Oxygen

.. bon 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.

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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 oxygne German Sauerstoff Italian ossigeno Norwegian oksygen Portuguese oxignio Spanish oxgeno Swedish syre Data 8O15.9994 Atomic Number 8 Atomic Weight 15.9994 Electron Config. 2-2-4 Mechanical Properties Conditions Phase Temp. (K) Pressure (Pa) Density (O2) 1.429 kg/m3 Gas 293.15 101325 Density (O2) 1141 kg/m3 Liquid 90.188 101325 Thermal Properties Conditions 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/g 0 101325 Vaporization Enthalpy (O2) 213.13 J/g 0 101325 Heat Capacity (O2) 918 J/kg-K 298.15 100000 Bibliography Bibliography van Vlack, L.H. (1985), Elements of Materials Science and Engineering, Addison-Wesley (Reading, MA). 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). Science.