Hydrogen burning with chlorine

The hydrogen can be used for organic hydrogenation, catalytic reductions, and ammonia synthesis. It can also be burned with chlorine to produce high quaHty HCl and used to provide a reducing atmosphere in some appHcations. In many cases, however, it is used as a fuel. 

An integrated process for producing chlorine dioxide that can consume chlorine (46) involves the use of hydrochloric acid as the reductant. The spent chlorine dioxide generator Hquor is used as feed for chlorate production, and hydrogen gas from chlorate production is burned with chlorine to produce hydrochloric acid. The principal disadvantage in the integrated hydrochloric acid-based processes is that the chlorine dioxide gas contains Y2 mole of chlorine for each mole of chlorine dioxide produced. A partial purification is achieved by absorption in chilled water in which the solubiHty of chlorine is less than chlorine dioxide however, this product stiU contains 10—15% chlorine on the basis of total chlorine and chlorine dioxide. 

Chlorine is a very reactive substance, but less reactive than fluorine. It combines with most elements, to form chlorides, at room temperature or on gentle heating. Hydrogen burns in chlorine, after being ignited, to form hydrogen chloride ... 

The affinity of chlorine for hydrogen is so great that chlorine will react with many compounds containing this element, for example hydrocarbons (a wax taper burns in chlorine). 

Disposal. Moderate amounts of chlorine ttifluoride or other halogen fluorides may be destroyed by burning with a fuel such as natural gas, hydrogen, or propane. The resulting fumes may be vented to water or caustic scmbbers. Alternatively, they can be diluted with an inert gas and scmbbed in a caustic solution. Further information on disposal of halogen fluorides is available (115—118). 

The injury caused by chlorine trifluoride is in part attributed to its hydrolysis products, including chlorine, hydrogen fluoride, and chlorine dioxide. Effects in humans have not been reported but may be expected to be very severe inhalation may cause pulmonary edema, and contact with eyes or skin may cause severe burns. 

Sodium combines with all halogens forming sodium hahdes. The metal ignites with fluorine, forming hydrogen fluoride. Thin metal film reacts readily with chlorine and bromine at ordinary temperatures. Molten sodium burns in chlorine producing sodium chloride. The metal reacts with iodine, only in vapor phase, forming sodium iodide. 

It was shown in Exp. 57 (< ) that chlorine unites easily with metals, forming chlorides, just as oxygen forms oxides. There are many compounds of chlorine and metals, the most common being sodium chloride, which would have been formed in Exp. 57 if sodium, instead of iron and antimony, had been burned in chlorine. It is expensive and inconvenient to prepare large quantities of hydrochloric acid by a synthesis, so the chlorides are allowed to interact with a compound which yields hydrogen easily. Sulphuric acid and sodium chloride are usually used. 

Hydrocyanic acid is most easily prepared from its potassium salt, K(CN), which is obtained principally by the decomposition of the complex double cyanides of iron as we shall soon consider. The acid is also obtained by the hydrolysis of certain glucosides, e.g., amygdalin, in bitter almonds. It is prepared synthetically by reactions to be discussed presently in connection with the constitution of it and its salts. It is a colorless liquid with a characteristic odor and burns with a violet flame. It boils at 26.1 and solidifies to crystals which melt at —14°. It is an extremely strong poison the best antidotes being chlorine and hydrogen dioxide. It is readily absorbed by metallic nickel which is thus used in gas masks for this purpose. It is stable in dry air but in presence of water is readily hydrolyzed yielding ammonia and formic acid as the chief products. 

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