Oxygen Essay, Research Paper

Oxygen is one of the 92 known elements. An element is a substance that cannot be decomposed into a simpler substance by any simple means. Each of the 92 naturally occurring elements are therefore one of the fundamental materials from which everything in the Universe is made.

The History of Oxygen

On August 1,1774, Joseph Priestley examined the effect of intense heat on mercuric oxide. He noted that an air or gas was readily expelled from the specimen. To his surprise a candle burned in this with a remarkably vigorous flame. He called this new substance dephlogisticated air, in terms of the current chemical theory of combustion. On a visit to Paris in 1775 he related his discovery directly to Antoine Lavoisier. Immediately Lavoisier checked the results by accurate experiments and found that Priestley’s dephlogisticated air actually combined with metals and other substances. Since some of the compounds he formed produced acids he regarded the dephlogisticated air as a acidifying principle and called it oxygen, derived from the Greek words for ?sour? and ?I Produce?.

From his experiments Lavoisier recognized that air was composed of two main constituents: vital air or oxygen and azote (Greek for lifeless-now called nitrogen) which would not support life or combustion. From these facts Lavoisier developed the modern theory of combustion, and thus laid the foundation of modern chemistry.

Forms of Oxygen

Oxygen comes in a variety of forms. One of the more deadly forms of Oxygen is Ozone, O3.

Ozone (O3), named for the Greek word for “smell,” is a poisonous, colorless and tasteless gas with a distinctive strong smell. Molecules of ozone are probably the source of the smell that can be detected close to working electrical equipment such as motors and TVs. If a vehicle with a catalytic converter is started cold, ozone can be detected in the exhaust fumes. Most ozone is found high in the atmosphere in a region of the stratosphere called the ozone layer. Here ozone performs a vital life-protecting role, absorbing the ultraviolet rays of the sun that would be harmful to both plant and animal life.

Ozone is usually prepared by passing a silent electric discharge through oxygen. Because of its powerful oxidizing properties ozone is widely used for sterilizing water and for air purification. It also is applied in organic chemistry in ozonolysis, which is the reaction of ozone with unsaturated compounds such as the hydrocarbon ethylene.

Oxides are a large and important class of chemical compounds in which oxygen is combined with another element. Nearly all the elements form oxides, which vary in properties according to their composition. Metal oxides are crystalline solids that contain a metal cation and the oxide anion, O-2. They typically react with water to form bases or with acids to form salts. Calcium oxide (CaO), for example, reacts with water to form calcium hydroxide [Ca(OH2)], a strong base, and with hydrochloric acid to form calcium carbonate (CaCl2), a salt.

Nonmetals oxides are volatile compounds in which the oxygen atoms are linked covalently to the nonmetal atom. They react with water to form acids or with bases to form salts. Thus, sulfur trioxide (SO3) reacts with water to form sulfuric acid (H2SO4), a strong acid, and with sodium hydroxide to form sodium sulfate (Na2SO4), a salt. Amphoteric oxides contain oxygen along with cations such as aluminum, tin, or zinc; they may combine with either acids or bases to form salts. Aluminum oxide (Al2O3), for example, reacts with hydrochloric acid to form aluminum chloride (AlCl3) and with sodium hydroxide to form Sodium Aluminate (NaAlO2).

Certain organic compounds react with oxygen or other oxidizing agents to produce substances called oxides. Thus, amines, phosphines, and sulfides form amine oxides, phosphine oxides, and sulfoxides, respectively, in which the oxygen atom is covalently bonded to the nitrogen, phosphorus, or sulfur atom. The so-called olefin oxides are cyclic ethers.

Another place where oxygen is found is the atmosphere. The Atmosphere surrounding the earth is a mechanical mixture of gases. The most important of these gases are oxygen, nitrogen, and carbon dioxide. The relative proportions of these gases in the atmosphere are found to be remarkably constant.

