Are flames matter?

Post Reply New Topic

Are flames matter? I'd say if they are, they sure as heck behave differently from other matter.

Flames are hot gas. The temperature is high enough to cause the hot gases to glow.

Please see: http://en.wikipedia.org/wiki/Flame

ruveyn

Sometimes flames are plasma.

Also, have you ever seen a picture/video of flames in space? You should. They don't behave like flames on earth. It's cause of the gravity.

There are different types of flame . Normal orange flames are actually tiny incandescent soot particles that haven't yet undergone complete combustion. In this case the actual combustion reaction takes place on the very edge of the flame, just beyond where you can see the orange flame. The soot particles that make it through this zone without undergoing combustion become smoke particles.

Blue flames OTOH are produced by completely vaporized fuel that has become hot enough to be ionized. A very intense pure blue flame is made up entirely of C2 and CH radicals in a plasma state. A blue flame doesn't produce any smoke because all the hydrocarbons have vaporized into the smallest vapor molecules, leading to an efficient combustion reaction such that no non-oxygenized carbon is able to "exit" the flame.

Flame (or fire I suppose) is an exothermic gaseous form, which is yet, Matter.

I suppose Flame is hot enough that it can be considered Plasma, which is in and of itself a form of matter.

In a free-falling frame of reference there is no gravitation. A free falling reference frame is as close to an inertial frame of reference in empty space as one can get.

ruveyn

No. They are not.

Flames are heated gas... Plasma is a separate phase of matter. Plasma can cause flames, but it is not, in itself a flame.

Yes, but sometimes that gas gets hot enough that it is ionized, making it a plasma.

Which does not contradict my statement...

Once that gas reaches the plasma stage, it ceases being a flaming gas and becomes plasma. I was not disputing that flames can (in rare cases, create plasma)...

I guess it depends on the definition of a flame.

What people visibly see and call a flame in everyday life is either a gas or a cloud of fine particulate matter that's gotten hot enough to emit radiation in the visible spectrum. Gases usually have a finite number of discrete quantum energy levels and thus emit a discrete number of possible wavelengths. Pure C2 and CH molecules undergoing combustion produce blue flames. Large molecules or solid particles have a much more randomly distributed number of possible energy levels and thus emit like a black-body such that the wavelength spectrum is entirely dependent on temperature with little dependence on exact composition. When large hydrocarbon molecules in a combustion flame aren't fully broken down, due either to inadequate temperature or inadequate supply of oxygen, the combustion process is incomplete. Incomplete combustion emits a more random spectrum of photon wavelengths and thus produces a color that is mostly a function of temperature and tends to appear between red, orange, and white. A common flame is a mixture of complete and incomplete combustion and thus has both blue and orange parts to it. A jet engine or welding torch uses fuel that's been premixed with oxygen, thus there is no incomplete combustion and the flame is purely blue.

Technically any matter that's a significant temperature above absolute zero emits radiation, just not usually in the visible spectrum. It's also possible for cooler gases to emit light yet not be considered a flame. Not to mention a lot of flames contain not just gas but particles in the form of soot. So just any glowing gas is not a great definition of what a flame is. A better definition might be any rapid exothermic reaction occurring in either a gas or mixture of gas and solid particles. In this case some rare flames produced by rare reactions might be completely invisible if their emission bands fall completely outside the visible spectrum.

My short answer is a flame is not matter but a process involving matter. The energy emitted by the process is what you see. The combination of movement of the gas via convection and diffusion plus movement of the reaction zone itself relative to the gas is what governs the visible motion and behavior of the flame.

Another way to explain it... would you describe a wave in the water as a liquid or as a process occurring in a liquid medium? A flame is simply a type of chemical process occurring in a gaseous medium. It's an exothermic process producing a great deal of heat and light in a localized reaction zone.

I know it is nitpicky, but a properly tuned jet engine, under normal operating procedures should not have any open flame externally...

That being said, to produce maximum thrust in many applications, an engine may be burned "wet" (after burners engaged), during which additional fuel is pumped into the exhaust, thereby increasing thrust dramatically. Those flames are rarely blue...

[img][800:630]http://www.rcjetshop.co.uk/media/wysiwyg/rcjetshop/content-images/Afterburner-RC-Jet-4.jpg[/img]