what element is "fire" ?

[veton]

Just woundering about fire?

what element is that, eg. solid,liquid,gas,etc

 

sorry I don't know if its the right section

[iNow]

I think what you mean when you say "element" is instead better described as "state of matter."

 

In that case, fire is an interesting fourth form of matter (not solid, not liquid, not gas) which is called a plasma.

[insane_alien]

to expand on what iNow is saying, a plasma is a charged gas. that is to say, not all the electrons are bonded to the atoms. this causes a lot of light to be emitted as electrons rejoin the charged atoms as they cool down.

 

in a normal candle flame this happens to be in the visile range but this is not always the case and you can have an invisible flame.

[swansont]

Not to be too pedantic, but fire is a process or reaction (one type of oxidation we call combustion). A flame is (partial) plasma.

[YT2095]

the way I was told when I asked many years ago is that a flame is simply Gases so hot that they Glow.

[frost]

the way I was told when I asked many years ago is that a flame is simply Gases so hot that they Glow.

Yeah my chemistry teacher also defined fire as "glowing gas".

[insane_alien]

depends on the flame really. you can get a cold blue flame which is too cold to glow blue but it does anyway because of electron interactions. that one is definitely a plasma. in a candle flame it is a plasma because if you actually look at a cross section it is perfectly transparent in the middle(where it would be hottest) and only around a 1mm thickness glows. this is where the plasma exists.

 

i can't remember the exact temperature at which air goes opaque but i think it is up there at 3000K

[Farsight]

Just woundering about fire?

what element is that, eg. solid,liquid,gas,etc

 

I am hugely tempted to say:

 

Why, fire is its own element. Like the saying goes: earth, air fire and water. Surely everybody knows that?

 

But I won't. Sigh:

 

Fire, or as swanson says, flame, is a mixture of gases and particulate solids, usually incandescent, wherein some portion of the gases can be considered a "plasma". Don't worry about plasma. When the gases and particulate solids cool down a bit and stop glowing, we call it smoke.

[YT2095]

When the gases and particulate solids cool down a bit and stop glowing, we call it smoke.

 

no WE don`t!

 

there`s no "Smoke" from my Bunsen flame, only H2O and CO2, they would when cooled down be called a Gas and a Vapor, Not "smoke"!

 

smoke does Not need Fire or flame, it is a Different entity entirely and partly related to particulate matter (that was never asked about!).

[thedarkshade]

the way I was told when I asked many years ago is that a flame is simply Gases so hot that they Glow.

Yeah I was told too that fire is a "reddened" gas!

 

I agree with YT2095! There's no smoke in the oxidation of glucose either. You guys might think that what I'm saying (oxidation of glucose) is stupid and has nothing to do with fire, but they're actually the same thing (just some slight differences)! The differences from pure fire and glucose oxidation is that, in fire that occurs in nature the energy is released explosively and that causes the increase in temperature (more exact heat), but in glucose oxidation the energy is released step by step and in the presence of water. And there is nothing wrong by saying that glucose oxidation is actually a process of burning glucose!

[MrMongoose]

I can't help but think that those who just said it was a plasma were trying to make hings sound more sciency at the expense of being correct. Generally it'll be a gas.

[insane_alien]

I can't help but think that those who just said it was a plasma were trying to make hings sound more sciency at the expense of being correct. Generally it'll be a gas.

 

no, there are free electrons and free radicals, it IS a plasma. regardless ofhow 'sciency' it sounds.

[MrMongoose]

But thats not the case... Fire is just hot gas (there might be amounts of solids, liquids, plasma in it). There will be electrons moving when combustion products are formed, but generally they will not move freely unless there is a lot of energy. That is, fires can contain plasmas if they're very hot, e.g. rocket exhaust, but GENERALLY it is not right to assume that a fire contains any more plasma than a block of ice.

[Klaynos]

Can we agree to use the terminology put forward by Swansont in his pedantic post, just to be clear about what we're talking about (i.e. flames not fire)?

[insane_alien]

But thats not the case... Fire is just hot gas (there might be amounts of solids, liquids, plasma in it). There will be electrons moving when combustion products are formed, but generally they will not move freely unless there is a lot of energy. That is, fires can contain plasmas if they're very hot, e.g. rocket exhaust, but GENERALLY it is not right to assume that a fire contains any more plasma than a block of ice.

 

stick a flame in an electric field and tell me it isn't a plasma. if it were gas it would be unaffected. plasmas are strongly affected though. you can even extinguish a flame with an intense enough field.

[MrMongoose]

Well as I said there are small amounts of plasma for very short periods of time in any flame, and an electric field could affect those consecutively. Though you need a pretty strong electric field and a pretty hot flame to get that to work.

 

That doesn't change the fact that the majority of the flame is gas.

 

Take a simple analogy... If you have a cup of water, its likely to have a small layer of vapour sitting on its surface. Put a fan (a field generator of another kind) by its side to blow off the vapour layer reducing the humidity and vapour will form from the water more quickly. So over a period of time the water becomes "extinguished".

 

So the argument comes down to whether youd be willing to accept that a cup of water is generally liquid (ignoring the cup itself).

 

I'm perfectly happy to admit that flames with enough energy will have large amounts of plasma and that all flames will have some plasma in them. "Flames are plasma" doesn't really say that though.

[Riogho]

Actually, blowing a fan doesn't make water vapor produce quicker, it's just when a water molecule escapes the puddle it is in, it is of course more dense then air, so it usually falls back in.

 

The moving air just helps it not fall back in by pushing it away before wonderous gravity takes effect.

[MrMongoose]

Blowing the fan will move existing vapour sideways so that it doesn't fall back into the cup but rather down the to the cup's side. The air remaining above the cup will be drier, so more vapour will be produced to establish equillibrium at the water's surface.

[Mr Skeptic]

I just read that carbon subnitride (C4N2) has the hottest flame at a whopping 5260 K!

[veton]

ok guys

i understand now

 

i though fire is more likely, a gas

 

Thanks guys