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Why is water not flamable?

Posted on 2003-03-31
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Hydrogen is highly flamable element.
Oxygen helps produce fire.

Then, why is H20 not flamable?
it contains 2 hydrogen and 1 oxygen.
why is that?

I give the points to the most convincing.
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Question by:Jerry_Pang
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55 Comments
 
LVL 17
ID: 8238009
You need to add energy to the water so as to separate the atoms before they can recombine and 'burn' (The hydrogen burns by combining with the oxygen).
If the amount of energy you need to add to seperate the atoms is greater than the energy given off by the recombining reaction then the substance won't burn.


..or it may have burnt when you heated it but as the end result is water then it might be hard to tell.
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by:grg99
ID: 8238056
Water is the ashes you get when you burn hydrogen and oxgen.

Ashes don't burn, if they did, they wouldnt be ashes (yet).

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by:billious
ID: 8238405
Hmm...flammable is an interesting word.

Until the early 1970's the word 'INFLAMMABLE' meaning 'can become inflamed' was applied to substances that burned readily.

Rather than teaching the few people who insisted that IN always means 'not' as a prefix and who were somehow unable to fathom why a warning sign needed to be placed on such substances warning that they COULDN'T be set afire with a flame (like INERT substances can't) some people started insisting that everyone else use the term 'flammable' because it sounded more like the message they were trying to convey.

"FLAMMABLE" was the word that applied to such substances as Ammonium Perchlorate or white Phosphorous, which spontaneously combust when exposed to air. Naturally, having stolen this word, these people haven't bothered to coin a replacement since they appear not to be capable of recognising the difference.

So what if it has nothing to do with the Hydrogen argument?
...Bill
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by:andyalder
ID: 8238413
Water IS flamable. Get an evacuated belljar and a lump of sodium and heat until sodium becomes a gas. drop water into the jar via a pipette and you will see the water droplets bursting with a flame.

2 Na + 2 H2O > 2 NaOH + H2
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by:Jerry_Pang
ID: 8238924
"If the amount of energy you need to add to seperate the atoms is greater than the energy given off by the recombining reaction then the substance won't burn."

hmmmp.. =).is this why things burn?

"see the water droplets bursting with a flame." - i too have my own version of this, and i cant explain it. I remember this question when i was still a kid. Playing with candles and cooking any insects(<grins> really! we were camping and have nothing to do. Mosquitos, bugs, roaches, grasshopers, moths, etc.)

(WARNING! - dont try this at home. )
Boil the candles for awhile (about 2 minutes) until a fire appears above the melted-boiling-(candle/wax)-thing. When this fire appears, drop a droplet of water into the fire and see it burst into fire. The more water you drop the BIGGER THE FIRE! WARNING!!! we tried dropping a can of water, the fire reached about 5-10 feet high(no kidding).
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by:Jerry_Pang
ID: 8238998
i mean, why does it burst in fire when if we put water? we tried to put out the flame with water but it burst into flames.
Later, i realize, water = Hydrogen2 Oxygen. Hydrogen a highly flammable element, and oxygen which helps fire.
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by:andyalder
ID: 8239038
When you pour water onto burning wax the water doesn't catch fire, it simply evaporates explosively taking the burning wax with it and spreading it about - all over you if you're not careful.
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LVL 17
ID: 8239119
>is this why things burn?

If the energy given off by the reaction is greater than the energy needed to keep the reaction going things will burn.

candles: I've seen this done with a cup of water and a tray of burning parafin/kerosene. It produced a fireball about as big as a house. Fire safety demonstration showing how not to put out a fat fire in the kitchen.
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by:andyalder
ID: 8239470
Yup, it produces a form of BLEVE.
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by:keneso
ID: 8240069
because if it was we should have looked for another element to turn off the fires

too much work in so little time ... therefore h2o can't be flamable ;)
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by:SunBow
ID: 8240230
Cook(?) view>  Water does burn, covertly.  I've proven it often, simply putting a pan of water on the stove. While I watch it, it just sits there in the pan. But if I turn my back and leave the room, when I return I find only empty pan, the water burned when I was not looking. I burn water.

