Precautions carbon dioxide

The tap T2 is now closed. The furnace is switched off and the carbon dioxide generator left on until the combustion tube is cold this ensures that the reduced copper spiral, by cooling in carbon dioxide, is main tained in the reduced state. (Despite this precaution it does become spent and should be replaced from time to time. A spent copper spiral leads to high results, but before this takes place there is usually suffici-... 

This tube is connected %vith rubber tubing of about 6 mm. bore to the carbon dioxide Kipp, via a wash-bottle containing sodium carbonate solution (to remove any dilute hydrochloric acid spray). It is very important, when the apparatus is in use, that there should be no constriction or bend in the rubber tube between the tap C and the wash-bottle. If these precautions are taken, a slow, e en, and easily controlled flow of gas can be obtained. 

Bulk storage and use of liquid carbon dioxide hazards and precautions... 

Cadmium, 118 Capture velocity, 408 Carbon dioxide extinguisher, 223 liquid, 261, 278 physical properties, 262 physiological properties, 151, 152, 264, 279 precautions, 152, 262, 280 sources, 151 Carbon monoxide ... 

Use of a steel chisel to open a drum of carbide caused an incendive spark which ignited traces of acetylene in the drum. The non-ferrous tools normally used for this purpose should be kept free from embedded ferrous particles [1], If calcium carbide is warm when filled into drums, absorption of the nitrogen from the trapped air may enrich the oxygen content up to 28%. In this case, less than 3% of acetylene (liberated by moisture) is enough to form an explosive mixture, which may be initiated on opening the sealed drum. Other precautions are detailed [2], Use of carbon dioxide to purge carbide drums, and of brass or bronze non-sparking tools to open them are advocated [3],... 

Procedure Weigh accurately about 0.2 g, dissolve in 50 ml of dimethylformamide, add 2 drops of azo-violet solution and tirate with 0.1 N sodium methoxide to a deep blue end point, taking precautions to prevent absorption of atmospheric carbon dioxide. Perform a blank determination and make any necessary correction. Each ml of 0.1 N sodium methoxide is equivalent to 0.01412 g of C7HnN02. 

In crystallizing and drying salts, it must be remembered that the entire operation is usually carried out in the presence of air. The air contains three constituents that are more or less active as chemical reagents, viz., oxygen, carbon dioxide, and water vapor, and in many cases special precautions must be taken to protect the preparation from atmospheric action. Each case will suggest a somewhat different mode of procedure, and a few typical examples will be used to illustrate these. 

When the apparatus is in use, the bulb of the flask containing the hydriodic aid and the substance is heated in an oil bath at 130°. The methyl iodide is carried over into the absorber by a slow current of dry carbon dioxide, passing in at the side tube. The temperature on the thermometer should not be higher than 35°—40° for methoxyl, and 40° for ethoxyl compounds. At these temperatures no hydriodic acid is distilled over. As a further precaution, the neck of the flask is slanted away from the source of heat. 

The addition of a gas to a reaction mixture (commonly the hydrogen halides, fluorine, chlorine, phosgene, boron trifluoride, carbon dioxide, ammonia, gaseous unsaturated hydrocarbons, ethylene oxide) requires the provision of safety precautions which may not be immediately apparent. Some of these gases may be generated in situ (e.g. diborane in hydroboration reactions), some may be commercially available in cylinders, and some may be generated by chemical or other means (e.g. carbon dioxide, ozone). An individual description of the convenient sources of these gases will be found under Section 4.2. 

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