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_acid rain _
By: mike
Acid Rain Introduction Acid rain has become an environmental concern of global
importance within the last decade. With the increasing environmental awareness
of the "unhealthy" condition of our planet earth the concern about acid rain
has not lessened. In brief, acid rain is rain with pH values of less than 5.6.
When dealing with acid rain one must study and understand the process of
making Sulfuric acid. In this project we will take an in depth look into the
production of sulfuric acid, some of its uses and the effects of it as a
pollutant in our environment. Sulfuric Acid Industry in Ontario Among the many
plants in Ontario where sulfuric acid is produced, there are three major plant
locations that should be noted on account of their greater size. These are:
Inco. - Sudbury Noranda Mines Ltd. - Welland Sulfide - Ontario There are a
number of factors which govern the location of each manufacturing plant. Some
of these factors that have to be considered when deciding the location of a
Sulfuric Acid plant are: a. Whether there is ready access to raw materials; b.
Whether the location is close to major transportation routes; c. Whether there
is a suitable work force in the area for plant construction and operation; d.
Whether there is sufficient energy resources readily available; e. Whether or
not the chemical plant can carry out its operation without any unacceptable
damage to the environment. Listed above are the basic deciding factors that
govern the location of a plant. The following will explain in greater detail
why these factors should be considered. 1) Raw Materials The plant needs to be
close to the raw materials that are involved in the production of sulfuric
acid such as sulfur, lead, copper, zinc sulfides, etc.. 2) Transportation A
manufacturer must consider proximity to transpor-tation routes and the
location of both the source of raw materials and the market for the product.
The raw materials have to be transported to the plant, and the final product
must be transported to the customer or distributor. Economic pros and cons
must also be thought about. For example, must sulfuric plants are located near
the market because it costs more to transport sulfuric acid than the main raw
materials, sulfur. Elaborate commission proof container are required for the
transportation of sulfuric acid while sulfur can be much more easily
transported by truck or railway car. 3) Human Resources For a sulfuric acid
plant to operate, a large work force will obviously be required. The plant
must employ chemists, technicians, administrators, computer operators, and
people in sales and marketing. A large number of workers will also be required
for the daily operation of the plant. A work force of this diversity is
therefore likely to be found only near major centres of population. 4) Energy
Demands Large amounts of energy will also be required for the production of
many industrial chemicals. Thus, proximity to a plentiful supply of energy is
often a determining factor in deciding the plant's location. 5) Environmental
Concerns Most importantly, however, concerns about the environment must be
carefully taken into consideration. The chemical reaction of changing sulfur
and other substances to sulfuric acid results in the formation of other
substances like sulfur dioxide. This causes acid rain. Therefore, there is a
big problem about sulfuric plants causing damage to our environment as the
plant is a source of sulfur emission leading to that of acid rain. 6) Water
Supplies Still another factor is the closeness of the location of the plants
to water supplies as many manufacturing plants use water for cooling purposes.
In addition to these factors, these questions must also be answered: Is land
available near the proposed site at a reasonable cost? Is the climate of the
area suitable? Are the general living conditions in the area suitable for the
people involved who will be relocating in the area? Is there any suggestions
offered by governments to locate in a particular region? The final decision on
where the sulfuric acid plant really involves a careful examination and a
compromise among all of the factors that have been discussed above. Producing
Sulfuric Acid Sulfuric acid is produced by two principal processes-the chamber
process and the contact process. The contact process is the current process
being used to produce sulfuric acid. In the contact process, a purified dry
gas mixture containing 7-10% sulfur dioxide and 11-14% oxygen is passed
through a preheater to a steel reactor containing a platinum or vanadium
peroxide catalyst. The catalyst promotes the oxidation of sulfur dioxide to
trioxide. This then reacts with water to produce sulfuric acid. In practice,
sulfur trioxide reacts not with pure water but with recycled sulfuric acid.The
reactions are: 2SO2 + O2 * 2SO3 SO3 + H2O * H2SO4 The product of the contact
plants is 98-100% acid. This can either be diluted to lower concentrations or
made stronger with sulfur trioxide to yield oleums. For the process, the
sources of sulfur dioxide may be produced from pure sulfur, from pyrite,
recovered from smelter operations or by oxidation of hydrogen sulfide
recovered from the purification of water gas, refinery gas, natural gas and
other fuels. Battery Acid Industry Many industries depend on sulfuric acid.
