• flambonkscious@sh.itjust.works
      link
      fedilink
      English
      arrow-up
      9
      ·
      1 year ago

      Really? I remember asking someone why the two happily ignite, but together never do, and their explanation was that the molecular bond is too strong it keeps them stable?

      I was a teenager at the time though, so just accepted it - is this really accurate?

      • AngryCommieKender@lemmy.world
        link
        fedilink
        arrow-up
        40
        ·
        edit-2
        1 year ago

        It’s absolutely accurate, you’re just missing the fact that H2 and O2 have to oxidize, aka “burn,” to create that bond. Literally the easiest way to “create” water is to take a flask of pure hydrogen, a flask of pure oxygen that contains roughly 2.5 times the hydrogen vs oxygen to account for inefficiencies, “pour” those flasks into a container, and light it on fire. The ensuing explosion will convert almost all the hydrogen and most of the oxygen into water. Please stand well back, like behind a reinforced bunker wall if you attempt this.

        Forming that bond frees up a single Oxygen atom, splitting the bond it has with its partner and causing a reaction that ends up releasing the excess energy of the Oxygen molecule, and bonding one of the Oxygen atoms to two Hydrogen atoms, the extra Oxygen atom then allows the oxidation process to happen. It also releases a large amount of energy, if you’re a Hydrogen or Oxygen atom, or a tiny amount of mostly heat energy if you’re a human. (Problem if you’re a human is that you aren’t capable of causing a single H2+O2+e→O1+H2O+e^x, so you’re gonna get a large explosion for even small amounts of a mixture)

        This is also true of all other “ash” products created by oxidization of pretty much any fuel from trees to iron. Once you “burn” the compound, it becomes chemically inert for further oxidation, because the atomic bonds of the molecules are about as stable as they can get.

        This is why, chemically and physicsally speaking, burning or Oxidizing fuel creates plasma that we call fire. That plasma is the excess energy being expelled as the fuel combines with mostly Oxygen, to form ashes.

        Water just happens to be the only type of ash we are familiar with that isn’t dry, and instead gets things wet. There may be a few others, but I suspect that most of them are acids or bases that we don’t regularly have any contact with.

        Edit: source: former US Navy Nuclear Power Program Electronics Technician Instructor. I understand the physics involved, and can easily do the math that the chemistry uses. I don’t know shit about biology, so there are probably some biological protein chains that negate literally everything I just said.

        Edit 2: Sorry for the first 20 minutes, my comment was reversed with O2 and H2. I literally had to type out the math to remind myself how that reaction works.

      • Acters@lemmy.world
        link
        fedilink
        arrow-up
        4
        ·
        1 year ago

        As others said, hydrogen and oxygen gas in the same container will not create water until energy is put in. Fill a Ballon with a balloon with a 2:1 molar ratio of H2 and O2, then pop the Ballon with a flame, and you will get a cloud of water vapor. Without the fire, popping the balloons with a needle will only release the gases.

  • ThatWeirdGuy1001@lemmy.world
    link
    fedilink
    arrow-up
    19
    ·
    1 year ago

    So I know this is just a meme but it’s oxygen really the only reason fire can exist? Like don’t other things burn on their own with no oxygen present?

    • CarbonIceDragon
      link
      fedilink
      arrow-up
      25
      ·
      1 year ago

      There are other chemical reactions that produce heat, but fire is specifically a rapid oxidation. There are other oxidizers though that can result in an oxidation type reaction though, a few are even better than oxygen at it even, like fluorine (which is why pure fluorine is such dangerous stuff)

      • KuraiWolfGaming
        link
        fedilink
        arrow-up
        7
        ·
        1 year ago

        Chlorine Trifluoride is a better oxidizer than Oxygen itself. Hell, the germans in WW2 tried making self igniting flamethrowers with the stuff. But stopped because it was too nasty to work with.