Oxygen is essential to life. It is odorless, colorless, tasteless, and slightly heavier than air. The chief commercial source of oxygen is the atmosphere. Oxygen may be separated from the mixture of gases that make up the atmosphere. This is done by physical means, by subjecting air to very high pressures and low temperatures until a point is reached where it passes form the gaseous into the liquid state. The liquid air is then allowed to warm slightly, so that nitrogen, which has a lower boiling point than oxygen, evaporates off. At a slightly higher temperature, almost pure oxygen is reconverted into gas, which is pumped into steel cylinders and thus stored in compressed form.

It may be interesting to note that oxygen was first prepared by heating certain metal oxides, including mercury oxide. Oxygen in the air is kept constant by the balance between the actions of plants and animals. Oxygen also supports combustion.

Uses

In our busy world of today, we are using oxygen for many different things and in many different ways.

One of the ways is oxygen therapy where oxygen is used to cure stress or to calm people down. Oxygen Therapies have been around for many years, and range from the use of hydrogen peroxide to Ozone Therapy. Ozone is by far the most aggressive of all the Oxygen Therapies, and perhaps the most controversial. Accepted in 16 countries, Ozone Therapy has met with much resistance in the United States. The FDA does everything in its power to quell the acceptance of it, but it is slowly gaining acceptance. The FDA would like people to believe that Ozone is a form of pollution found in the air, but Ozone in relation to Oxygen Therapies is produced using high quality Ozone generators from Medical Grade Oxygen. The main thrust behind the suppression of Ozone appears to be pharmaceutical based. Only Ozone delivery methods are paten able, so there is not much money to be gained by pursuing it clinically. On the other hand, the money that the pharmaceutical companies stand to lose because of Ozone is where the problem begins. If Ozone Therapy were to eliminate the use of even 50% of pharmaceutical drugs, billions of dollars are at stake.

Another way is, of course, respiration. The term “respiration” refers to the gaseous interchange between an organism and its environment, namely taking in oxygen and getting rid of carbon dioxide. Inhalation (the breathing of air into the lungs and the diffusion of oxygen form the inspired air across the pulmonary membrane in the blood stream), together with exhalation (the passage of carbon dioxide from the blood into the lungs and the breathing out of air), constitutes only one phase of respiration. A second phase of it is the transportation of oxygen by the blood from the lungs to the tissues and of carbon dioxide from the tissues to the lungs. A third phase is the absorption (passage by diffusion) of oxygen into the tissue cells and tissue use of oxygen (the oxidative and other respiratory processes with in the tissues cells whereby energy is liberated).

“External respiration” involves the exchange of gases between the circulation blood and the air. For this exchange to take place, a person needs a large moist surface where air and blood can come in close contact. The lungs provide area for diffusion. And of course there must be a passageway state air expelled from the lungs.

“Internal respiration,” on the other hand, involves the exchange of gases between the circulating blood and the various tissue cells as they use oxygen and produce waste carbon dioxide. When the blood reaches the capillaries, the oxygen molecules are forced through the capillary wall because the tension outside the wall is lower, oxygen then moves onto the tissue cells. The tension of oxygen in the plasma rapidly falls, and this leads to a dissociation of oxygen from combination with hemoglobin diffuse out of the red blood cells into the plasma, and hence through the capillary wall. The average amount of oxygen gives up to the tissue cells all over the body from each 100cc. of blood is about 5cc. In other words, the tissue cells of an adult normally utilize 250cc. of oxygen per minute. Even after the tissues have received all their requirements, the venous blood is still 70-75% saturated with oxygen, under ordinary circumstances. The body needs oxygen to release energy from food.

Through respiration, body cells take in oxygen and use it to turn the sugar in food into energy which is involved in every activity that occurs within the body. For example, the beating of the heart the building and repair of tissue and brain activity cannot occur without energy. The energy needs of the body must take precedence over all others. Without energy there is cell disorganization and death. Every person must be supplied with oxygen continually, since oxygen cannot be stored in the body. What occurs when the body does not get enough oxygen to supply its needs? Whatever the reasons may be, the person usually has dyspnea (difficult breathing), rapid pulse, pallor, and hyperpnoea (increase in breathing), often he also has cyanosis (bluish discoloration of the skin). In hemorrhage, there is “air hunger,” a kind of gasping for breath.