Among these industries is the battery acid industry. The electric battery or
cell produces power by means of a chemical reaction. A battery can be primary
or secondary. All batteries, primary or secondary, work as a result of a
chemical reaction. This reaction produces an electric current because the
atoms of which chemical elements are made, are held together by electrical
forces when they react to form compounds. A battery cell consists of three
basic parts; a positively charged electrode, called the cathode, a negatively
charged electrode, called the anode, and a chemical substance, called an
electrolyte, in which the electrodes are immersed. In either a wet or dry
cell, sufficient liquid must be present to allow the chemical reactions to
take place. Electricity is generated in cells because when any of these
chemical substances is dissolved in water , its molecules break up and become
electrically charged ions. Sulfuric acid is a good example. Sulfuric acid,
H2SO4, has molecules of which consist of two atoms of hydrogen, one of sulfur
and four oxygen. When dissolved in water, the molecules split into three
parts, the two atoms of hydrogen separate and in the process each loses an
electron, becoming a positively charged ion (H+). The sulfur atom and the four
atoms of oxygen remain together as a sulfate group (SO4), and acquire the two
electrons lost by the hydrogen atoms, thus becoming negatively charged
(SO4--). These groups can combine with others of opposite charge to form other
compounds. The lead-acid cell uses sulfuric acid as the electrolyte. The
lead-acid storage battery is the most common secondary battery used today, and
is typical of those used in automobiles. The following will describe both the
charging and discharging phase of the lead-storage battery and how sulfuric
acid, as the electrolyte, is used in the process. The lead storage battery
consists of two electrodes or plates, which are made of lead and lead peroxide
and are immersed in an electrolytic solution of sulfuric acid. The lead is the
anode and the lead peroxide is the cathode. When the battery is used, both
electrodes are converted to lead sulfate by the following process. At the
sulfate ion that is present in the solution from the sulfuric acid. At the
cathode, meanwhile, the lead peroxide accepts two electrons and releases the
oxygen; lead oxide is formed first, and then lead joins the sulfate ion to
form lead sulfate. At the same time, four hydrogen ions released from the acid
join the oxygen released from the lead peroxide to form water. When all the
sulfuric acid is used up, the battery is "discharged" produces no current. The
battery can be recharged by passing the current through it in the opposite
direction. This process reverses all the previous reactions and forms lead at
the anode and lead peroxide at the cathode. Proposed Problem i) The
concentration of sulfuric acid is 0.0443 mol/L. The pH is: No. mol of hydrogen
ions = 0.0443 mol/L x 2 = 0.0886 mol/L hydrogen ions pH = - log [H] = - log
(0.0886) = - (-1.0525) = 1.05 Therefore, pH is 1.05. ii) The amount of base
needed to neutralize the lake water is: volume of lake = 2000m x 800m x 50m =
800,000,000 m3 or 8x108 m3 since 1m3=1000L, therefore 8x1011 L 0.0443 mol/L x
8x1011 = 3.54 x 1010 mol of H2SO4 in water # mol NaOH = 3.54 x 1010 mol H2SO4
x 2 mol NaOH 1 mol H2SO4 = 7.08 x 1010 mol of NaOH needed Mass of NaOH = 7.08
x 1010 mol NaOH x 40 g NaOH 1 mol NaOH = 2.83 x 1012 g NaOH or 2.83 x 109 kg
NaOH Therefore a total of 2.83 x 1012 g of NaOH is needed to neutralize the
lake water. iii) The use of sodium hydroxide versus limestone to neutralize
the lake water: Sodium hydroxide: Sodium hydroxide produces water when
reacting with an acid, it also dissolves in water quite readily. When using
sodium hydroxide to neutralize a lake, there may be several problems. One
problem is that when sodium hydroxide dissolves in water, it gives off heat
and this may harm aquatic living organisms. Besides this, vast amounts of
sodium hydroxide is required to neutralize a lake therefore large amounts of
this substance which is corrosive will have to be transported. This is a great
risk to the environment if a spill was to occur. The following equation shows
that water is produced when using sodium hydroxide. 2NaOH + H2SO4 * Na2 SO4 +
2H2O Limestone: Another way to neutralize a lake is by liming. Liming of lakes
must be done with considerable caution and with an awareness that the aquatic
