okay well then what about spontanious combustion? how does that happen?
444820
Spontaneous combustion, or roughly, any spontaneous reaction would occur if the reactants are;\n1) thermodynamically unstable\n2) kinetically unstable\n\n1) Thermodynamic stability:\nAll combustion reactions are exothermic. If you draw the energy profile for a combustion reaction, the reactants are at a higher energy state and the products are at a lower energy state, since heat energy is released. Thermodynamic stability has to do with the relative energy of the reactants or products. As stated above, the reactants are at a higher energy state and they tend to release energy when reacting, so the reactants are said to be thermodynamically unstable. This unstability would result in a spontaneous reaction.\n\n2) Kinetic stability:\nThis takes into account the activation energy of the reaction. According to the 'Collision Theory', reacting molecules must have sufficient kinetic energy while colliding in order to overcome the activation energy for the proceeding reaction. Considering the thermodynamically unstable reactants above, if the reacting molecules can collide with each other with enough internal energy that is greater than or equal to the activation energy, they would be able to reach the transition state and form products spontaneously, and hence be termed kinetically unstable. \n\nIt happens, however, that in some combustion reactions, the reactants are thermodynamically unstable and you expect them to react just like that, but they don't because they're kinetically stable (internal energy not enough to overcome activation energy), and so they need to be given more internal energy in the form of a spark, ignition, presence of light etc., in order for the reaction to proceed.
641178
"Fire is the rapid combination of oxygen with fuel in the presence of heat, typically characterized by flame, a body of incandescent gas that contains and sustains the reaction and emits light and heat." \n\nLet's go through this bit by bit:\n\n(1) Rapid combination of oxygen with fuel in the presence of heat. Oxygen, fuel, and heat are the essential ingredients of fire.\n\n(2) Typically characterized by flame. The pup qualifier "typically" allows me to sidestep the issue of apparently nonflaming fires, like you get with burning charcoal. I suspect charcoal fires do create flame--you just can't see it due to the lack of impurities or incompletely burned fuel in the plume. (You can't see a fuel fire at an Indy or CART race either, because the cars run on clean-burning methanol.) But that's a matter we can leave for another day.\n\n(3) Body of incandescent gas. Flame defined. Most encyclopedia and dictionary definitions blow past this entirely, allowing persons such as yourself to imagine that fire is "pure energy" or similar nonsense. We say "body" because the gas has a characteristic structure and composition. We say "incandescent" because (a) it sounds scientific, (b) it means "luminous with intense heat," precisely what we are attempting to convey, and (c) if the Teeming Millions are going to learn one vocabulary word today, by God "incandescent" should be it.\n\n(4) Contains and sustains the reaction. Flame isn't just the result of fire; it is the fire. What's more, without the flame's heat the fire would go out.\n\n(5) Emits light and heat. Duh. However, we mustn't overlook the obvious.
1184525
Depends on what is being split and where the combustion takes place.  The combustion alone will produce changes of oxygen, hydrogen and any other chemical in the air or around the combustion.  The remaining products will more than like be water, carbon min-oxide, etc.
283306
It is supposed to be a mysterious, sudden ignition that almost magically destroys all or most of a human body without damaging nearby items.\n\nHowever, it has been well documented that this phenomenon can happen under some pretty common conditions.\n\nTake a roughly humanish mammal, and rig it up so they don't move and/or do not react to the pain in time. Drunkeness or drugs usually does it for humans. Illness or even death by other causes will suffice as well.\n\nMake sure the body is wrapped in or sitting on a flammable material that can absorb the greases released during the process, then act as a wicking material to keep the fires going at relatively low levels.\n\nIgnite the fabric (many cases of SHC involve smokers). As the fabric and body start to burn, the relatively low-temp heat will release body fat (most victims of SHC are also overweight), which goes into the fabic, often a chair, and continues to feed the flame.\n\nThe key factors here are: lots of time- it will take a while to do this (most cases of SHC had plenty of time to work); and the wicking effect to ensure that the fire never goes out. it needs to keep going until the fats and other flammables are consumed.\n\nInterestingly, the low temps of the fire limit the damage caused outside the area soaked in fats- one of the big mysteries in SHC. Not even much smoke is produced!\n\nThis was shown on CSI, and on some investigative reports as well, using pigs. The factors needed for the experiments to work are present in almost every case of SHC.
899050
It does NOT occur spontaneously.  If it did, you wouldn't need a pilot light in your gas stove of heater!  Combustion takes place by the mechanism of free radicals.  And CH4 won't form any at room temperature.  Once some free radicals are created (by high temp.) the reaction is self-sustaining.\n\nComment on the mention of Pt below:  Yes they DO still do that; but they use either Pt mesh or wire.  That's the way pilotless gas burners work.
