Dumb question about fire sorry

Discussion in 'Chemistry' started by BarbieGirl14, Mar 30, 2008.

  1. BarbieGirl14 Registered Senior Member

    OK. So. I'm almost sure everyone has a little pyromaniacness in them lol. Not talking about the psycho peeps, but the normal people who have a curiosity about what kind of magic is it, that turns stuff into ash.

    Before I ask this question, I'll tell you what I know that i think is priority to this question so you dont have to baby me. I'm trying to find a complete understanding of fire. Down to what happens at a molecular, elemental, and atomic level.

    I know about the elements, chemistry, and nuclear fusion. I know the make up of an atom, and the electron shells and covelance shell and all that how it works. I understand most about how direct currents work and how magnetism works. BASICLY. pls dont think i know all this.

    My question is: What makes fire work? What makes it hot? Why does an element just like destroy itself? How can fire make a stable element burn when spread? Why does some stuff burn easier then others?

    Please explain to me everything about how fire works.... I really need to know because its such a basic thing... I feel completely dumb not understanding it...

    ty for reading =D
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  3. Repo Man Valued Senior Member

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  5. BarbieGirl14 Registered Senior Member

    It doesn't explain fire.

    It says a bunch of huge words I'v never heard of, and then it puts them together.

    Then they throw together a bunch of equations which confuse me more because i cant relate them to the big words.

    Its like.... When you look up a word in the dictionary, and it gives you an acronym for an answer. Then you have to look up the acronym and pray it doesnt send you back to where you started.

    Now do that with 200 huge words from wiki. A site where it assumes I can speak english like a university teacher with a doctorate in english.

    Thank you tho for trying lol. Its the thought that counts =P
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  7. cosmictraveler Be kind to yourself always. Valued Senior Member

    Fire is of many types. Some are chemical others are solids and some are atomic. Which type are you refering to?
  8. Fraggle Rocker Staff Member

    That's a common problem. People assume that because something is part of everyday life, it must be simple enough to understand with just a patient explanation. The universe isn't like that. Some things are really complicated. You might actually have to read a freshman chemistry book and a freshman physics book to understand fire. There might be too much knowledge required for the understanding, to be able to cram it into a fifteen-minute read.

    Now that I've posed that challenge to our chemists, let's see if they rise to it.

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    Personally I think you'd have better luck with this question on the Physics board. It's just as much a physics question as a chemistry question, perhaps more so.
    I think you mean synonym, not acronym. An acronym is the first letter or first couple of letters from each word in a phrase, crammed together to form a new word. Like laser = Light Amplification by Stimulated Emission of Radiation. That's an acronym. Or Cobol = COmmon Business Oriented Language.

    There's your lesson today from the Linguistics Moderator.

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    I have to admit that I don't think the Wiki article on "Combustion" is very useful. The one on "Fire" is a little less intimidating, although for the goddess's sake I hope people have enough initiative to look up the word they want on Wiki before coming here!

    Or, here's a website called "How Things Work" that is at the level you're looking for. I don't know if this will satisfy you because I'm not sure what kind of understanding you're looking for. As others have said, fire almost requires you to understand plasma, which is a fourth state of matter (besides solid, liquid and gas) that they didn't teach when I was in high school. Once a phenomenon transcends our intuition, the concept of "understanding" gets pretty complicated. Anyway, see what you think of this one.
  9. BarbieGirl14 Registered Senior Member

    I do understand plasma, and if it's as simple as atoms losing all there electrons then im happy.

    My problem is this.

    Ash... im pretty sure its made up of carbon... carbon has electrons.... why did these electrons survive...

    Also doesnt that mean solids and liquids would have to turn to gass before they plasmize or w.e its called...