ecosystem will not be restored to its original pre-acidic state even though
the pH of water may have returned to more normal levels. When limestone
dissolves in water it produces carbon dioxide. This could be a problem since a
higher content of carbon dioxide would mean a lowered oxygen content
especially when much algae growth is present. As a result, fish and other
organisms may suffer. Limestone also does not dissolve as readily as sodium
hydroxide thus taking a longer period of time to react with sulfuric acid to
neutralize the lake. The equation for the neutralization using limestone is as
follows: Ca CO3 + H2SO4 ÄÄ* CaSO4 + H2O. iv) The effect of the Acid or
excessive Base on the plant and animal life: You will probably find that there
aren't many aquatic living organisms in waters that are excessively basic or
acidic. A high acidic or basic content in lakes kill fishes and other aquatic
species. Prolonged exposure to acidic or excessively basic conditions can lead
to reproductive failure and morphological aberration of fish. A lowered pH
tends to neutralize toxic metals. The accumulation of such metals in fish
contaminates food chains of which we are a part as these metals can make fish
unfit for human consumption. Acidification of a lake causes a reduction of the
production of phytoplankton (which is a primary producer) as well as in the
productivity of the growth of many other aquatic plants. In acidic conditions,
zooplankton species will probably becompletely eliminated. In addition,
bacterial decomposition of dead matter is seriously retarded in acidified lake
waters. Other effects of acidic conditions arean overfertilization of algae
and other microscopic plant lifecausing algae blooms. Overgrowth of these
consumes quickly most of the oxygen in water thus causing other life forms to
die from oxygen starvation. When there are excessive base or acid in waters,
not only do aquatic organisms get affected but animals who depend on aquatic
plants to survive will starve too, since few aquatic plants survive in such
conditions. Therefore each organism in the aquatic ecosystem is effected by
excessive basic or acidic conditions because anything affecting one organism
will affect the food chain, sending repercussions throughout the entire
ecosystem. v) The factors that govern this plant's location, if this plant
employs 40% of the towns people: The major factors that would govern this
plant's location would be whether there is ready access to raw materials;
whether the location is close to major transportation routes; whether energy
resources are readily available and if there is an adequate water supply in
the area. Since this plant would employ 40% of the towns people, the plant
should be close to the town while still far enough so that in case of any
leakage of the plant, the town will be within a safe distance of being
severely affected. The factor of whether the general living conditions in the
area are suitable for the workers should also be considered as well.
Additional Comments a) The situation of pollution in the Great Lakes and
process being used to start cleaning it up-comments: Everyday, roughly 3630
kilograms of toxic chemicals enter the lakes, nearby land and air. Pollution
of the Great Lakes has become an increasingly serious problem. Just in Lake
Ontario, hundreds of thousands of tons of contaminants have been deposited
over the years. These include DDT, PCBs, mercury, dioxins and mirex, a
pesticide. About 4.6 million people depend on Lake Ontario alone for drinking
water. The environmental problem of greatest concern to Lake Ontario
neighbours is water-discharged toxic chemicals and industrial air pollutants.
Not only is this occurring in Lake Ontario but the other Great Lakes as well.
The lakes probably have all these poisonous chemicals in them: salts drained
from urban streets, coliform bacteria from the sewage civilization plus a
selection of substances such as phosphorus, polychlorinated biphenyls and
heavy metals. It is reported that the toxic chemicals in the Great Lakes basin
are a health risk linked to brain damage, birth defects and cancer. All the
predator species at the top of the food chain have shown health problems as a
result of toxic chemicals building up in their bodies. Chemicals that exist in
low levels in the air and water accumulate as they move up through the food
chain. At present 35 million humans who live around the horridly polluted five
Great Lakes face increasing health risks from environmental contaminants.
