Halogen-hydrogen flames

Day, M. J., D. V. Stamp, K. Thompson, and G. Dixon-Lewis. 1971. Inhibition of hydrogen-air and hydrogen-nitrous oxide flames by halogen compounds. 13th Symposium (International) on Combustion Proceedings. Pittsburgh, PA The Combustion Institute. 705-21. 

The next more complicated system which yields laboratory flames is that of hydrogen-halogens. In practice, flames can be obtained from hydrogen mixed with bromine, chlorine, or fluorine. No hydrogen-iodine flame has been observed. These systems are identical in their chemistry and the failure to realize a hydrogen-iodine flame is connected with the dominance of the direct molecular reaction over the atom-catalyzed reaction which characterizes the other flames. This occurs because of the low reactivity of the iodine atom. 

The hydrogen-oxygen flame is more complex than the hydrogen-halogen system because oxygen is divalent and the intermediate radicals OH and HO2 must be considered as well as possible reactions involving H2O2 and O3. 

The gas reacts vigorously with the halogens. When mixed with chlorine a flame is produced and arsenic and hydrogen chloride are formed 12 with excess of chlorine arsenic trichloride is produced, and in the presence of water arsenious and arsenic acids result. Bromine13 reacts similarly, the oxidation in the presence of water to arsenic acid being quantitative.14 With liquid chlorine, arsine reacts at temperatures as low as -140° C., forming reddish products, apparently containing... 

Analogous experiments with mixtures of identical combustion temperature containing various excess amounts of carbon monoxide showed that the flame velocity is proportional to [CO ]1/2, where [CO ] is the carbon monoxide concentration in the reaction zone. From this it follows that the chemical reaction in a flame is first order in carbon monoxide. The role of water in the combustion of carbon monoxide is well known. Analysis of available data shows that the flame velocity is proportional to [H20]1//2, i.e., the reaction is first order in water vapor content. The influence on combustion of such flegmatizers as CC14 may be ascribed to the binding of hydrogen by halogen with the formation of a molecule of HC1, which is dissociable only with difficulty. However, the latest experiments by Kokochashvili in our laboratory show that the influence of the... 

---