Worksheet Ch.16
–
ORGANIC AIR POLLUTANTS AND
PHOTOCHEMICAL SMOG
PART A – CLOZE EXERCISE
1. The effects of organic pollutants in the atmosphere can be broadly divided between …………………
…………………………….. and ………………………………………………………………………
Global distillation and fractionation of persistent organic pollutants has the effect of …………………
…………………………………………………………………………………………………………..
2. In considering reactions and fates of organic pollutants, the symbols hrepresents …………………..
………………………………………………………………. , which can be absorbed by a molecule,
and the most important reactive intermediate species is ………………………………………………..
3. Of total hydrocarbons in the atmosphere only about __________ come from human activities, largely
because of the huge amounts of _______________________ generated from natural sources. Most of
the hydrocarbons emitted by plants are _________________________ , which come from plants such
as …………………………………………………………………………………………………...
4. The three major classes of pollutant hydrocarbons are …………………………………………………
………………………………………………….. of which _________________________ are the most
reactive because of their __________________ bonds.
5. Frequently the first species formed, other than unstable reaction intermediates, in the photochemical
oxidation of atmospheric hydrocarbons are ……………………………………………….. , which may
be either ………………………………………………………………………………… The simplest
and most widely produced of the carbonyl compounds and the one most commonly encountered in the
atmosphere is _________________________________.
6. The lighter alcohols are readily removed from the atmosphere because of …………………………….
…………………………………………………….
7. An ether used as a gasoline additive is ………………………………………………………………...
8. Compounds containing the COOH group are referred to as …………………………………………….
9. An organohalide that is a known human carcinogen is …………………………………………………
The class of organohalides shown to be damaging to the stratospheric ozone layer consists of the ……
………………………….... , and extremely stable organohalides containing two aromatic rings, now
banned because of their environmental persistence, are the …………………………………………….
The compounds developed to substitute for the ozone depleting organohalides mentioned above all
contain …………………………………………………………………………….
10. The alkyl thiols belong to the general class of ……………………………………………………….…..
compounds and are noted for their ………………………………………………………………...
11. Compounds noted for their rotten fish odours are the ………………………………………………. ..
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Fundamentals of Environmental Chemistry.
Stanley. E. Manahan
© 2001 CRC Press LLC
12. The three ingredients required to generate photochemical smog are ……………………………………
………………………………………………………... In addition to hydrocarbons, a compound
involved in photochemical smog formation that is emitted by internal combustion (automobile) engines
is _____________ . The device now used to destroy smog-forming pollutants from automobile engines
once they have been generated by the engine is the ………………………………………………….. .
A driving force behind photochemical smog formation is that hydrocarbons and most other organic
compounds in the atmosphere are ………………………………………………………………………..
………………………………………. and tend to be _____________________ through a series of
steps. A simple inorganic oxidant characteristic of the presence of photochemical smog is __________
13. Two kinds of behaviour that puzzled early investigators of the smog-forming process are …………
……………………………………………………………………………………………………………
……………………………………………………………………………………………………………
The initial photochemical reaction that initiates smog formation is:
……………………………………………………………………………………………..
14. A reaction between a hydrocarbon, RH, and an oxygen atom that produces two free radicals, one of
which is the most significant reactive intermediate species in the smog-forming process is:
…………………………………………………………………………………………
15. A common reaction of HO• that removes this radical from the atmosphere and produces an inorganic
acid is …………………………………………………………………………………………………
16. The main reaction that alkanes can undergo with O atoms or HO• radical is the __________________
reaction, whereas alkenes can also undergo _____________________ reactions. Alkenes can react
with _________________________ to produce a species in which 3 oxygen atoms are bridged
between 2 carbon atoms. The first class of stable, though reactive, species formed during the oxidation
of hydrocarbons during smog formation consists of ___________________________ which, unlike
most common organic compounds in the atmosphere can undergo direct ………………………………
……………………………………… The fact that hydroxyl radical reacts with some hydrocarbons at
rates that are almost diffusion-controlled means that ……………………………………………………
……………………………………………………………………….
17. A reactive species in the atmosphere that is especially important at night is the ……………………….
……………………………………………..
18. Hydrocarbon reactivity is commonly based upon the interaction of hydrocarbons with ……………….
…………………………………………... The least reactive common hydrocarbon is _____________ .
A hydrocarbon from conifer trees that is 9000 times as reactive is __________________________ .
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Fundamentals of Environmental Chemistry.
Stanley. E. Manahan
© 2001 CRC Press LLC
19. Two major classes of inorganic products from smog are ………………………………………………. ,
which have the effects of ………………………………………………………………………………..
…………………………………………………………………..
20. The harmful effects of smog occur mainly in the four areas of ………………………………………….
……………………………………………………………………………………………………………
Ozone adversely affects rubber by ……………………………………………………………………….
21. The three major oxidants that adversely affect plants are ………………………………………………
…………………………………………………………………………………………………………..
See p586 From the late 1980s until about 2000, the number of days that Los Angeles air has exceeded
the 120 ppbv ozone standard has dropped from ______________ to around _________________ .
PART B – SHORT ANSWER
22. Why is a modern automotive catalytic converter called a “three-way conversion catalyst?”
23. What is the purpose of alumina in an automotive exhaust catalyst? What kind of material actually catalyzes the
destruction of pollutants in the catalyst?
24. What is the main species responsible for the oxidation of NO to NO2 in a smoggy atmosphere?
25. What pollution problem does a lean mixture aggravate when employed to control hydrocarbon emissions from
an internal combustion engine? See figure 16.10
26. Identify 3 sources of methane gas released into the atmosphere.
3|Page
Fundamentals of Environmental Chemistry.
Stanley. E. Manahan
© 2001 CRC Press LLC