Yet another way is combustion, where oxygen can be used to fuel a flame and increase its heat. Oxygen has two fundamentally important properties: it supports combustion and it supports life. The first commercial use of oxygen was for limelight illumination in theaters, but oxygen has been used in welding and medicine since the turn of the century and in steel production since the 1950s. Iron and steel producers need oxygen to accelerate melting and to remove impurities the refining process. Steel mills consume oxygen on a massive scale. A modern plant can use in excess of 2,000 tons per day, and it is for this reason that supplies to this market are usually piped directly form an air separation unit (ASU)plant.

Oxygen is also used by many other industries in a variety of oxidation processes. Mixed with fuel gases, oxygen provides a heat source for many welding, cutting and metal fabrication processes. Oxygen-fed furnaces and burners are also found in non-ferrous metal plants, brick making kilns, pulp and paper mills and in glass manufacturing. Oxygen-enhanced combustion increases productivity and help to reduce harmful combustion by-products. Combustion is the process of burning. More specifically, it is a rapid chemical reaction that releases energy. An example of a combustion reaction is the burning of coal, where the main reaction involves converting carbon and oxygen to carbon dioxide. For combustion to occur, fuel, and oxidizer, and an ignition stimulus are required. Fuels can be divided into three categories, solid, liquid and gas. Examples of solid fuels include filter paper, Plexiglas, wood, and coal. Liquid fuels include materials like kerosene and gasoline, while materials such as methane and hydrogen constitute gaseous fuels. Oxidizers can similarly be solid, liquid, or gaseous. Air, which contains gaseous oxygen as one of its components, is a particularly common oxidizer. An electrical spark is an example of a ignition stimulus. A vital process that has been the subject of vigorous scientific research for over a century, combustion accounts for approximately 85% of the world’s energy production – and a significant fraction of the world’s atmospheric pollution as well. Combustion plays a key role in ground transportation, spacecraft and aircraft propulsion, global environmental heating, materials processing, hazardous waste disposal through incineration, as well as many other areas. Despite this, there is limited understanding of many fundamental combustion processes, for example how pollutants are formed during these processes?

The manufacture of oxygen

Originally oxygen was prepared on an industrial scale by the Brin process. Barium oxide (BaO) is heated in compressed air to form barium peroxide (BaO*SUB2* sub*). The temperature and pressure are reduced and the peroxide reverts to the monoxide. During the process, oxygen is released.

2BaO2 –* 2BaO –* O2

barium peroxide–* barium oxide–* oxygen

Today a little oxygen is prepared by the electrolytic decomposition of water, but the principal method, of production is the liquefaction and fractional distillation of air.

Name

Greek oxy genes meaning ‘acid forming’

Name in OtherLanguages Croatian Kisik

Danish oxygen

Dutch zuurstof

Finnish happi

French oxyg?ne

German Sauerstoff

Italian ossigeno

Norwegian oksygen

Portugueseoxig?nio

Spanish ox?geno

Swedish syre

Data

8O15.9994Atomic Number8

Atomic Weight15.9994

Electron Config.2-2-4

Mechanical PropertiesConditions

PhaseTemp. (K)Pressure (Pa)

Density (O2)1.429 kg/m3Gas 293.15 101325

Density (O2)1141 kg/m3Liquid 90.188 101325

Thermal PropertiesConditions

Temp. (K)Pressure (Pa)

Melting Temperature (O2)54.36 K 101325

Boiling Temperature (O2)90.2 K 101325

Critical Temperature (O2)154.59 K

Fusion Enthalpy (O2)13.8 J/g0 101325

Vaporization Enthalpy (O2)213.13 J/g0 101325

Heat Capacity (O2)918 J/kg-K298.15 100000

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Brady, G.S., et al. (ed.) (1997), Materials Handbook, 14th ed., McGraw-Hill (New York).

Gere J.M., Timoshenko, S.P. (1984), Mechanics of Materials, 2nd ed., Brooks/Cole (Monterey, CA).