Ozone Depletion

Wednesday, May 27, 2009

Ozone Depletion

Just a short intro first, ozone depletion refers to the decrease in ozone levels in the atmosphere :D

the overall cause of ozone depletion is the presence of chlorine-containing source gases (primarily CFCs and related halocarbons). In the presence of UV light, these gases dissociate, releasing chlorine atoms, which then go on to catalyze ozone destruction. The Cl-catalyzed ozone depletion can take place in the gas phase, but it is dramatically enhanced in the presence of polar stratospheric clouds (PSCs).

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Objective of this ACE

a) Describe the volume composition of clean air. (Done)

b) Name some common atmospheric pollutants (CO, CH4, NO,NO2,SO2...)(done)

c) State source of the pollutants as

i) CO from incomplete combustion of carbon-containing substances.

ii) NO,NO2 from lightning activities and internal combustion engines.

iii) SO2 from volcanoes and combustion of fossil fuels.

d) Describe the reactions used in possible solutions to the problems arising from some of the pollutants in b)

i) Redox reaction in catalytic converters to remove combustion pollutants.

ii) Use of calcium carbonate to reduce the effects of acid rain and in flue gas desulfurisation.

e) Discuss some of the effects of these pollutants on health and on the environment

i) Poisonous nature of CO

ii) NO2 and SO2 in formation of acid rain and its effects on respiration, buildings and plants.

iii) NO2, CH4 and unburned hydrocarbons in formation of photochemical smog.

f) Describe importance of ozone layer and the problems involved with the depletion of ozone by reaction with chlorine containing compounds, e.g. CFCs. (Done)

g) Describe carbon cycles in simple terms to include:

i) Process of combustion, respiration and photosynthesis.

ii) How carbon cycle regulate amount of CO2 in atmosphere.

h) State CO2 and CH4 are greenhouse gases and may contribute to global warming, give sources of these gases and discuss the possible consequences of an increase in global warming.

Chemystry - Atmosphere and Environment

Wednesday, May 27, 2009

Ozone Depletion

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