Theoretical view>  Water is the end product of Hydrogen burning. Burning, is adding oxygen to something, perhaps under duress (ignition).

Child view>  Water can't burn. Children learn about  how water puts out fire (fire, earth, air, water game) shortly after learning rules for "rock, paper, scissors". So they know that as soon as any teeny hydrogen wants to burn, the water puts it out before it can be noticed. But also due to the nature of childhood, the kids quickly forget, as one plays scientist and tosses a rock into the water and it <kerplunk> falls to bottom leaving big splash and a wake, then watches as the next kid tosses a stone and it skips <bouncy> across the surface. At least that's how I forgot the rules.

Experimental View>  Water does burn if you isolate it into smaller pieces, from the mass that would extinguish fire. Take a brick of Sodium. Rather dull finish unlike most metals. With tiny eyedropper, release a drop of water on the brick. Oh, it just sits there (I think we did that). You see, the atoms in the molecule are also fairly ignorant. Now, take a very small knife with a stiff razoe sharp blade. Slice off a small sliver of the metal. Look at what the blade did to the metal, making it very shiny. Stand back and drip a drop of water on the shiny part. The two hydrogens will now see reflection of themselves and notice they share a sole oxygen atom. A catalyst of envy ensues, and as they battle for each other over their mate, flames of high temperature erupt signifying the heat of their battle. (since this is similar to andyalder, let me add that we did it with Potassium as well, except for dripping on the brick before the blade used). As you desribe this to TheEnemy, you might drop hint that one could gain fame by trying experiment of dropping the whole brick in a bucket of water. If they try it, they'll soon be found listed in more than one section of the newspaper, a sure road to fame.

[note, this is not the science TA, so none of what I mentioned is for others to emulate, and the chemistries mentioned above should be studied well before attempting any demonstration or experiment. Well, except for the part about skipping of solid rocks off a liquid surface.]
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by:SunBow
ID: 8240291
[on the shiny metal with dull finish, the outer layer was already oxidized = rusted. Thus the drop should not cause the flame until exposed to non-rusted area of the sample. Once the sample is aflame, to put it out you use forceps and drop into belljar of liquid - ? I forget, it may have been alcohol? Naw, couldn't be. But you might have a lid on the side to cap it, to snuff the airborn oxygen from keeping the experiment in progress]
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by:SunBow
ID: 8240357
[sheesh, some make it more complicated, talk about ading extra variables:  http://www.allatoms.com/unit2a/E2.3-Sodium.doc]

Experiment #2.3: What Happens When Sodium Goes Swimming in a Trashcan

Introduction:

      In this experiment, we will study the series of reactions that begin when sodium metal is placed in water. These reactions will give us a bountiful opportunity to apply the principles of thermodynamics that we have been studying and make some predictions about the behavior of the atoms involved. This reaction can be quite violent and dangerous especially using the quantity of sodium (25-30 g) that we will use. The experimental set-up will allow us to observe the reactions safely and to collect data that we can compare to some of our predictions.  

Experimental Set-up:

            A large quantity of water will be measured and placed in a small, plastic trashcan. Phenolpthalein will be added to the water. The small trashcan will be placed inside a large metal trashcan. A probe interface will be set-up to collect pH and temperature data and will be placed in the metal trashcan. The sodium metal will be massed and placed in a zip-lock bag. Two holes will be made in the bag. A hole at the top of the bag will allow us to tie the bag with kite string. A hole at the bottom will allow the other reactant to enter the bag. There is a hole in the lid of the metal trashcan. This will allow us to slip the kite string through the lid and hold the sodium bag above the water while the lid of the metal can is closed. We can back up to a safe distance and cut the string when we are ready.  
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by:Itatsumaki
ID: 8240926
This depends on what you mean by "flammable".  I take a combustion reaction to be one in which the substrate becomes oxidized with gaseous O2.

