What are the properties of fire?

[wasteofo2]

Anyone?

 

[Integral]

Flames are the result of oxidation reactions which essentially vaporize the burning material. The vapors resulting from this chemical reaction contain many atoms with electrons in highly excited orbitals. Flames are the visible light emitted by these electrons decaying to lower energy levels. This also explains why different chemicals (materials) have different color flames. The flame colors are determined by the chemical composition of the burning material.

 

[wasteofo2]

You guys make it seem so simple, it's like listening to Robert Johnson...

 

[Moni]

Originally posted by Integral
The vapors resulting from this chemical reaction contain many atoms with electrons in highly excited orbitals. Flames are the visible light emitted by these electrons decaying to lower energy levels. This also explains why different chemicals (materials) have different color flames. The flame colors are determined by the chemical composition of the burning material.

Integral would you clear few things more?

1) After oxidising from where the energy comes to excite the electrons?

2) Different chemical materials has different color flames that means they emitts waves of different wave lengths? then how that is possbile...that the wave lenghts change?

3) Why color depends on the chemecal composition of the burning materials?

 

[Integral]

The chemical reaction releases energy so is self sustaining once started. You use a match to light a piece of paper on fire, the energy supplied by the match starts the reaction, once the reaction is started it releases energy stored in the chemical bonds. The released energy is sufficient to keep the reaction running plus enough extra to provide heat to the surroundings. The reaction which rips apart the chemical bonds must leave many electrons in the constituent atoms in an excited state. These would be the electrons which were initially involved in binding the combustion molecules together.

The dependence of the emitted wavelengths on the chemical is a result of Quantum Mechanics. Every element has a given electron structure, this structure determines the wavelengths that are emitted as electrons cascade to lower energy levels.

 

[Moni]

Originally posted by Integral
The dependence of the emitted wavelengths on the chemical is a result of Quantum Mechanics. Every element has a given electron structure, this structure determines the wavelengths that are emitted as electrons cascade to lower energy levels.

Quantum Mechanics! But I heard according the QM energy is considered as small Packets...and I mean it deals with particle properties not the wave! May be I am wrong not sure... :(

 

[Integral]

When we are dealing with light Quantum Mechanics tells us that the energy of a photon must be of the form

$$E= nh\nu$$
Where
$$E = Energy$$
n is an integer
$$\nu= frequency$$
Rearranging we have
$$\nu=\frac E {nh}$$
The various electron orbitals in an atom are separated by discrete steps of energy given by the above equation. When an electron changes from one orbital to another there must be a photon emitted (or adsorbed) with the same energy which separates the 2 orbitals. Can you see that the frequency of the emitted photon is determined by the Energy?

Photons of different energies have different color because frequency is what determines the color of light. A photon cannot be considered a particle like a baseball is a particle, it needs be see as some form of a wave packet of energy. The Frequency or wavelength of the encapsulated energy is determined by the amount of energy encapsulated.

 

[losang]

Fire is that which is hot and burning. Why do you need to explain it in terms of atoms and electrons. Do you think that cave men didn't know what fire was?

 

[Jimmy]

Wasteofo2 already knew that fire was hot and burning. He was looking for the type of answer that Integral gave. He seemed satisfied with the answer. This is a physics forum, after all.

 

[losang]

In that case the question should have said 'how do you explain fire from a physicists point of view?' or something similar.

 

[Jimmy]

When you ask a question on a physics forum, you can expect the answer to be from a physicist's point of view. Like I said, wasteofo2 didn't seem to be upset by the answer. Why are you?

 

[Njorl]

That's pretty much understood. When I post on the caveman forums it is understood that I want things explained in caveman terms.

"Fire BAD!"
"Fire good"


Njorl

 

[Jimmy]

Originally posted by losang
In that case the question should have said 'how do you explain fire from a physicists point of view?' or something similar.

You wouldn't happen to be an enlightened Buddhist, would you?

 

[Integral]

Originally posted by losang
Fire is that which is hot and burning. Why do you need to explain it in terms of atoms and electrons. Do you think that cave men didn't know what fire was?

This is not an answer to what is fire. When I touch the stove top my finger is hot and burning, so does that mean my finger is fire?

 

[lan418]

How do they make flamethrowers?

 

[losang]

Originally posted by Integral
This is not an answer to what is fire. When I touch the stove top my finger is hot and burning, so does that mean my finger is fire?

Your finger is not burning because if you remove it from the stove it does not have the ability to maintain the heat. It is only experiencing the pain from touching the hot stove.

 

[Mr. Robin Parsons]

Originally posted by losang
(SNIP) Do you think that cave men didn't know what fire was? (SNIP)

Sure Cavemen knew, they thought it was "Hot and Burning"...but the Question was: "What E-X-A-C-T-L-Y is it" hence the obvious request of a "detailed (more then cave knowledge) responce" cause clearly the cavemen/women DID NOT know the explanation Integral has given...leading edges of knowledge...

 

[Integral]

Originally posted by losang
Your finger is not burning because if you remove it from the stove it does not have the ability to maintain the heat. It is only experiencing the pain from touching the hot stove.

Here is the trouble with your definition, we have different ideas of what burning means. You have NOT defined the key concept. Just ASSUMED it means the same to you as to everyone else. When I have been in the sun to long I get a sun burn, the skin continues to feel hot and burning for hours after I get out of the sun. Now, what do you mean by hot? What do you mean by burning? Your definition does not provide an answer. Only more questions.

 

[losang]

Originally posted by Integral
Here is the trouble with your definition, we have different ideas of what burning means. You have NOT defined the key concept. Just ASSUMED it means the same to you as to everyone else. When I have been in the sun to long I get a sun burn, the skin continues to feel hot and burning for hours after I get out of the sun. Now, what do you mean by hot? What do you mean by burning? Your definition does not provide an answer. Only more questions.

It does provide an answer. It answers the question of what is fire. Just because questions arise about the meaning of words in the definition does not negate the fact that it answered a question.

 

[russ_watters]

Originally posted by losang
Your finger is not burning because if you remove it from the stove it does not have the ability to maintain the heat. It is only experiencing the pain from touching the hot stove.

Sure feels like its burning to me. The sensation hasn't changed, so how do I know it isn't burning anymore?

Science has to be more specific than you are being, otherwise our understanding of phenomena decreases with every answer.

In that case the question should have said 'how do you explain fire from a physicists point of view?' or something similar.

I realize you're new here, but how did you miss the name of the forum? In any case, we do have a philosophy forum here - perhaps you'd be more comfortable there.

How do they make flamethrowers?

A flamethrower is a squirt gun with a lighter in front of it. They squirt a flammable liquid (probably something similar to napalm). definition does not negate the fact that it answered a question.

 

[losang]

Originally posted by Mr. Robin Parsons
Yup! DIFFERENT METHODS!...physics requires substantiable proofs, Philosophy, NAH!...BIG DIFFERENCE! (this, apparently, you couldn't figure out!)

Again you show your limited understanding of both physics and philosophy and I accept neither. In both disciplines there are times when the evidence presented is based on proof and times when it is not. Your generalization of physics as requiring substantiable proof and philosophy not is too broad a generalization to hold everywhere.

Secondly, I have been avoiding the issue but you haven't even defined what you mean by philosophy.

 

[Integral]

If you wish to continue this disscussion please to so here