Oxygen burning

Oxygen is soluble in both water and alcohol. Contrary to what many people believe, oxygen is NOT combustible (it will not burn), but rather it actively supports the combustion of many other substances. After all, if oxygen burned, every time a fire was lit, all the O in the atmosphere would be consumed ... 

For determination of concentration limits for combustion of fuel gases in air (or oxygen) burning can be conducted either in glass tubes open at one end or in apparatus illustrated in Fig of Ref 6 and Fig 28 of Ref 15, p 120, reproduced here as Fig A. For determination of lower limit, the concentration of combustible gases is decreased until flame ceases to appear, while for determination of upper limits, the concentr ation is increased. 

Figure 3 Abundances after explosive oxygen burning at Mr > 1.67 Mq for the 6 Mq core.

For massive red giants (M > 8 solar masses), one finds they undergo a more spectacular death cycle, with contractions, increases in temperature leading to helium burning, carbon-oxygen burning, silicon burning, and the like with the production of the elements near iron, followed by an explosive end (Fig. 12.8). 

Chlorine is much the most abundant halogen. It is six times more abundant than fluorine and 450 times more abundantthan bromine. This is understood, because both stable Cl isotopes are produced in the main line ofnuclear reactions during oxygen burning in stars. Cl is the 20th most abundant element in the universe, being almost identical in abundance to potassium and 1.5 times more abundant than titanium. But measurements of Cl abundance in stars are few, because it is rare and its emission lines are unfavorable. 

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