I Must Have That Formula
From Kelly A. Belnick
The Carbon Cycle
:
The different forms and
compounds in which carbon atoms are found are considered chemical reservoirs of
carbon. These reservoirs include atmospheric carbon dioxide, calcium carbonate (in
limestone), natural gas, and organic molecules, to name a few.
: Plants use
carbon dioxide and energy from the sun to form carbohydrates in photosynthesis.
The carbohydrates are consumed by other organisms, and are eventually broken
down, or “oxidized”.
: The process of
respiration. The chemical representation of how carbohydrates are broken down,
or oxidized, thereby releasing energy for use by the consuming organisms. The
carbon used and circulated in photosynthesis represents only a tiny portion of
the available global carbon.
Atmospheric carbon dioxide
levels have increased by 30% since the 1800’s (industrial revolution). This
increase can be explained, primarily, but several human activities. The most
significant of these activities is the burning of fossil fuels.
Nitrogen Cycle
Atmospheric nitrogen is converted to ammonia or ammonium ion by
nitrogen-fixing bacteria that live in legume root nodules or in soil, or
atmospheric nitrogen is converted to nitrogen oxides by lightening.
Ammonia and Ammonium are
oxidized by soil bacteria first to nitrite ions and then to nitrate ions
: After plants
have taken up nitrogen from the soil in the form of nitrate ions, the nitrogen
is passed along the food chain. When those plants and animals die, bacteria and
fungi take up and use some of the nitrogen from the plant/animal protein and
other nitrogen containing molecules. The remaining nitrogen is released as
ammonium ions or ammonia gas. Denitrifying bacteria convert some ammonia,
nitrite, and nitrate back to nitrogen gas, which returns to the atmosphere.
Haber-Bosch Process: A technique for making ammonia from hydrogen and
nitrogen, according to the first equation. To get the reactants, nitrogen gas
is liquefied form air and hydrogen gas is obtained chemically from methane
(natural gas). First natural gas is treated to remove sulfur-containing
compounds; then the present methane is allowed to react with steam. Carbon
monoxide, a product of methane reacting with steam, is converted to carbon
dioxide, which allows for the additional production of nitrogen gas.
Air Pollution Formulas:
:
Impurities such as pyrite or iron pyrite are found in coal, when we burn coal it interacts with atmospheric oxygen to form iron oxide and sulfur dioxide (a primary air pollutant).
:
The primary air pollutant,
sulfur dioxide, is oxidized, once in
the atmosphere, to sulfur trioxide.
:
Sulfur trioxide dissolves it
atmospheric water droplets to form sulfuric acid. Sulfuric acid is a major
component of acid rain. Sulfuric acid is considered a secondary air pollutant
:
The generalized
representation of sulfur oxides, whether it be sulfur dioxide or sulfur
trioxide. The Sulfur oxides are considered primary air pollutants.
:
Molecules of nitrogen and
atmospheric oxygen combine AT VERY HIGH TEMPERATURES to form nitric oxide, a
colorless gas. The high temperatures of natural processes like lightening or
those of the combustion chambers of an engine are effective in causing this
conversion. Nitric oxide is a primary air pollutant
:
Once in the atmosphere,
nitric acid reacts with additional oxygen to form nitrogen dioxide, a red-brown
toxic gas that causes irritation to the eyes and respiratory system
:
Further reaction of nitrogen
dioxide with water can produce nitric acid, another component of acid rain
Photochemical Smog
: Nitrogen
oxide is an essential ingredient of photochemical smog that is produced during
the high temperatures associated with combustion of vehicle’s engines.
: Initial reaction of nitrogen dioxide with sunlight
: The oxygen atom generated from the initial reaction reacts with atmospheric, diatomic oxygen, to form ozone. This is not the good, protective ozone of the stratosphere, this is the polluting ozone of the lithosphere, which traps heat and contributes to thermal inversion.
This simplified
equation represents the key ingredients and products of photochemical smog.
Hydrocarbons (including VOC’s), carbon monoxide, and nitrogen oxides from
vehicle exhausts are irradiated by sunlight in the presence of oxygen gas. The
resulting reactions produce a potentially dangerous mixture that include other
nitrogen oxides, ozone, and irritating organic compounds, as well as carbon
dioxide and water vapor.
Air Pollution Control and Prevention
: Formula that
represents the process of “scrubbing” products of industrial combustion
processes. Sulfur dioxide gas is removes by using an aqueous solution of
calcium hydroxide, also called limewater. The sulfur dioxide reacts with the
limewater to form solid calcium sulfite. Scrubbers that utilize this “wet”
scrubbing method can remove up to 95% of sulfur oxides.
Another process for
scrubbing that utilizes magnesium hydroxide instead of limewater. The sulfur
dioxide dissolves in the water and reacts with the magnesium hydroxide to form
a salt. The magnesium sulfite that is formed can be isolated and heated to
regenerate sulfur dioxide. The recovered sulfur dioxide can be collected and
used as a raw material in other commercial processes.
Acid Rain
: The pH of
rainwater is normally slightly acidic, at about 5.6, due mainly to reaction of
carbon dioxide with water to form carbonic acid.
Other natural events can
contribute to the acidity of precipitation. Volcanic eruptions, forest fires,
and lightning produce sulfur dioxide, sulfur trioxide, and nitrogen dioxide.
These gases can react with atmospheric water in much the same way that carbon
dioxide does to produce sulfurous acid, sulfuric acid, nitric acid and nitrous
acid.
Ozone Formation and Destruction
As sunlight penetrates into
the stratosphere, high-energy UV photons react with oxygen gas molecules, splitting
them into individual oxygen atoms. These highly reactive oxygen atoms are
examples of free radicals; they
quickly enter into chemical reactions that allow them to attain stable
arrangements of electrons. In the stratosphere free radicals can combine with
oxygen molecules to form ozone. A third molecule, typically nitrogen gas or
atmospheric oxygen (represented by M
in the equation), carries away excess energy from the reaction but remains
unchanged.
Each ozone molecule formed
in the stratosphere can absorb a UV photon with a wavelength of less than
320nm. This energy absorption prevents potentially harmful UV rays from
reaching the earth’s surface. The energy also causes the ozone to decomposed,
producing an oxygen molecule and an oxygen free radical. These products can
then carry on the cycle by replacing ozone in the protective stratospheric
layer.
CFC’s (chlorofluorocarbons)
are highly stable molecules in the troposphere, however, high-energy UV photons
in the stratosphere split chlorine radicals from CFC’s by breaking their C-Cl
bond. The freed chlorine radicals are very reactive and can participate in a
series of reaction that destroy ozone by converting it to diatomic oxygen.
Every chlorine radical that participates in the first reaction can later be
regenerated. Thus each chlorine radical acts as a catalyst participating in not
just one, but also an average of 100,000 ozone –destroying reactions. In doing
so, it speeds up ozone destruction but remains unchanged.