often seen as brown haze above large cities. Frequency and severity depends on local topography, climate, population density, fossil fuel use. Deforestation and burning may also contribute to smog formation. Toxic gases leads to breathing difficulties and health problems.

4. Two types of pollutants which produce photochemical smog are primary pollutants and secondary pollutants. Primary Pollutant : Harmful substances put directly into air by human activities. These include oxides of nitrogen, volatile organic compounds and carbon monoxide . Secondary Pollutant : These include ozone, Nitrogen Dioxide, hydrogen peroxide, peroxyacetyl nitrate(PAN)

5. Formation of Photochemical smog

6. Hydrocarbons do not react readily with sunlight, but they are reactive towards other substances produced photochemically. An important characteristic of atmosphere which are loaded with large quantities of automobile exhausts, trapped by an inversion layer and at the same time exposed to intense sunlight, is the formation of photochemical oxidant in the atmosphere. This gives rise to the phenomenon of Photochemical smog. Photochemical smog is an oxidizing smog having high concentration of oxidant (i.e., O 3 and NO 2 )

7. Probable Mechanism for Smog formation

8. REACTIONS INVOLVED

9. REFERENCES: Photochemistry and pericyclic reactions by Jagdamba Singh and Jaya Singh. https://www.google.com/search?q=health+effects+due+to+photochemical+smog&rlz=1C1RXQR_enIN928IN928&sxsrf=ALeKk017ePkVhLaQC3A0ns_hHTbHW8mxAA:1621597588089&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjviNPh2drwAhWIxzgGHYV7CDYQ_AUoAXoECAEQAw&biw=1536&bih=666#imgrc=VhzeDj37C1W_vM https://www.epa.sa.gov.au/files/8238_info_photosmog.pdf https://chem.libretexts.org/Ancillary_Materials/Exemplars_and_Case_Studies/Exemplars/Environmental_and_Green_chemistry/Photochemical_Smog https://www.sciencedirect.com/science/article/pii/S0166111608717928 https://www.sciencedirect.com/science/article/abs/pii/S1389556703000066

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