        At that point, they might as well just spray it directly on people. Screw using a fuel to ignite when the trifluoride is enough to set fire to literally anything. Even wet sand can be burnt by it.

        • snugglesthefalse@sh.itjust.works
          link
          fedilink
          arrow-up
          8
          ·
          1 year ago

          Which reminds me of this quote "It is, of course, extremely toxic, but that’s the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water-with which it reacts explosively. It can be kept in some of the ordinary structural metals-steel, copper, aluminium, etc.-because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminium keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes. "

          • KuraiWolfGaming
            link
            fedilink
            arrow-up
            2
            ·
            1 year ago

            Yes, from the book Ignition! by John Clark. Also quoted by Derek Lowe in an entry of his “Things I Won’t Work With” articles.

    • chemical_cutthroat@lemmy.world
      link
      fedilink
      arrow-up
      16
      arrow-down
      2
      ·
      1 year ago

      There can be a release of energy without oxygen, but it will not result in a fire, just an explosion. You can make arguments for things like the sun “burning” in the vacuum of space, but that is fusion, and a far different thing than lighting a match.

    • TheChurn@kbin.social
      link
      fedilink
      arrow-up
      12
      ·
      1 year ago

      There are plenty of things that can cause fires that are not oxygen, and don’t contain oxygen.

      The halogens, Fluorine and Chlorine in particular, are powerful oxidizing agents on their own and can produce flames in the same manner as common flames.

      Here’s a report on the spectra of flames produced by combustion in a Fluorine atmosphere (PDF warning).

    • Donjuanme@lemmy.world
      link
      fedilink
      arrow-up
      9
      ·
      1 year ago

      Some metals (the ones that require super special fire extinguishers) can keep an exothermic reaction going (magnesium I believe, and sodium I’m pretty sure) but rapid oxidation (rusting) is the most common method of combustion.

      Oxygen is so combustible that it’s toxic to life, and would have killed life as it was a billion years ago (number from my ass) which produced oxygen as a byproduct of photosynthesis if it weren’t for the development of mitochondria.

      A few other things (elements) can burn without oxygen, but not many, and they normally need a pretty large activation temperature.

      • ThatWeirdGuy1001@lemmy.world
        link
        fedilink
        arrow-up
        5
        ·
        1 year ago

        So is it just the definition of “fire” itself? Like only something burning with oxygen is “fire” but if it’s another fuel source it’s not technically “fire” but we call it fire anyway?

        • Donjuanme@lemmy.world
          link
          fedilink
          arrow-up
          9
          ·
          1 year ago

          Burning with oxygen is oxidation, things oxidize when the element oxygen binds with another element, which it’s very prone to doing. Oxidation with iron is rust, it just happens much more slowly (but still exothermically) than when biological compound oxidize they release energy more rapidly, rapidly enough to cause other nearby organic bonds to break and expose themselves to sites for more oxidation to take place.

          There can be electrical fires, chemical fires, classic fires, and self fueling fires (the kind you were originally asking about). There are probably more categories now. Always be sure to use the proper fire extinguisher for the fire at hand.

  • MonkderZweite@feddit.ch
    link
    fedilink
    arrow-up
    6
    ·
    edit-2
    1 year ago

    I mean there is some stuff that makes water flammabe. What was it again? Pretty nasty stuff, that explodes if it touches anything. It’s an acid i think?

  • I_am_10_squirrels@beehaw.org
    link
    fedilink
    arrow-up
    2
    ·
    1 year ago

    Combustible compounds react with oxygen to form lower energy oxidized compounds. Carbon is oxidized to carbon dioxide. A fully oxidized compound can’t be further oxidized under normal conditions.

    Water is the most oxidized form of hydrogen. It can’t be further oxidized under normal conditions, hence why it’s not combustible.

    Methane is the most reduced for of carbon, so it really wants to be oxidized. Carbon monoxide is only partially oxidized, so it’s still flammable.