    Also... an atom with no electrons are umm positive charged... does that mean they would fly away from each other and steel electrons from another atom to form a new element???
  10. kevinalm Registered Senior Member

    Ash isn't carbon, although there may be some carbon in ash. Wood and paper contain quite a few metal compounds, Na and K salts for example, that are converted to oxides and carbonates in the heat of burning. Metal oxides and carbonates tend to have very high melting and boiling points, and condense out almost as soon as they are formed, so they aren't carried away by the flame and remain behind as ash.
  11. Roman Banned Banned

    Yeah, it is pretty magical stuff. I practically have a chem minor, and I still have a difficult time convincing myself I know what it is.

    The fire we're familiar with hasn't anything to do with nuclear fusion. Fusion involves subatomic particles; fire is just valence electrons changing orbitals.

    Alright, you're messing up some terminology.

    Fire doesn't destroy anything in a real sense of the word: no matter is lost cause matter is neither created or destroyed. At least, until Einstein came along. With fire, the elements just change combinations and states, where an element is one of those 92 (or 106 or whatever) substances on the periodic table. An element cannot be broken down to any more basic compound or changed to another without enormous amounts of energy- essentially until the protons and neutrons start flying off it (or getting added to it).

    Fire is also called combustion or oxidation. Oxygen, the element (it exists down here at atmospheric level as O2, or two atoms of oxygen bonded to each other), is extremely electronegative- it wants electrons. The carbon and hydrogen atoms that make up wood (or more correctly, cellulose, a type of sugar) have bonds that oxygen is able to break and snatch up electrons. Carbon has four valence electrons, but it holds electrons only weakly in its valence shell (valence shell being the outer electrons of an atom available for bonding). Oxygen is able to break these bonds, by pulling the electrons to itself.

    So here you have this oxygen coming in and reassemling everything, picking up two hydrogen atoms to fill its valence shell, becoming H2O (water) or two oxygens filling their valence shells by attaching to carbon becoming carbon dioxide (CO2).

    The heat and light is due to the energy in the bonds breaking and being released. Energy can take various forms- one is kinetic energy, which, on the atomic level, is heat, since you've got a bunch of tiny molecules vibrating furiously. Another form of energy is electromagnetic, in this case, visible light and infrared radiation. If you ask the physicists, they'll probably tell you that all energy's the same, but for everyday purposes, energy comes in different types (chemical, kinetic, potential, etc).

    Now why does fire work the way it does? Basically, it's a somewhat slow chemical reaction that catalyzes cellulose into water and carbon dioxide by oxidation. A slower form of oxidation is when iron rusts. Rust is metal burning very slowly (unless it's a thermite reaction, then you can burn through a fucking engine block). Extremely rapid burning would be in the case of a gasoline explosion.

    Other electronegative elements, such as the halogens (iodine, fluorine, bromine, etc), can, in gaseous form, react explosively with other compounds. However, due to the extreme toxicity and relative rarity of halogens, not to mention the impracticality of creating gigantic explosions with toxic gases to yield more toxic compounds, means we have relatively little familiarity with these sorts of combustion reactions.

    Another way to view fire is as photosynthesis backwards. The heat and light you see is energy that's been stored by the sun by the plant, and is now being released. When those bonds are broken by oxygen, photosynthesis runs backwards, to yield CO2 and H2O, while releasing the energy in the bonds that was required to form the cellulose.
  12. BarbieGirl14 Registered Senior Member

    Ok wow thats totally facinating lol.

    So just to clarify.

    The elements that burn at a very high tempature turn into ash because they go solid, liquid, gas, plasma, gas, liquid, solid in like super super speeds?

    Also, do bombs based off uranium explode because they have so many electrons, that when it loses them they fly out everywhere making like... a big big fire???

    Also does an atom bomb really split an atom, or is it something similar to fire also?

    Also isnt wood carbon? doesnt it take like 1400 degrees to burn carbon.... I doubt a little fire can burn at 1400 degrees...

    Does this mean all fire is plasma?

    does plasma destabilize everything it touches?