How would you oxidize H2O further?  You can't.  You can do some reductions, as noted above.  But that isn't combustion according to the a simple definition that ensures "burning paper or gas" is combustion.

In short: by definition you can't oxidize the hydrogen in water anymore, so it cannot be combusted.

===========================================
I imagine somebody could create some sort of an esoteric species with a three-center two electron bond joining the hydrogen to two oxygens.  Who cares?  It wouldn't be stable under normal circumstances anyways.
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by:andyalder
ID: 8241058
Amazing that they can get a large quantity of water into a small trashcan without getting wet feet but anyway it's burning a solid in water rather than burning the water itself.

We need to work out what Jerry means by flamable. Since there is no such word I guess that they mean to be able to produce a flame by burning. It's as good as the dictionary definitions that refer to flammable as meaning combustible or burnable and the definitions of those words just mean inflammable - cyclic definitions. At least there is a decent definition of flame as being the incandescant gas produced by burning a substance in a gas - thanks billious.

That's why I suggested burning water in a gas rather than reacting a solid with water, I admit that it was only a thought experiment, it would need a sealed vessel full of hot sodium or some other violent gas that I could drill a hole into to let the water in and they aren't easy to find.
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by:rrhunt28
ID: 8241908
How about using the word volatile.  That is more acruate if you are talking about chemistry.  It means substances that evaporate quickly.  AKA gas, alchohal.  

The reason your fire went wild when you threw water on it is because you where spreading out the wax in liquid and gas form.  

Here's the sequence of events in a typical wood fire:

Something heats the wood to a very high temperature. The heat can come from lots of different things -- a match, focused light, friction, lightning, something else that is already burning...

When the wood reaches about 300 degrees Fahrenheit (150 degrees Celsius), the heat decomposes some of the cellulose material that makes up the wood.

Some of the decomposed material is released as volatile gases. We know these gases as smoke. Smoke is compounds of hydrogen, carbon and oxygen. The rest of the material forms char, which is nearly pure carbon, and ash, which is all of the unburnable minerals in the wood (calcium, potassium, and so on). The char is what you buy when you buy charcoal. Charcoal is wood that has been heated to remove nearly all of the volatile gases and leave behind the carbon. That is why a charcoal fire burns with no smoke
The actual burning of wood then happens in two separate reactions:
When the volatile gases are hot enough (about 500 degrees F (260 degrees C) for wood), the compound molecules break apart, and the atoms recombine with the oxygen to form water, carbon dioxide and other products. In other words, they burn.
The carbon in the char combines with oxygen as well, and this is a much slower reaction. That is why charcoal in a BBQ can stay hot for a long time.
A side effect of these chemical reactions is a lot of heat. The fact that the chemical reactions in a fire generate a lot of new heat is what sustains the fire.
Many fuels burn in one step. Gasoline is a good example. Heat vaporizes gasoline and it all burns as a volatile gas. There is no char.

Humans have also learned how to meter out the fuel and control a fire. A candle is a tool for slowly vaporizing and burning wax.
In the last section, we saw that fire is the result of a chemical reaction between two gases, typically oxygen and a fuel gas. The fuel gas is created by heat. In other words, with heat providing the necessary energy, atoms in one gaseous compound break their bonds with each other and recombine with available oxygen atoms in the air to form new compounds plus lots more heat.
Only some compounds will readily break apart and recombine in this way -- the various atoms have to be attracted to each other in the right manner. For example, when you boil water, it takes the gaseous form of steam, but this gas doesn't react with oxygen in the air. There isn't a strong enough attraction between the two hydrogen atoms and one oxygen atom in a water molecule and the two oxygen atoms in an oxygen molecule, so the water compound doesn't break apart and recombine.

