Environmental Chemistry & Fractional Distillation of Crude Oil

SO2	Produced when sulfur containing fossil fuel is burned Effects – Irritation in eyes, Stiffening of flower beds which eventually fall from plants, Asthama, Bronchitis in human beings
NOx	NO3- [arr] Acts as a fertilizer to the soil Automobile exhaust produces NO2 which damages plant leaves & retard rate of photosynthesis Automobile exhaust also causes red haze & lung irritation
HCs	Formed by incomplete combustion of fuels esp. automobile Carcinogenic – Causes cancer, Causes early aging, Plants leaves shredding
CO2	Formed by respiration, burning of fuels, decomposition of lime, volcanic eruption A major greenhouse gas
CO	Formed by incomplete combustion of C, Automobile exhaust, Cigarette smoke Blocks delivery of oxygen to tissues (Combines with hemoglobin to form carboxy-hemoglobin, which is highly stable & reduces oxygen carrying capacity of blood) Helps in production of steel & in extraction of Fe from Fe ore
Classical Smog	Occurs in cool humid climate Chemically reducing hence called reducing smog Smoke + fog + SO2
Green House Gases	CO₂, CH4, CFC, N₂O, SF_6, HFCs, PFCs, CCl_4,CH₃CCl₃
CH4	It is mainly CH4 which burns in fossil fuels, produced by burning of vegetation or rotting

Occurs in warm, dry & sunny climate
Results from the action of sunlight on unsaturated HC & oxides of Nitrogen produced by factories & automobile
Chemically oxidizing hence called oxidizing smog
Ozone + Acrolein + Formaldehyde + Peroxyacetyl Nitrate (PAN) are produced which cause serious health problems, severe plant damage, cracking of rubber & corrosion
Catalytic Converter – Prevent release of NO & HC to environment

Ozone protects us from UV rays which causes skin cancer (Melanoma)
Depletion of ozone layer – By Ozone depleting substances (ODS) which are non-toxic, non-reactive & nonflammable
Main ODS– CFCs, HCFCs, Halons, CCl4, NOx, CH3CCl3 (Methyl chloroform)
Major Sources – Solvent Cleansing products >Refrigeration & Air conditioners > Foam Products
CFCs are the most widely used ODS, accounting for over 80% of total stratospheric ozone depletion
ODS + UV [arr] Cl (Chlorine radicals which causes breakdown of Ozone)

Acid rain (Ph < 5.6) is caused by emissions of sulfur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids (H₂SO₄& HNO₃)

Rain with Ph < 5.6

Rain with oxides of sulfur & nitrogen (SO2 & NO2)

Crude oil is heated until it boils and then the hydrocarbon gases are entered into the bottom of the fractionating column.
As the gases go up the column the temperature decreases.

The hydrocarbon gases condense back into liquids and the fractions are removed from the sides of the column.
Higher HC degrade into lower HC by high heating (cracking) in following order –

Gaseous HCs

Petroleum Ether

Gasoline

Kerosene

Diesel / Gas Oil

Lubricating oil / Greases

Paraffin Wax

Asphalt & Coke

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