Whats fire made of? What element atoms are it.?

[aditya23456]

why does peak of fire of a matchstick face upwards ie away from ground.why is it not effected by gravity,is there any reason other than pressure considerations.

 

[Borek]

It is affected by gravity which is why it is pointing up. Buoyancy being the key word.

 

[Dickfore]

The flame is a state of matter known as plasma.

 

[Lsos]

Someone correct me if I'm wrong, but the flame is not made up of any particularly special atoms or substance. It is simply a regular substance, such as air, that has been heated to the point that it releases light.

 

[Borek]

You are right about "nothing special", but it is not "just air". Think combustion products.

 

[HallsofIvy]

A large part of a flame is carbon dioxide (or if the fire is "starved of oxygen" carbon monoxide). And it is affected by gravity but hot gasses are less dense than the colder air around them.

 

[Antiphon]

It's made of the vapors of the burning object plus oxygen from the air.

 

[Borek]

It's made of the vapors of the burning object plus oxygen from the air.

So there is no combustion products in the flame? If so, where does the energy heating the flame comes from?

 

[mkillman]

fire is light emitted by the excited atoms of the material when excited to the point of combustion

Heat = light = magnetic radiation just on a diffrent frequency

 

[Borek]

fire is light emitted by the excited atoms of the material when excited to the point of combustion

No. Fire is not just a light.

 

[mkillman]

what you "see" and "feel" as fire is simply radiation visible light and infrared

Aside from smoke and other random particles but the "flame" is nothing more then light from atoms that have been excited to the point where they begin an exothermic reaction with the air around them

Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing heat, light, and various reaction products.[1] Slower oxidative processes like rusting or digestion are not included by this definition.
The flame is the visible portion of the fire and consists of glowing hot gases. If hot enough, the gases may become ionized to produce plasma.[2] Depending on the substances alight, and any impurities outside, the color of the flame and the fire's intensity will be different.

http://www.cbsnews.com/8301-504784_162-20106378-10391705.html

 

[aditya23456]

can a flame be in such a way that it gives out only light of frequencies other than visible light..I meant flame exists but its hardly visible to human eye

 

[mkillman]

yes there are several materials that burn off into UV instead of visible light

 

[Borek]

the "flame" is nothing more then light from atoms that have been excited to the point where they begin an exothermic reaction with the air around them

What about hot soot that is no longer reacting due to the lack of oxidant, but still emitting the IR/light just because of its high temperature? It doesn't fit this definition.

Fire is the rapid oxidation of a material

The flame is the visible portion of the fire

Even assuming your original answer was technically correct, it addressed only what the flame is, while the question is about fire. You listed definitions of fire and flame, so you know these are two different things, but you still insist your partial answer is the correct one?

 

[Dickfore]

yes there are several materials that burn off into UV instead of visible light

like what?

 

[Delta Kilo]

can a flame be in such a way that it gives out only light of frequencies other than visible light..I meant flame exists but its hardly visible to human eye

Note how hydrogen flame from the main engines is almost invisible, especially in comparison with solid propellant SRBs.

 

[HallsofIvy]

Someone correct me if I'm wrong, but the flame is not made up of any particularly special atoms or substance. It is simply a regular substance, such as air, that has been heated to the point that it releases light.

You are right about "nothing special", but it is not "just air". Think combustion products.

Lsos didn't say "just air", he said "such as air" which allows other things.

It's made of the vapors of the burning object plus oxygen from the air.

So there is no combustion products in the flame? If so, where does the energy heating the flame comes from?

Antiphon said "vapors of the burning object" which Merriam-Webster defines as "diffused matter (as smoke or fog) suspended floating in the air and impairing its transparency"

 

[mkillman]

pure magnesium burns into some uv light along with visible light
and i believe so does methanol

Wild-land firefighters occasionally come across this phenomenon where its "on fire" but burning so cold that the flame is not visible to the naked eye

 

[Dickfore]

If it is burning cold, then it should radiate even less in UV than normal fire. As for Mg, you said yourself its flame is visible, so these examples are invalid.

 

[K^2]

Flame from most organic fuels, like wood, candle, gasoline, etc., is primarily glowing soot. Products of combustion are translucent gases, meaning they aren't going to emit much via black-body. Soot, having very high absorption coefficient is also very good at emitting radiation.

I'm not sure about natural gas burners, to be honest. But if a gas burns clean, the flame is not going to be very visible. Case in point,

Note how hydrogen flame from the main engines is almost invisible, especially in comparison with solid propellant SRBs.

Enthalpy of formation of H20 is -242kJ/mol. That's enough to heat water vapor to at most 7k K. (Realistically, significantly less.) This is still well within visible band. The reason you don't see the flame is because it also happens to be very close to the minimum in absorption spectrum for H2O, so the emission intensity is very low.