Oxygen gas

Oxygen gas of enrichments from 10 to 99% oxygen-18 and up to 12% oxygen-17 are commercially available (YEDA, Research and Development Corp.). 

Gas with a lower concentration (1.0-10% oxygen-18) can be obtained by the following methods depending on the quantity of gas required. 

When large quantities of oxygen gas are needed the best method is the electrolysis of 0 -enriched water. An investment of several milliliters of water is needed as the hold up in the electrolysis cell. To reduce this, cells have been designed with the minimum internal volume consistent with reasonable rates of oxygen evolution. An apparatus for microelectrolysis of water has been described by Bentley (1949b). Another simple design is shown in Fig. 1. Since such cells often have to feed gas to a vacuum line, some special method has to be used which 

The source of current can be a rectifier-transformer or a battery. The electrolyte is a 20% aqueous solution of sulfuric acid, a solution of sodium sulfate, or better, aqueous sodium hydroxide made by dissolving pure metallic sodium in 0 -enriched water, to give about a 4 iV solution. 

The oxygen evolved should be dried to remove traces of 0 -enriched water by passing it through a dry ice-acetone cooled trap. The vacuum line permits both the storage of oxygen gas and various syntheses. 

Oxygen is essential for human life as each cell requires a constant supply to stay alive. Our bodies depend upon three main carriers of oxygen from the outside air into the cell processes. Oxygen gas is not very soluble in water and equally poorly soluble in the blood and body fluids. For example, one litre of blood only carries 2.7 ml of oxygen. This would be totally inadequate to support life. Arterial blood carries 2.7 ml O2 per litre of blood dissolved in it and 204.7 ml chemically combined with haemoglobin. 

Factors that influence the release of oxygen from oxyhaemoglobin are partial pressure or demand for oxygen at the site (for metabolism), pH, carbon dioxide 

There are certain bacteria that like an oxygen rich atmosphere and others do not. Cohen, in New Scientist,3 summarized research that showed that some flesh eating bacteria, when injected into some cancers, consumed the dangerous cells and rendered them inactive. The critical thing is to choose bacteria that consume cancer cells in the absence of air inside the tumours but die as they reach the more oxygen-rich outside. This is even more effective if used in combination with chemotherapy. These treatments have worked in animals but it will be some time before they will be tested on human tumours. 

To thin the blood and take up any harmful free radicals (2) 

Look at the following chemical reactions and say what has been oxidized and what has  

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Many factors other than current influence the rate of machining. These involve electrolyte type, rate of electrolyte flow, and other process conditions. For example, nickel machines at 100% current efficiency, defined as the percentage ratio of the experimental to theoretical rates of metal removal, at low current densities, eg, 25 A/cm. If the current density is increased to 250 A/cm the efficiency is reduced typically to 85—90%, by the onset of other reactions at the anode. Oxygen gas evolution becomes increasingly preferred as the current density is increased. 

The most outstanding property of the perchlorates is their oxidising abiUty. On heating, these compounds decompose into chlorine, chlorides, and oxygen gas. Aqueous perchlorate solutions exhibit Httle or no oxidising power when dilute or cold. However, hot concentrated perchloric acid is a powerful oxidizer and whenever it contacts oxidizable matter extreme caution is required. The acidified concentrated solutions of perchlorate salts must also be handled with caution. Ammonium perchlorate [7790-98-9] (AP) is one of the most important perchlorates owing to its high (54.5%) O2 content and the... 

In oxygen steelmaking, 99.5% pure oxygen gas is mixed with hot metal, causiag the oxidation of the excess carbon and siHcon ia the hot metal and thereby produciag steel. In the United States, this process is called the basic-oxygen process (BOP) (4,9,10). The first U.S. commercial iastallation began operation in 1955. 

The oxygen reaction is quite complex. Complete reduction from oxygen gas to hydroxide ion involves four electrons and requires several steps. Initially, oxygen is reduced to peroxyl ion [14691-59-9]... 

Some battery designs have a one-way valve for pressure rehef and operate on an oxygen cycle. In these systems the oxygen gas formed at the positive electrode is transported to the negative electrode where it reacts to reform water. Hydrogen evolution at the negative electrode is normally suppressed by this reaction. The extent to which this process occurs in these valve regulated lead —acid batteries is called the recombination-efficiency. These processes are reviewed in the Hterature (50—52). 

Another application is in tire oxidation of vapour mixtures in a chemical vapour transport reaction, the attempt being to coat materials with a tlrin layer of solid electrolyte. For example, a gas phase mixture consisting of the iodides of zirconium and yttrium is oxidized to form a thin layer of ytnia-stabilized zirconia on the surface of an electrode such as one of the lanthanum-snontium doped transition metal perovskites Lai j.Srj.M03 7, which can transmit oxygen as ions and electrons from an isolated volume of oxygen gas. 

Vhen oxygen gas is bubbled too long, the solution becomes viscous and sejfaration of solid mass occurs, but the mass dissolves with addition of 1,2-nenzenediamme. 

Do not nip/kink the hose to cut off the oxygen supply while changing torches - always use the isolation valve Do not leave blowpipes or torches inside a confined space during breaks Wherever possible locate the cylinder outside the confined space Do not use oxygen gas as a source of pressure in place of compressed air... 

Chemical Reactivity - Reactivity with Water Reacts slowly with water at room temperature to form limewater and oxygen gas Reactivity with Common Materials Heavy metals and dirt can accelerate decomposition to lime and oxygen. The reaction is not explosive Stability During Transport Stable Neutralizing Agents for Acids and Caustics Flush with water Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Oxygen gas first produced industrially (from BaOi) by A. Brin and L. W. Brin s Oxygen Company. 

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