The uses of oxygen (from Greek “axis”, acid and “genes”, producer) is a colorless, odorless and tasteless gas (ie colorless, odorless and tasteless), poorly soluble in water, being present in nature under The form of three stable isotopes: oxygen 16 (present in 99.75% of occurrences in the environment); Oxygen 17 (0.37% of occurrences) and oxygen 18 (0.20% of occurrences). It is a little soluble element in water, and at room temperature, its molecule is inert; In the presence, however, of catalytic substances or when receiving heat, reacts with significant part of the chemical elements giving rise to several compounds.
In low atmosphere (i.e., altitudes near the earth’s surface), oxygen is plentiful in its diatomic form (it means that oxygen is found in nature commonly in the form of two isotopes of the same combined type), represented by the formula O2. It is known to be essential for the maintenance of the life of the vast majority of living organisms on the planet. Its density is slightly higher than the air because its atoms are tiny. These atoms have eight electrons, elementary particles of negative charge forming the structure of the same. Because it is too electronegative, the element has a high propensity to join metals (except for halogens) and metals, except for gold and platinum. In forming such combinations, the release of heat occurs – combustion.
The element was first identified in 1772, thanks to the chemist Joseph Priestley, through a calcination experiment of potassium nitrate. It is still recognized as the most abundant element within the globe, accounting for approximately one-fifth of the constitution of pure air and eight-ninths of water weight. Among the various constituents of the soil, it is present in practically all (silicates and carbonates) as well as organic substances. Using its combustion it obtains water vapor and carbonic gas, but, if insufficient amounts are present, the hydrogen burns before the carbon, of which one part brightens the flame, happening to appear in black-form of -smoke.
Oxygen is a chemical element of the group of chalcogens, or group 6A of the periodic table, having as a chemical symbol “O,” composing approximately 20% of the terrestrial atmosphere, making itself present in the composition of all living beings.
Its specific gravity is 1.10 g / cm 3, with a melting point located at about -218.79 degrees Celsius, having an atomic weight of 15.99. Its atomic number is 8, with oxygen being a place among the elements denominated “ametals” in the periodic table of the chemical elements.
In 1775, Lavoisier established the properties of the gas, showed that it existed in air and water, indicated its fundamental role in combustion and gave the name of oxygen to the substance discovered by Scheele and Priestley.
Natural oxygen is a colorless, odorless gas that liquefies at -183 ° C, being the fifth most abundant material on earth and poorly soluble in water. Under specific conditions (in the presence of catalytic substances or when heated), it reacts with numerous other substances, forming various compounds.
Industries and Hospitals
In industry, the raw material used to obtain oxygen gas is atmospheric air. The air (gas mixture with 78% of N2, nitrogen gas, 21% of O2, oxygen gas and 1% of air, argon gas) undergoes compression and cooling until reaching -200 ° C, when it undergoes a fractional distillation, If at -195 o C, N2, -190 o C o Ar, and O2 at -185 o C. Oxygen gas is essential in the respiration of many living beings, besides being used as an oxidizer. Ozone, however, has great importance in the so-called ozone layer, responsible for “filtering” (absorbing) ultraviolet rays from the Sun. It is also used as a disinfectant and in organic reactions. Most of the O2 is used in the manufacture of steel along with iron. Compressed O2 cylinders are used in the industrial area as components for the occurrence of oxy-acetylene solder. They are also widely used in the hospital area.
Oxygen is used mainly in the metal-mechanical industries as combustion of torches for welding and cutting of iron and steel materials; Is also used in the production of synthesis gas, either by oxidation of natural gas or by reduction of water vapor by carbon. It is also used in the production of a wide variety of substances of industrial interest, such as acetylene, acrolein, hydrogen peroxide (hydrogen peroxide), chlorine (by oxidation of HCl), ethylene oxide, phthalic anhydride, The ozone, etc. Other less regular applications include the use of gas in bottles for divers, in hyperbaric tents for therapeutic purposes and as an oxidizer in reaction engines.
Oxygen plays a vital role in the breathing and metabolism processes of living organisms. Probably the only living cells that do not need oxygen are some anaerobic bacteria that get energy from other metabolic processes.
In humans, oxygen is absorbed into the bloodstream in the lungs and then transported to the cells where an intricate exchange process occurs. Complex enzymatic processes oxidize the nutrient compounds within the cell. This intracellular oxidation is the energy source of most animals, especially mammals. The end products are carbon dioxide and water, which are eliminated by the body through the lungs.
Oxygen is useful for the treatment of pneumonia, emphysema, some cardiac disorders, and some other diseases. Hyperbaric oxygen chambers are sometimes used to treat victims of carbon monoxide poisoning or anaerobic bacteria in the respiratory system. Oxygen can potentiate the effects of radiation on cancer cells, so this treatment should be done in hyperbaric oxygen chambers. The use of extremely oxygen-rich environments increases the risk of fire, so strict precautions must be taken.
Oxygen appears as an elemental substance in two allotropic varieties: natural oxygen ( the second constituent of air) and ozone. It also forms a wide variety of compounds and, in the combined state, is the most abundant element in the earth crust (in the form of silica and silicates) and the oceans (in the form of water).
Reference is made to the reaction of oxygen with some transition metal complexes which act as transporters of that substance, i.e., reversibly capture and yield O 2. Some of these complexes constitute prosthetic groups of proteins indispensable to the metabolic process of respiration; Is the case of hemoglobin in red blood cells and certain hemocyanin that are natural carriers of oxygen.