Iron halides elemental halogens

Applications Basic methods for the determination of halogens in polymers are fusion with sodium carbonate (followed by determination of the sodium halide), oxygen flask combustion and XRF. Crompton [21] has reported fusion with sodium bicarbonate for the determination of traces of chlorine in PE (down to 5 ppm), fusion with sodium bisulfate for the analysis of titanium, iron and aluminium in low-pressure polyolefins (at 1 ppm level), and fusion with sodium peroxide for the complexometric determination using EDTA of traces of bromine in PS (down to 100ppm). Determination of halogens in plastics by ICP-MS can be achieved using a carbonate fusion procedure, but this will result in poor recoveries for a number of elements [88]. A sodium peroxide fusion-titration procedure is capable of determining total sulfur in polymers in amounts down to 500 ppm with an accuracy of 5% [89]. 

Between 400 and 430° the hydrogen pressure reaches 1 atm. The melting point (under pressure) is above 800°. Sodium hydride dissolves in fused sodium hydroxide and in fused alkali halides. It is insoluble in liquid ammonia. Water decomposes it immediately and completely to hydroxyl ion and hydrogen. Although sodium hydride is said to be stable in dry oxygen to 230°, traces of elemental sodium present may cause its ignition at lower temperatures. Copper, lead, and iron oxides are reduced by the compound to the free metals. Sulfur dioxide, carbon monoxide, and the halogens are reduced by the hydride to dithionite, formate, and halide ions, respectively. 

The halogen elements are so reactive that the halides of many metals can be prepared by the direct combination of the elements. For example, iron(III) chloride can be prepared by the following reaction ... 

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