Acid Rain

This essay has a total of 3280 words and 17 pages.

Acid Rain


Acid Rain

Written by: Unregistered

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:

1. Inco. - Sudbury
2. Noranda Mines Ltd. - Welland
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 considerabl

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