    Why would fire need oxegen to burn, when its fuel source is saposedly the release of electrons from w.e its burning?

    why does fire produce carbon dioxide when it burns stuff? does that mean the solid went to liquid, then gas, then plasma, back to gass, mixed with oxegen in the air, and became CO2?

    can an element be unstable and NOT combust?

    does that mean everything an electron jumps to another atom, its plasma wile its jumping?

    is lightning plasma?
  13. BarbieGirl14 Registered Senior Member

    ok why does wood like sit there happily.... then you have to give it fire to make it go unstable and give electrons to the air.... is this because it needs the heat to give more energy to the electrons in the covelant shell so they move faster and fly out of orbit easier?

    omg i think im getting it im so excited lol
  14. Roman Banned Banned

    These are different things.
    For your standard lets make a fire, daddy, ash are the metals and salts that were locked up in the wood that don't burn off- they're left as a solid, powdery residue. Most of the wood "disappears" because it becomes, mostly, two gases- water vapor and carbon dioxide (you know, the shit Al Gore is freaking out about).

    The wood isn't melting- pieces of it are being torn off by tiny, hungry oxygen atoms and caring it away. And speeds are relative. Wood burns slower than, say, a propane tank exploding. Wood burns much faster than iron rusting. Different burning rates are useful for different things. A slow, steady burn is good for heating and cooking with. Rapid explosions, like gasoline, are good for powering motors. A car engine runs by many rapid explosions forcing the pistons to turn a crank that makes the wheels turn. That occurs because the oxygen iz in ur bonds, stealin ur electrons, very quickly. That means a great deal of energy is released all at once.

    As for melting and boiling, these things are due to something else entirely. On the atomic scale, everything exists due to probability. When you get up to our scale, the macroscale, laws of averages take over. Hammers aren't quantum tunneling through walls to clawhammer you in the back, for instance.

    For atomic particles, they're held together by attractions due to charges. At any point, there's a chance that an atom won't be attracted to another, and it will float away. So that bar of iron? Every now and then, a little atom of it floats off. This is called sublimation; a solid turning into a gas.

    As you heat a substance up, the atoms begin vibrating, weakening the attraction the particles have for each other, increasing the chance that they will leave each other.

    Some liquids have very low vaporization points, liquid nitrogen for instance, boils even though it's extremely cold. This is because atmospheric nitrogen, N2, is a very neutral gas, and isn't really attracted to other molecules. The slightest vibrations (heat) interrupt the intermolecular forces that keep it as a liquid.

    Atomic bombs explode due to a nuclear reaction, not a chemical one. Chemical reactions are due to electrons changing places in bond relationships. Nuclear reactions are due to protons and neutrons changing places. There is a tremendous amount of energy released by an atomic bomb, which causes everything around it to burn.

    All compounds have an activation energy to begin turning into another compound. The activation energy of making a leaf is quite high- you need to shine sunlight on a plant all day, every day, for many days. The activation energy to convert that leaf back into the sunlight, oxygen, and water that makes it up is relatively low- simply a burning match or even sunlight focused on it for a few seconds.

    Due to the immense heat from an atomic bomb, many activation energies can be over come, leading to things that normally wouldn't burn, burning. It also will create enough heat to simply vaporize things- melting stuff off. The force of the explosion will also shred many soft substances, collapsing concrete buildings and blowing them apart.

    Quite different, as outlined above. An atomic bomb splits an atom, breaking the atomic nucleii and releasing a tremendous amount of energy. A fusion, or hydrogen bomb, fuses atomic nucleii, creating new elements, and in doing so, releasing a lot of energy. Stars, and our sun, work on the same principle, adding hydrogen to other elements to make heavier ones. A hydrogen bomb combines two hydrogens to make a helium. Our star will be making iron in billions of years (at which point, its stellar arteries will clog and choke it to death). Maybe it's iron. Our star may only be hot enough to get up to carbon or silicon or something.

    Wood is mostly units of C6H10O5 linked together. The heat from the reaction is due to the hydrogen atoms leaving carbon and hooking up with oxygen; and the oxygens also hooking up with the carbon. So you're not burning pure carbon- you're breaking bonds and reforming them between several elements.