The most flammable compounds contain carbon and hydrogen, which recombine with oxygen relatively easily to form carbon dioxide, water and other gases.

From howstuffworks.com

There you have it folks.


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by:MusicMan
ID: 8242122
I feel silly now - all these clever answers and I thought it didn't burn 'cos it was wet.

Oh well.
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by:billious
ID: 8242389
MusicMan:
  So your contention is that only non-wet substances, like Mercury, for instance, burn?

...Bill
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by:Jerry_Pang
ID: 8242422
"I feel silly now - all these clever answers and I thought it didn't burn 'cos it was wet.

Oh well. "

HAHAHAHA! after reading all the clever answer then reading this. LOL..


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by:Jerry_Pang
ID: 8242429
"There isn't a strong enough attraction between the two hydrogen atoms and one oxygen atom in a water molecule and the two oxygen atoms in an oxygen molecule, so the water compound doesn't break apart and recombine. "

good thought.

Flamable  - meaning producing fire/flame.

What sould be mix to water then to make it flamable?
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by:Jerry_Pang
ID: 8242533
how do make hydrogen burn?

To make hydrogen fuels, they extract hydrogen from h20. WHy? whats wrong with h20?
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by:esmogen
ID: 8246284
It's because the molecule of water has a strong polar covalent bond due to the small difference in electronegativity of oxygen and hydrogen atoms.

Burning is a reaction with oxygen, and since the bond is already there, no go.

It is similar to two people totally in love, and a third party comes along. The bond is already strong between the two (molecule), so no new relationship(reaction) will be formed.

Explaining what's said with new words, and a neat analogy to help the understanding.
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by:billious
ID: 8246426
Covalent Bond?
Electronegativity?

Rubbish.

Water doen't burn because if it did you couldn't have a cup of tea in safety. Or coffee. Even Beer. But don't drink beer from cups. That's tacky.

...Bill
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by:Itatsumaki
ID: 8246625
Jerry,

Hydrogen burns by being oxidized:
2 H2 + O2 --> 2 H2O

The only by product is water (vapour, usually; possibly steam; never aqueous that I know of).

So if you extract H2 from water, then burn it your reactions are:

2 H2O --> 2 H2 + O2
2 H2 + O2 --> 2 H20

Notice those equations are the same, just written in reverse?  By all thermodynamics you can't get energy for "free" out of a cyclic process.

So why is hydrogen extracted from water before use as a fueld source?

Two answers:
1) It usually isn't: fuel hydrogen more often comes from hydrocarbons like methane.
2) H2 is a clean fuel source.  It is thought to be more efficient to have H2 generated at a central station and then distributed to (e.g.) cars for local consumption than to have CH4 (methane) burned in cars.

Finally, as has been noted above, the polarity of the OH bond in H2O reduces the energy content of H2O significant over the separate gases.  The reaction is *not* spontaneous in general (it has bad kinetics, partially because it requires conversion of 3 moles of gas to two moles of liquid -- a bad entropy characteristic for spontaneity!).

Nevertheless, the reaction:
2 H2 + O2 --> 2 H2O
releases an enormous amount of energy, with an enthalpy of nearly 300 kJ -- that's about as strong as the strongest covalent bonds.

So in summary, water doesn't burn because:
a) the polar OH bond is one of the strongest covalent bonds known
b) the thermodynamics do not work out
c) the H in H2O is already fully oxidized (by the "common" definition of oxidization noted above)
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by:rrhunt28
ID: 8246656
To make water "burn" you can use it in chemcial reactions that result in fire.  Like putting in sodium, potasium, things of that nature.  However I would not try this at home, because the reaction is quite violent.
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by:waffleironhead
ID: 8246993
water does burn...found out myself when i was a tyke making jello....grrrr....boy did that blister hurt

waffle
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by:MusicMan
ID: 8247068
After my silly post earlier on, I actually have something serious to offer on the same lines.  I have been racking my brains all day trying to think of a liquid that will burn unaided and have not been able to.

