Geology Reference
In-Depth Information
(iv) Explain the following statement: ''Ozone can be photolysed
both in the troposphere and stratosphere leading to quite
different chemistry''.
(v) Why is the stratosphere separate from the troposphere?
(vi) Discuss the chemistry of ozone in the stratosphere in terms of
the relationships between catalytic species and the different
types of reservoir chemistry.
(vii) Explain the main chemical and physical features of the so-called
ozone ''hole''.
(viii) The hydroxyl radical (OH) has different role in the stratosphere
and troposphere. Give an example of the reactions of OH in
troposphere and stratosphere and describe their significance.
(ix) What role does the boundary layer play in the mixing of gases?
(x) What are the main reactions that contribute to the formation of
the so-called photochemical smog?
(xi) What physical, chemical and social effects can aggravate the
formation of photochemical smog?
(xii) Peroxyacetylnitrate (PAN) is of interest as a characteristic
product of tropospheric photochemistry.
(i) How is PAN formed in the atmosphere?
(ii) The unimolecular decomposition of PAN to peroxy acetyl
radicals and NO 2 is strongly temperature dependent. The
following expression gives the temperature dependence of
the unimolecular rate constant:
:
k ¼ 1 : 0 10 17 exp 14 ; 000
T
If the lifetime is given by 1/k, calculate the atmospheric
lifetime of PAN at T ¼ 310, 298, 290 and 280K.
(iii) In the light of your answer to part (b), comment on the
potential of PAN as a reservoir for reactive nitrogen in
remote regions.
(xiii) Explain the following:
(i) In the shadow of a thick cloud the concentration of OH falls
to nearly zero.
(ii) On a global scale the concentration distribution of CO 2 is
about the same whereas the concentration of isoprene varies
from one location to the next.
(iii) There is more than one chemical pathway to the initiation
of night-time chemistry.
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