    No. Plasma is an ionized gas, where the electrons are not associated with (orbiting) the nucleus.

    Depends on how much of it there is, and what it touches. The sun is plasma, for instance, and if it touches you, you're toast. Well, superheated plasma.

    But if you break open one of those plasma ball thingies, you may get a nasty shock, but there's too much space- the gas will spread out, the electrons will be picked up atoms, and there won't be enough energy in the system to keep the electrons disassociated.

    There are also cold plasmas and stuff, but... that's not really fire. At least as we're familiar with it. It's similar in that there are transitory electrons and electromagnetic energy being released on the visible spectrum, but that's it.

    Not all fires use oxygen to burn. However, it's still a chemical reaction. The bonds would never be broken and released without the proper reagent. In the case of your fireplace or BBQ grill, oxygen is the reagent. It's like mixing baking soda and vinegar- if baking soda makes vinegar foam, why would you even need baking soda?

    Not necessarily. In the case of wood, the oxygen is just pulling pieces of it off, going straight to gas phase. The carbon dioxide is created because oxygen is hungry for electrons (it wants two of them) and carbon has four of them to give away. If you do the math, you'll see that the best combination is 2 oxygens and one carbon.

    Absolutely. Stability is a relative term. If activation energy isn't met, then it won't combust. If you don't get that wood hot enough, it will never burn. Note, however, that the wood is not an element, it's a combination of elements. There are many elements that are "unstable", but won't do anything if conditions aren't right. Pure potassium, for instance, is a soft, grey metal. If exposed to water, it will violently explode. Like, blow up a dish tank explode. Hopefully they're still doing the alkali metal demonstrations in highshcool chem.

    Not in the precise sense, no. A plasma is a state in which electrons become dissociated and are free. In most chemical reactions, valence electrons are only free for a matter of picoseconds. That's 0.000000000001 seconds. It's pretty quick.

    No, though it probably briefly creates plasma on its way down. Plasma is a cloud of gas where the electrons are no longer hanging out with the nuclei of the atoms. Lightning is a flow of electrons that move through matter.
  15. BarbieGirl14 Registered Senior Member

    wow thanks so much! I almost feel like I could teach dad lol. he will be really happy. Now when I look at our fire place, I can point out exactly what is happening =D

    ty so much lol
  16. Roman Banned Banned

    Yeah, but when he asks you where you learned that, what will you tell him?
    He'll soon be giving you lessons on what counts as a reliable source.
  17. BarbieGirl14 Registered Senior Member

    I hope not lol

    Ok so... the orangeish blueish greenish redish stuff in a fire place..... is plasma? sorry sorry i hav to ask its like the fire
  18. Roman Banned Banned

    The light is due to bonds breaking and releasing energy. This energy excites photons that vibrate at certain wavelengths. We see these wavelengths as colors.

    No plasma involved.

    This is what plasma looks like.
  19. BarbieGirl14 Registered Senior Member

    so in a light bulb... electrons make photons move and make light....

    wow its so late... i have school tommorow im going to like die lol

    shudnt of slept untlll 12 today =(
  20. Roman Banned Banned

    In some lightbulbs, yes, you are looking at a plasma. Incandescent bulbs are due to a metal filament, typically tungsten, having electricity run through it. This makes the wire very hot and it emits light. The fluorescent lights are full of a gas (usually a mercurial compound) that have electricity run through them, creating a plasma. I think.

    The type of light that comes out is due to the sort of compound that has electricity passed through it.
  21. BarbieGirl14 Registered Senior Member

    ok ty soooo much good night

    it was really nice for someone so smart to waste ther time teaching a 8th grader about fire but im really happy cuz i know it now lol

    ty so much lol

    ok night lol
  22. cosmictraveler Be kind to yourself always. Valued Senior Member

    If you are an 8th grader I'm Yoda!

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  23. BarbieGirl14 Registered Senior Member

    Lol, omg how impolite.

    Are you implying i'm dumb? =P

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