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spraying the hot gases with a suspension of quicklime. This process, called "scrubbing," creates huge amounts
of calcium sulfite to dispose of. Retrofitting of scrubbers onto established power plants is very expensive and
significantly raises the cost of electricity . Back Forward Main Menu TOC Study Guide TOC Textbook Website MHHE Website 3 62 / Chemistry in the Atmosphere
14. Give three sources of CO2 in the atmosphere.
Name three "greenhouse" gases besides carbon dioxide and water.
Below what pH is rain considered to be "acid rain?"
SO2 and SO3 are acid anhydrides. Write reactions to show their conversion into acids. PHOTOCHEMICAL SMOG
2. Distinguish between primary and secondary pollutants.
Describe how ozone is formed in polluted air. Photochemical smog is formed by the reactions of automobile exhaust in the presence of sunlight.
Reactions initiated by photons are called photochemical reactions. The text points out that smog begins with
certain primary pollutants. These substances may or may not be objectionable by themselves. These are
transformed by sunlight or by ordinary chemical reactions into secondary pollutants. Secondary pollutants are
involved directly in the buildup of smog. Nitric oxide is a good example of a primary pollutant. It is formed at
the high temperatures inside an internal combustion engine when nitrogen and oxygen from air react. Nitric
oxide does not build up in the air because it is rapidly converted to nitrogen dioxide.
N2 (g) + O 2 (g) → 2NO(g)
2NO(g) + O2 (g) → 2NO 2 (g)
Nitrogen dioxide is involved in a chain of reactions that produce ozone. First NO2 is photochemically
decomposed by sunlight.
NO2 (g) + hν → NO(g) + O(g)
Oxygen atoms initiate a number of reactions in polluted air. An important one is the formation of ozone.
O(g) + O2 (g) → O 3 (g)
Exposure to 0.1 to 1.0 ppm of ozone produces headaches, burning eyes, and irritation to the respiratory
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This note was uploaded on 09/15/2009 for the course CHEM 102 taught by Professor Bastos during the Spring '08 term at Adelphi.
- Spring '08