Sulfuric Acid
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: (1) Inco. - Sudbury, (2) Noranda Mines Ltd. -
Welland, and (3)
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 --* 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.