About Fire... Is there an explanation for the flames?

[tangerine3]

Probably more off topic than on, but I was burning some twigs and rotten logs, when suddenly a question arose. Probably more of a science question. But is there really an answer?

The question is this: What are the flames made of? Yes, I know that they are the gasses from burning wood, or from gas or oil, or anything else that burns. These gasses mix with oxygen and burn. That is all understood. What is not understood is what is the actual flame that we see? They are usually yellow and orange and semi transparent. Or they are blue from natural or LP gas and also semi transparent. They emit light and heat. But what is the flame and why do we see it?

Maybe I'm getting too deep in my thinking about it. After all, its called FIRE, and maybe there is no further explanation. But the flames are real. They can be seen. Yet, what are they?

We know how the light from a lightbulb is created and florescent lights are different than filament types, because they produce ultraviolet light (which we can not see), but that makes the florescent particles glow. While we can explain how light is created from light bulbs, I've never gotten a real explanation about how fire becomes visible. Does it also produce ultraviolet? Is there some florescent type material in the gasses that make it glow?

[Tegger]

[e-mail] wrote in news: [e-mail]:

[Frank]

You'll have to read the url's in other answer.

Yellow flames are due to presence of sodium which is lacking in gas or oil flame although it only takes a trace.

[Stormin Mormon]

And, yes, the theory of phlogiston was revised a bit.

Cooking red mercury to provide dephlogistonated air, and all.

Christopher A. Young Learn more about Jesus

.

1. Long: Yours was a top question of scientific research in the

18th century, thereafter believed solved and thus abandoned, revived in the 20th century by the new technique of spectrum analysis, currently a hot topic today in astrophysics (because observing the flames is our chief source of data about other suns.) A good library (and PBS TV) can help you catch up concerning this.

[Steve Barker]

this sounds like one of them late night bar room conversations. "Imagine if our whole universe is just a speck of dust under the fingernail of some giant being...."

[Ed Pawlowski]

I see you got the answers, but let me add to this. Ever try to burn one log? Pretty difficult. Two is easy. You can watch the flame go back and forth as they feed off of each other.

[micky]

IIRC the light is caused by excited electons (or molecules?) which iirc gain energy during the combustion. I think you should read about quantum mechanics. Energy raises an electron to a high level and then the level drops again, not gradually, but by one (or sometimes more?) quanta iiuc, and when it drops, it give off light. Of course the next question is again, Why?.

This applies to chemical, incandescent, and fluoresent light, iiuc.

It seems every time a question gets answered, it leaves another question sthat isn't answered.

IIRC, I think the size of the quantum is determined by the material that is burning, and that determines the color of the flame.

They use a spectrometer to find the various colors of light coming from stars and maybe non-stars, and the mixutre and percentage of colors is what they use to announce what those things are made of.

[Dan Espen]

As you just explained, the process has to do with electrons being excited from one energy level to another and dropping back.

At one level there is more energy than at the other level. Since energy is neither created or destroyed, the change in energy level must be accounted for. What happens is that a photon (a unit of light) gets emitted or absorbed.

When you see a flame you are seeing photons being emitted.

[Jim Yanik]

Ed Pawlowski wrote in news: [e-mail]:

surface area is a big factor. that is why kindling is used to start a fire,more surface area. it's why steel wool burns.

[micky]

Yeah, that's it. Thanks for finishing my post.

[Doug]

Yes you are . Think more of safety instead !!

[Stormin Mormon]

100 or so years ago, there was the "soda cracker" theory. That we were just an atom in some big universe's soda cracker. The theory was met with a big, if some what nervous laugh.

Christopher A. Young Learn more about Jesus

.

this sounds like one of them late night bar room conversations. "Imagine if our whole universe is just a speck of dust under the fingernail of some giant being...."

[Dan Espen]

The phrase "solar energy" already has another meaning. The energy being released is due to the chemical reaction of oxidation. It's true that the tree grew using photosynthesis which is also a chemical reaction due to sunlight. So ultimately the energy did come from the sun.

The heat doesn't disappear, it gets diluted in the environment so you don't notice it anymore.

Photons on the other hand, just keep going until they meet another atom with electrons at a lower energy level that can absorb them. If they don't do that...well, you can see stars billions of miles away.

Photons, once released, instantly start moving at the speed of light and have no problem traveling immense distances.

All of this is explained in overwhelming detail at Wikipedia.

[krw]

So are coal and oil, as the accepted theory goes, anyway.

Ditto for coal/oil, but from millions of years back.

Energy + matter cannot be destroyed. By burning wood, you're converting matter into energy. Certainly you've heard of E=mc^2?

[Han]

" [e-mail]" wrote in news: [e-mail]:

Ummm, I was taught that burning is oxidation, such as C + O gives CO, CO2, etc. In releasing carbon from the organic compounds in wood and combining with oxygen no net mass changes are made. All of the wood matter plus the oxygen weigh exactly the same as all of the combustion products combined. The generation of new bonds between C, H, S, whatever and oxygen constitute "exo-thermic" reactions, i.e. generating heat and thereby also light photons of various wavelengths, visible and infrared, but nothing close to Xrays or gammarays.

E=mc^2 refers to nuclear reactions where mass and energy are interconverted, mostly matter into energy. This generates vastly greater quantities of energy than mere burning.

[krw]

Wrong. Chemical bonds have mass. You've obviously not heard of E=mc^2?

Nope. See above. The resultant mass is less than the mass going in, by, you guessed it, E=mc^2.

Light is light; energy is energy. The wavelength doesn't matter. It's just a matter of magnitude. Give that you've never come across Einstein, I suppose you haven't heard of Max Planck, either: E=h*nu (energy = constant * wavelength)

Energy isn't created out of thin air (well...) in a chemical reaction, either. I suggest you go back and study high school physics. E=mc^2 is not just a good idea...

[micky]

This is one more example of "In a closed sytem, entropy is always increasing."

Entropy is a measure of the disorganization of the system. Before the fire, the energy and mass we're talking about was all located in the wood. After the fire, the energy has one every which way, some being absorbed by the things the light hits, some by the ground under the fire, some by the air above the fire, and most of all that continues to dispers. The mass, mostly carbon and other elements, dispurses to a C02 and maybe some CO.

I guess the only thing that increases the orgianization of the earth is the sun, but the sun is becoming disorganized as its energy goes off in all driections.