Do solids burn

Discussion in 'Chemistry' started by Asguard, Mar 24, 2008.

  1. Fraggle Rocker Staff Member

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    Antoine-Laurent de Lavoisier. Pronounced la-vwa-ZYAY. I looked it up to make sure I was right. You never can tell with French, there might have been an apostrophe after the L.
    It's the carbon dioxide level in your blood that triggers the "out of breath" feeling. (And don't ask me how that happens.

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    ) This is why carbon monoxide is deadly. It takes up the spaces on your blood cells that would normally go to carbon dioxide, yet it doesn't trigger the out-of-breath feeling, so you just lose consciousness without realizing that you need to breathe. This will happen even if you're removed from the space with the carbon monoxide in the air and the carbon dioxide level in your lungs returns to normal.

    This is also the mode of asphyxiation at high altitude without a pressurized environment. There is so little oxygen in the rarefied air, that your respiration does not produce enough carbon dioxide to make your blood "feel" out of breath. You have to force yourself to breathe consciously, and sooner or later you'll forget.
     
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  3. Norsefire Salam Shalom Salom Registered Senior Member

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    True, but it also changes the entire chemical composition; it's a chemical change, not just a physical change.
     
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  5. Pronatalist Registered Senior Member

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    Almost always I think. It's good often that it's the gas that's burning, and not the solid directly, although the heat of the fire can change more of the solid into gas. When solids burn, the result does tend to be rather "explosive." The reactants are jammed too close together, so the fire spread cascade is too rapid. But then that can be useful, for some of the better uses of explosives.

    Likewise, probably gravity helps make fires more managable. Can you imagine perhaps how much more violently forest fires would burn, without gravity to carry most of the heat upwards, often actually away from the fire? (Consider how natural forest fires tend to travel faster uphill.) Zero gravity fires are likely far more dangerous, as they may simutaneously grow in all directions at once? And far more quickly overheat spreading their spread, as the heat just sits right there and radiates all around?

    Since gases more readily burn, than solids, one factor being the greater ability of solids to wick the heat away to keep the temperature below that of combustion, isn't that largely what "regulates" the burn rate of candles and karosene heaters? As long as the fuel liquid isn't too reactive, say like karosene rather than gasoline, it tends to be reluctant to burn without a wick to draw it up into increased exposure to the air. And the fuel helps shield the wick from burning itself, the fuel being more reactive. Isn't that how candle wicks tend to naturally regulate their length?

    Why can you burn some steel wool, but not a hunk of steel? Steel wool has more surface area, while a more solid hunk, wicks the heat away too fast to ignite. Even wood does this to some extent. It's easier to ignite small pieces, shavings, or paper, than a big log. But once the big log is heated by smaller kindling and gets hot enough, it will burn too, but often burn poorly, the inside still too much shielded from the oxygen.
     
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  7. Pronatalist Registered Senior Member

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    So it's not the carbon monoxide itself that is dangerous, but the low oxygen levels it causes?

    I hear the carbon monoxide bonds better to the hemoglobin in the blood, than the oxygen does. That displaces the oxygen it was supposed to carry. At low levels, there shouldn't be much affect? Of course like lots of chemical mixtures, CO will disipate when removed from the environment causing the problem. But "going outside" may not solve this condition fast enough. Therefore, the treatment is to administer oxygen to the patient, for a while, until the CO can disipate from their blood.

    Why is it that low atmospheric pressure causes dangerous lung fluid accumulation in mountain climbers sometimes? And are such conditions less likely with practice and experience? Does the body soon adapt naturally?
     
  8. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I know a lot but learn from more than half your posts. Thanks.
     
  9. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I do not know why (Or even about that fact.) but, there is an interesting an important interaction between CO2 concentration in the blood and blood capillaries in the brain, and I think only there, but am not sure of that. The brain consumes a very disproportionate part by weight of you blood oxygen and corresponding makes more CO2 per unit mass than any other tissue in the body, except the retina. Different parts of the brain process different information, do different jobs at different times more intensely than at other times. The capillaries expand significantly as CO2 builds up. This makes less hydrodynamic resistance to the blood flow locally. This is how some brain activity measurement techniques are possible - the areas with increased activity have more blood in and flowing thru them.
     