Petrol does not burn as a liquid, it is the vapour that burns, same as methylated spirits etc.

Oil needs and ignitor, and will only burn unaided when it has been heated to such a temperature as it is then vapourising.

Candle wax needs the wick to burn.

I have no doubt that those of you with chemistry backgrounds will now make me look totally stupid, but I can't think of anything that will burn in liquid form.

MM
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by:SunBow
ID: 8248203
> but I can't think of anything that will burn in liquid form.

Catalyst can be useful. (After a quick google I found sites that supplied photo proof of experiments. Some claimed maovies available but links were broke so I won't post)

Water burns. Catalyst Sodium. In large open parking lot, drop the sodium catalyst into a large bucket of plain water. One site filmed tossing it into a puddle of water. Better stand back, flames are enormous. And hot. When the water burns, its H2 is freed, as gas... and also hanging out where it is both very hot and a flame is ongoing, so it ignites as well (in a controlled situation, elimination of flame can lead to hydrogen collection), joining with airborn O2. Example of Recombinant chemistry. So you get two very hot things burning hotter than ever.

(ok, theory is that it's the solid sodium that burns, not the liquid water, because it is wet. I think there's liquids that burn, but cannot think of one either. what about space age rocket fuels, combining two liquids? No O2 in space for burning.) Also note than ability to burn also has dependencies on pressure, temperature, etc. and usually... needs flame and at times a catalyst other than yourself.

Lithium has similar behavior to sodium as well. Ever notice what happens to the over-active people who are given their doses of lithium to stabilize?  They sure behave like their brains were fried, burning them out. (note: most of your body is mass of water)

Back to the point of it all,,,

>Jerry_Pang  03/31/2003 05:40PM PST  
> how do make hydrogen burn?

Add O2, heat, ignition (flame)
see also: Hindenburg

> To make hydrogen fuels, they extract hydrogen from h20. WHy? whats wrong with h20?  

I need this rephrased. Several answers already given, primarily the (roughly speaking) 2H2 + O2 = 2H2O or rather, 2H(OH), meaning that it is the result of the combustion you seek. Or, accept my sodium analogy.
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by:SunBow
ID: 8248384
That Lithium trip reminded me of the havings of DTs (withdrawal?). Substituting extracts from:
http://library.thinkquest.org/17940/texts/fusion_dt/fusion_dt.html

Deuterium-Tritium (D-T) Reaction

.. fusion of two hydrogen isotopes: deuterium (2H) and tritium (3H). It is the easiest fusion reaction to achieve on Earth, and will most likely be the type of reaction found in first generation fusion reactors. The actual reaction involves a deutrerium nucleus fusing with a tritium nucleus to form an alpha particle (4He nucleus) and a neutron. The products contain around 17.6 million electron volts (MeV) of released kinetic energy through the loss of mass in the fusion process.
...
Deuterium can be found on Earth, although in a very small quantity (.015% of natural hydrogen is deuterium).
...
One gallon of sea water has the energy content of 300 gallons of gasoline
...
6Li + n => 4He + T
The lithium absorbs the neutron and generates a tritium while releasing a bit more energy in the process. There is plenty of lithium available in nature.
...
7Li + n => 4He + T + n
...
other reactions besides the D-T that would work, incuding D+D, T+T, and D+3He reactions. The D+3He reaction in particular is a promising reaction, in that this reaction is the easiest "aneutronic" reaction, producing 4He and a proton 4He + T
The lithium absorbs the neutron and generates a tritium while releasing a bit more energy in the process. There is plenty of lithium available in nature.
...
---------------------------------------------
Thus for a question:
> Does water burn?

