Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: taregg on 18/10/2011 21:56:39
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is it true that boron more flammable than carbon ....boron ex sample ....580c and carbon454c(autoignition temperature)
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Fundamentally, flammability is a simple switch concept. If something can be induced to undergo a self-sustaining reaction with oxygen in air in ambient conditions it is flammable; otherwise, it is not.
If we want to create a scale of "flammability", so that things can be said to be "more flammable" or "less flammable", then there would be several different ways of going about it: auto-ignition temperature, flash point, exothermicity (how much heat per gram or per mole the reaction gives out). rate of reaction with oxygen, minimum partial pressure of oxygen that can sustain the reaction, etc.
The different scales do not all produce the same order of "flammability".
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so boron is it more flammable than carbon ?
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Is Andy Murray a better athlete than Paul Collingwood? If you measure by the "tennis" scale, then yes, but if you measure by the "cricket" scale, then no! The question you ask about flammability is very much like that.
You provide figures for auto-ignition temperature which show a higher temperature for boron than carbon, so on the "auto-ignition" scale carbon is the more flammable if your figures are right. However the figures that I find, from more than one source, puts the auto-ignition temperature of carbon at 700°C, which would make boron the more flammable material on this scale. The 454°C auto-ignition temperature appears to be that of butane, and a misprint as far as carbon is concerned.
It is not easy to find a flash point for either material. In terms of exothermicity, boron also comes in ahead of carbon, generating about 50% more heat energy per gram (or 40% more per mole) in its combustion reaction. For other possible scales of "flammability" it is not easy to find data. I think it is a fair bet overall to say that boron is more flammable than carbon.