lightsandsirens5
Forum Deputy Chief
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I think it has been said before, but this way of saying it helped me out.
Although they are slightly different, think of combustion as oxidation. (Actually it is, but through a different, rapid, exothermic reaction.) So, in our minds now: Combustion=Oxidation.
So we have the equation: (fuel) + O2 = By products...often H2O vapor in the case of Hydrogen containing substances (Most fuels) and CO2 in Carbon containing substances (Largely the class A type fires)
In the case of Hydrogen combustion we get:
2x H2+O2 = 2x H2O (Technically 2x H2+O2 <=> 2x H2O)
So we see that the rapid, complete oxidation of Hydrogen (catalyzed and driven by heat) results in the formation of water. Water is essentially a "by product" of the combustion (rapid, exothermic oxidation) of Hydrogen. Because Hydrogen is now already oxidized, it is no longer available to its environment, neither is the Oxygen that oxidized it. Of course the reaction will run in reverse, given the right conditions. But simply the heat and chemical chain reactions caused by, say a structure fire, are just not enough to drive the equation to the left.
Although they are slightly different, think of combustion as oxidation. (Actually it is, but through a different, rapid, exothermic reaction.) So, in our minds now: Combustion=Oxidation.
So we have the equation: (fuel) + O2 = By products...often H2O vapor in the case of Hydrogen containing substances (Most fuels) and CO2 in Carbon containing substances (Largely the class A type fires)
In the case of Hydrogen combustion we get:
2x H2+O2 = 2x H2O (Technically 2x H2+O2 <=> 2x H2O)
So we see that the rapid, complete oxidation of Hydrogen (catalyzed and driven by heat) results in the formation of water. Water is essentially a "by product" of the combustion (rapid, exothermic oxidation) of Hydrogen. Because Hydrogen is now already oxidized, it is no longer available to its environment, neither is the Oxygen that oxidized it. Of course the reaction will run in reverse, given the right conditions. But simply the heat and chemical chain reactions caused by, say a structure fire, are just not enough to drive the equation to the left.