Bromine, atomic weight chlorine compounds

Consider the proper placement of tellurium and iodine in the periodic table, as shown in Figure 1-3. Te has the heavier atomic weight. The chemical properties of tellurium are like those of selenium because both are semi-metallic elements that form compounds like those of sulfur. Iodine resembles bromine because these elements are nonmetallic halogens that form compounds like those of chlorine. Therefore, the order in the table cannot be based solely on atomic weight. 

Prepare a table showing the relation between chlorine, bromine, and iodine. The table should include the atomic weight, physical state, color, typical method of preparation, properties, and analogous compounds. 

Bromine compounds are much more expensive than chlorine compounds and, since the atomic weight of bromine is about twice that of chlorine, the halogen cost incurred in the use of bromine compounds as intermediates is likely to be at least an order of magnitude greater than the cost of the corresponding chlorine compound. Not least for this reason, the synthesis of phosgene from bromine-containing compounds is unlikely to be economically practical and are probably not worthy of development on a purely commercial basis. However, C-Br bonds are more readily cleaved than C-CI bonds, and bromide is readily oxidized back to bromine. 

The vital factor is that any method of automatic selection (and separation) must be able to operate on a large scale, over large volumes of plastics waste, probably conveyorized. Elements of high atomic weight, such as chlorine and bromine can be identified rapidly by means of X-ray fluorescence. This technique could be used to separate compounds containing chlorinated or brominated flame retardants, but to date it has been used in practice only for separating PVC bottles from other plastics. 

Halogen atoms in certain inorganic compounds may be replaced by fluorine by the use of antimony (III) fluoride without a catalyst. In other cases, varying amounts of different kinds of catalysts are required. For example, sometimes the addition of chlorine in the amount of 1 % of the antimony (III) fluoride will suffice. Molecules which are more difficult to fluorinate may require chlorine, bromine, or antimony(V) chloride in quantities amounting to as much as 5% of the weight of antimony (III) fluoride used. 

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