Millions of people in the Great Lakes are exposed to hazardous chemicals. They
drink them in the contaminated water, eat them concentrated in the flesh of
the fish and breathe them in the air. Mulroney said that the risks are too
high and that we cannot afford any more risks. He said pollution problems
could be fought under a three-stage plan over the next decade: 1) A "toxic
freeze" banning new polluters from putting up pipes or smokestacks in the
region 2) An attack on "non-point sources" of pollution, such as run-off from
streets and farms where groundwater is loaded with pesticides. 3) A crackdown
on existing polluters when their smoke and sewer-discharge permits come up for
renewal, requiring them to scale down their pollution. Consumers can also help
by demanding pesticide-free food. International agreements have been made to
clean up the Great Lakes. Canada's federal Conservative government has
announced in 1989 to spend $125 million over five years on Great Lakes
cleanup. By one estimate, it may cost as much as $100 billion to retrieve the
purity of the Great Lakes once had. b) The treatment of water for drinking and
water purifiers one can purchase-comments: As the people's uncertainty to the
quality of our drinking water increases, many more people are buying water
treatment devices and purifiers. Even though most treated tap water is fit to
drink, people are losing faith in the government to keep it that way.
therefore purifier leave become increasingly popular among consumers. However
each of the most popular cleansing methods has some disadvantages. Many
filters use some form of "activate" carbon. However, few carbon filters alone
do a very good job of reducing heavy metals such as lead even though the
smallest sink-tap charcoal strainer will make cloudy water look and taste a
bit better. Distillation units turn water to steam and recondense it to a
cleaner state. This process has its disadvantages, too for they can also pass
along harmful chemicals with low boiling points into the water. Another water
treatment device is the reverse-osmosis device which uses sophisticate
membranes to separate pure water from impure. Even though this is effective,
three gallons of water for every good one produced is generally wasted. Some
machines zap germs with lethal doses of ultraviolet light. A specific example
of a water filter is the NSA 3000HM high density filter. This filtration unit
is designed to remove lead, iron, sulfur and manganese from your drinking
water supply. Still another example is a water treatment system called the NSA
Bateriostatic water treatment system. This system removes chlorine, bad taste
and odours, reduces undissolved particles (sediment, discolouration, etc.) and
inhibits bacteria growth. Each of these processes can reduce impurities in
your water supply and many machines as suggested by the above examples combine
several approaches. c) BRIEF OUTLINE OF THE KEY EVENTS IN THE U.S.-CANADA
RELATIONS WITH RESPECT TO CLEANING UP THE GREAT LAKES: 1972: the U.S. chairman
of the International Joint Commission, announced to study to determine the
polluting effects on the Great Lakes urban development and agricultural land
use, find remedies and estimate cleanup costs; Canada and the United States
signed a Great Lakes Quality Agreement. 1974: Canadians say the cleanup
financed by Washington is already running far behind the schedule envisaged
when the agreement was signed. 1978: Canada and the United States agreed to
the goal of zero discharge of pollution. 1987: the goal made in 1978 is made
again, this means both countries agreed to work toward completely eliminating
persistent toxic pollutants, not just the amount being discharged by industry;
Mulroney also proposed that the U.S. slash industrial sulfide and nitrogen
oxide emissions by half before 1994. The Canada-U.S. International Joint
Commission meets every two years to discuss pollution and other issues
concerning the Great Lakes, At present, they are making a ten-year headline
for the Great Lakes to be cleaned up.
_Bibliography _
Bibliography Encyclopedias Collier Encyclopedia, volume 3, U.S.A.: MacMillan
Educational Company, New York, 1984. Encyclopedia of Industrial Chemical
Analysis, volume 18, U.S.A.: John Wiley &Sons, Inc, 1973. Science &Technology
Illustrated: The World Around U.S., Volume 3, U.S.A: Encyclopedia Britannica
Inc, 1984. Articles Cleaning Up By Cleaning Up Newsweek: Feb. 27, 1989.
"Deadline Urged for Cleanup of Great Lakes", Toronto Star, Oct. 14, 1989.
"Great Afflictions of the Great Lakes", The Globe and Mail, Oct. 14, 1989.
"Great Lakes Pollution as a Political Issue", The Globe and Mail, Oct. 16,
1989. "N.Y. Accused of Overlooking Pollution in Lake", Toronto Star, Feb. 26,
1990. "Pact On Great Lakes Cleanup Not Working, Greenpeace Says", Globe and
mail, July 19, 1989. "The Clean Water Industry Grows on Fear, Uncertainty",
Toronto Star, Jan. 28, 1990. "Information Scarce On Great Lakes Chemicals",
The Globe and Mail, Oct. 14, 1989. Others Countdown Acid Rain, Facts: Ministry
of the Environment, 1989. Sanderson, Kimberly, Acid Forming Emissions, Canada:
Environment Council of Edmonton, Alberta, 1984. The New How It Works, volume
2, Westport Connecticut; H.S. Stuttman Inc., 1987.
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