Answer is: YES

Even plentiful salt water has abundance of natural deuterium. Although small in number proportionately, concentrating what is available in a small bucket of water can heat you up real good, including the effects from resulting radioactivity. Thank goodness the existing stuff is dispersed well, huh? Just think of it, some goofball scientist hack may test out some theory and ignite the world's oceans. So much for leaving a legacy in search of fame. Shades of the original atomic test blast, where many took bets that they'd ignite the (O2) global atmosphere, others simply incinerating the state or even the American West. (Scientists came from the East). Similar but opposite (antonym?) to Ice-9, freezing all the oceans.
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by:Itatsumaki
ID: 8248440
SunBow and others,

When you add solid sodium to water, is the water really "burning"?  Nothing gets further oxidized.  The production of hydrogen peroxide is a further *reduction* of the oxygen.  That's not the most stable thing in the world, and can easily dissociate into H2 + O2.  Why?  Well, forgetting bond energies for a second, think of the entropy -- one mole of liquid ==> two moles of gas.  The rapid expansion is accompanied by a large amount of heat release, sure.  But this isn't really something burning, it's just a rapid release of hot gases.

So, if you want to define "burning" as "the release of damnably hot gases really quickly" then there are tons of ways of making water "burn".  You could do it electrolytically (you'd need large electrodes, of course), or with simple temperature.  Reducing the pressure so that the vapour pressure increased sufficiently, then flashing the temperature could do a wonderful job here.

I just don't think this is really "burning" in the same sense as paper or oil burns.

On the other hand, we've probably talked this topic to death anyways. :)
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by:Itatsumaki
ID: 8248460
Achs SB, that's a nuclear reaction.  Very distant from "burning" in my mind.  Jerry didn't ask "does water undergo exothermic reactions", he asked "does it burn"?

Two very different ideas.
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by:SunBow
ID: 8248629
This dude is very readable, commonsense, I highly recommend. I used to read stuff in local newspaper before it got bought up. Some enthusiasts I know visit his website regular. (my providing a link is not meaning recommending, just an fyi unless I state otherwise).

http://www.straightdope.com/classics/a970905.html
A Straight Dope Classic from Cecil's storehouse of human knowledge

Dear Cecil:

Why doesn't water burn? It's made of hydrogen, which is flammable, and oxygen, a necessary component of flame. Yet every time I put this question to someone who knows about chemistry their eyes roll back in their head and they nearly pass out, and when they come to they give some explanation that is so complicated and incomprehensible I have to lock them in the trunk and drive them around town for a while to make them shut up. I'm appealing to your brilliance to help me live a more settled life. --Sean Cearley, via the Internet

Cecil replies:

Sean, this kind of behavior is just not nice. At least it never works for me. Besides, there's an easy answer to your question. Water doesn't burn because it's already burnt.

Oh, sure, it doesn't look burnt. Nonetheless, it's one of the chief products of combustion. Light a candle, gas jet, whatever, and what do you get? Mainly carbon dioxide and water. We started off with a hydrocarbon and the hydrogen oxidized. The result is water, a substance far more stable and thus less flammable than an unburnt mixture of hydrogen and oxygen.

Still, if you try hard enough you can get even water to burn. Try torching the stuff in the presence of fluorine gas. You get a nice hot flame that produces oxygen and hydrogen fluoride, which are more stable than water plus fluorine. That's about as simple as I can make it, pal. Hope it brings you inner peace.

--CECIL ADAMS

[Comment on this answer]
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SunBow earned 200 total points
ID: 8248871
Itatsumaki,
> When you add solid sodium to water, is the water really "burning"?  Nothing gets further oxidized.

If you missed it, I thought I answered both (post: after-the-fact)
No, the water wasn't burning, the science supposes it is the Sodium that is burning, but it grabs its oxygen atoms from the water! (so the water is involved in the burning process, releasing the free H2 into atmosphere).

And there is also the standard oxidixation going on. Not only is the sodium being oxidized, but also the freed H2 does not stay free so long, for it quickly combines with atmospheric O2 => burning hotly, producing water vapor, steam, as end product as well (the end is as in the beginning?). "Dust to dust", "ashes to ashes", water to water".