570402
Nothing...unless you light a match, then...BOOM!  In the case of Oxygen and Hydrogen, you'll get pure water afterwards...that should put out the fire you just started :)\n(Not really)
758386
Assuming there is oxygen present, in any direction. Most likely the direction which presents the input of oxygen i believe. Some great pictures on the NASA website linked below. There have been some controlled experiments for combustion done on Space Shuttles.
626673
I think the water is the end result of a chemical reaction. Water is not combustible, and never will be. It is a life giving force, unlike fire. I found out that bleach and this other cleaning liquid turn into nerve gas when mixed together. I don't have a good explaination for why this happens. It just does.
832651
A candle flame is often used to illustrate the complicated physio-chemical processes of combustion. The flame surface itself represents the location where fuel vapor and oxygen mix at high temperature and with the release of heat. Heat from the flame melts the wax at the base of the exposed wick. The liquid wax rises by capillary action up the wick, bringing it into closer proximity to the hot flame. This close proximity causes the liquid wax to vaporize. The wax vapors then migrate toward the flame surface, breaking down into smaller hydrocarbons enroute. Oxygen from the surrounding atmosphere also migrates toward the flame surface by diffusion and convection. The survival and location of the flame surface is determined by the balance of these processes. \n\nIn normal gravity, buoyancy-driven convection develops due to the hot, less dense combustion products. This action has several effects: (a) the hot reaction products are carried away due to their buoyancy, and fresh oxygen is carried toward the flame zone; (b) solid particles of soot form in the region between the flame and the wick and are convected upward, where they burn off, yielding the bright yellow tip of the flame; (c) to overcome the loss of heat due to buoyancy, the flame anchors itself close to the wick; (d) the combination of these effects causes the flame to be shaped like a teardrop.
771844
A\n\nVolcanic explosions such as St. Helen's are cause by super heat gases.  Often Steam.
721969
Water is what you get when you burn hydrogen. After combustion the bonds between the H and O atoms are so strong, that no more burning happens.\n\nWhen you burn any molecule that contains hydrogen, like CH_4,\nnatural gas, the same thing happens. All the hydrogen ends up in water molecules.
661131
Oh boy.  There's no doubting it when it happens.  Depending on the size they will catch fire and you'll smell a combination of copper and ozone.  It will give out a typical pulse signal however some of the pulses may be missing or it won't produce power at all.
1137722
Fuel, Heat, Oxygen - Also known as the traditional fire triangle.\n\nFuel - Something that can be burned\n\nHeat - The fuel must be heated to the point that it can burn.  Yes, it's true that once the fire starts it can and does generate it's own heat, but if that heat were removed somehow (i.e. the application of water), the fire goes out.\n\nOxygen - Fire's need oxygen to burn.  This is either the oxygen in the air, or from the chemicals that are burning, such as oxidizers.  If you were to interrupt the oxygen with say another gas, such as CO2 (as in a CO2 fire extinguisher), or blanket the fuel with dry chemical, a fire blanket, foam, etc., the fire goes out.\n\nThere is actually a fourth component to fire, and that's the chemical chain reaction itself.  Adding this forth component changes the fire triangle to a fire tetrahedron.  If the chemical reaction is halted, say by adding Halon, FM-200, FE-13, or some other gaseous fire extinguishing agent, the fire goes out. (and NO, halon does not "suck" all the oxygen out of the air, there's much more to it than that.)\n\nThat all being said, I like hatingmsn's answer that you may also need a permit!  HEHE... good one and may actually be a fifth component!
1146718
OH CAN IT EVER. It's call blue-flaming or torqing. You lay on you back and throw your legs back over your head as far as you can. Hold a lighter (not a match) near the butt-opening. If you get too close you create some risk. Build up a doozy and let 'er rip while the lighter is going. You have to exhaust the whole thing, or else you risk bringing some of the fire back inside of you while your butt-opening is still, well, open. So push it all out. Some of the flames can get huge. Just watch out for the "banana torq". It wraps around and burns bad things.
466768
Any grease fires. And you shouldnt rush to putting out a chemical fire with water unless you know what it is.
324722
The air surrounding the fire is heated. \n\nHot air is less dense than cold air.\n\nLess dense air goes up; while cold air replaces the hot air and is heated,\n\nThus a convection of air current is set up continuously giving the flame the obvious figure.\n\nBy blowing air through a nozzle we can change the direction of flame.
122399
Spontaneous combustion is real although it's causes are not understood.  I wouldn't spend too much time / effort worrying about suddenly bursting into flames though, it is extremely rare.  Aliens might exist although undeniable proof of their existence has eluded us up to this point.  It is likely that somewhere on one of the hundreds of billions of planets in our universe life could be and is supported.  I'm guessing we will never encounter them during our lifetimes, and probably not for thousands of years to come, but if we keep looking who knows what we will find, or what might find us.