ENVIRONMENTAL CHEMISTRY
Here we’ll cover three main topics that fall under the broad category of
environmental chemistry: Earth’s atmosphere, the greenhouse effect, and the
causes and effects of acid rain.
The Chemistry of Earth’s Atmosphere
For this test, you should remember that Earth’s atmosphere is about 78 percent
nitrogen, 20 percent oxygen, less than 1 percent argon, and then contains a trace
amount of the following other elements: carbon dioxide, neon, helium, methane,
krypton, hydrogen, nitrous oxide, and xenon. While the test won’t ask you about
the trace elements of the atmosphere, it could ask you about its major
components. The atmosphere is divided into four regions: the troposphere,
which is the layer of the atmosphere that’s closest to the Earth; the stratosphere,
which is the layer above the troposphere; the mesosphere, which is further out;
and then the thermosphere, which is the furthest out of all.
Atmospheric Composition
Nitrogen (N 2 )78%
Oxygen (O 2 ) 20%
Argon (Ar) <1%
Water Vapor variable
Other <1%One molecular component of the atmosphere that you should be aware of is
ozone, O 3 , which you’ve probably heard about before in conjunction with global
warming. Ozone is the result of the collision of elemental oxygen, O, and
diatomic oxygen, O 2 . But how come oxygen can exist in the atmosphere in
elemental form, if it’s supposed to be one of those diatomic molecules? Well, O
is produced in the atmosphere in the following reaction:
O 2 (g)+hγ=2O(g)