  10. Asguard Kiss my dark side Valued Senior Member

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    Umm no, that would be the case with CO2 or nitrogen or any other non toxic gas but with CO the problem is as you said that it "out compeats" the O2 molicules on the hemoglobin so it suffercates you from the inside (rather than from no air in the lungs).

    I was going to respond to FR but i need to check my A&P book to make sure i have the breathing responce correct. I THINK it has to do with the acidising of the blood caused by CO2 but im not sure (it could be a direct responce to the CO2). I DO know that he is right that the breathing responce is caused by CO2 build up rather than a lack of O2 which is why if you go to long in an O2 poor enviroment breathing in say helium then you wont just automatically start to breath again, you need outside intervention to get the O2 in so the CO2 can build up again to alow you to breath
     
  11. weiguxp Wikichem.net - WikiChem Registered Senior Member

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    since the iron wool example has been cited, i'd like to say that things to get things to burn, you need to find a way to get oxygen to the site of action. thats why flammable liquids burn by producing vapour (so its easier to feed oxygen to the site)

    so i'd say if get the solid in a dust form (more surface area) you can burn solids.

    this is shown by the aluminium example
     
  12. Engulfed_Door Registered Member

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    answer: Wood is a solid is it not? So is paper. Magnesium burns to so does coal.
     
  13. temur man of no words Registered Senior Member

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    Sure, all the time.
     
  14. Pronatalist Registered Senior Member

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    But don't some of those substances you mentioned, put out flammable gases, when heated to combustion-near temperatures? So is the material burning as a "solid," as a "gas," or some combination of both?

    You mention wood and paper. Do you know what "flashover" is? That's when a room on fire, accumulates so much incomplete combustion flammable gases (from paper, wood, and furniture stuffing/foam) near the hot ceiling, and then the heat builds up, and a huge fire "flashes" along the ceiling. (Is that what often breaks out the windows in a fire?) Sometimes it's triggered by opening a door, and admitting fresh oxygen to the fire. That's why they say in a fire, before opening a door, you check it to see if that door is hot. The character in the movie "The Towering Inferno" didn't think to be careful of that, and so got burned when he opend the door to check out the smoke coming out around the door. Actually, they took precautions to protect the actor. I think in the commentary/behind-the-scenes, they make some mention of him wearing some sort of mask, perhaps visible by slow-mo-ing or freeze framing the DVD. They may also have some sort of gels that they can coat the skin with, to protect actors from the heat?
     
  15. Roman Banned Banned

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    Solids burn, rust being the most obvious example. Coals also burn, as do big thick logs. That is, they're a solid when the oxygen oxidizes it, but soon become gaseous products.

    As for flashover, I'd guess that it's simply an accumulation of flammable hydrocarbons not necessary for a fire.
     
  16. Pronatalist Registered Senior Member

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    Gases burn more readily than solids, but solids can burn also.

    Fires sometimes get so hot, that they emit clouds of flamable gases faster than the fire can suck in the needed oxygen, and so as the cloud grows and finds oxygen, it can explode into a huge fireball, spreading even more heat speeding the spread of the fire.

    Natural forest fires apparently can experience "flashovers" of a sort too.

    Mother Nature's Secret Weapon
    http://blog.wired.com/defense/2007/09/mother-natures-.html
     
  17. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    Paper?
     
  18. Pronatalist Registered Senior Member

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    I think paper emits gases, and the gases burn.
     
  19. Clown Banned Banned

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    Do solids flow?
     
  20. Enmos Staff Member

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    Glaciers, continents..

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    They don't burn as far as I know though.. lol
     
  21. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Sure, but slowly. I have seen some beautiful examples in rocks with the originally horizontal strata now in almost a "hair-pin" curve. For more rapid example, visit any metal stamping plant or look at an alumimum coke can after you empty it and step on it. (I am not sure how it is made -probably that to is "solid metal flow" under pressure but perhaps the metal is hot when drawn into can shape to thremally relieve the stresses as it is made.)
     
  22. Asguard Kiss my dark side Valued Senior Member

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    what about the himolayers
     
  23. Enmos Staff Member

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    Continents crashing into each other.
     

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