>  Very distant from "burning" in my mind.  

In my mind too. I don't think of paper, I think of flame. (btw: anyone know of cigarette lighter? In contains fluid, does not burn until the spark added. But is it the liquid itself burning? What is seen is liquid inside, gas outside). For me it is the flaming light wave provider.

But take the common city pedestrian. The heat of reaction will make one feel like they are burning, and the free neutrons accumulating in neghborhood including concrete will produce enough radioactivity to make one feel they are burning (should they survive). As to whether the person's skin itself ignites (flame) or melts, I'll leave that for another. That did happen on the Hindenburg, but that's another story. People head to beach and get burned by sun, without a visible flame, ignition, or catalyst.

> he asked "does it burn"? Two very different ideas.

Actually, a better refutation of my DT offering, would be that I referred to water, even salt water, where the questioner seems to take a straight line to H2O, and there I'd agree it just ain't the same. But in real world, one doesn't find much of anything being 100% pure. Like your reference to the peroxide, and then there's the everpresence of ozone.

>  other hand, we've probably talked this topic to death anyways. :)

I tend to agree concerning original question, but sometimes the diversions can be interesting as well. Such as, does a liquid burn, and I'd also forgotten about peroxides (don't they burn up germs?).
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by:MusicMan
ID: 8249504
According to this website :
http://www.osha-slc.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9752
A flammable liquid is one that has a flashpoint below 100 degrees centigrade.
If it has a flashpoint above 100 degrees centigrade then it is classed as combustible.
Therefore water is not flammable, because its flashpoint is higher than 100 degrees C.

And since the flashpoint of a liquid is the temperature at which the liquid vapourises, then my point of liquids not being able to burn is correct, as they must first turn into gas.

I still you lot are way cleverer than me though 'cos I couldn't understand any of that chemistry stuff.

MM
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by:Itatsumaki
ID: 8249570
Hey Sunbow,

Sorry, missed your points about the Na.  I see what you are thinking, but I still very much disagree that this is combustion!

Let me take a better stab at describing what I think the common idea of "burning" is.

1. It is an *interface* event.  That is, an explosion is NOT a fire.
2. It is a chemical reaction -- not nuclear, not enzymatic
3. One of the two phases at the interface must be atmospheric gas
4. The substance that is burned is oxidized by the atmospheric gas.

By this definition water simply does not burn.

If you reduce the requirement of point 4) to allow non-atmospheric gas to be the oxidizing agent, then water can be reduced by, amongst other things, several fluorinated compounds.

As to the idea of "sun burn", I think that refers to neurological and dermatological phenomenon rather than to any chemical idea of "burning".  I think most people differentiate that from standard flames.

Now, the idea that "liquids do not burn" is a bit troubling.  Oil burns, does it not?  All heavier hydrocarbons burn.  Alcohols burns.  Sure, things burn easier when they have a higher vapour pressure (i.e. lower pressure) but that doesn't mean oil doesn't burn at higher pressures.  It surely does, and one could calculate the ignition temperature for that, too.  A lighter is the same way: the high vapour pressure of the liquid (butane, I think?  Not sure) allows it catch fire easily.  Nevertheless, butane burns without that high vapour pressure.

In other words, the partitioning of the butane between the liquid and atmospheric phases (the thermodynamical partition constants) are not what determines if it burns or not.

Finally, you asked about peroxides.  Good question!!  I think they burn -- just thinking of the structure I'd be very surprised if they didn't.  I don't think they destroy bacteria that way, though.  I would guess that they react with various membrane components to generate reactive oxygen species that destroy the cell wall, membrane proteins, and any locomotive devices (e.g. flagella).  Just guessing on that, though.  I'd be curious if anyone knows for sure?
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by:rrhunt28
ID: 8250068
I have seen a small amount of pure potasium put into water, and it had flame....
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by:Jerry_Pang
ID: 8250133
listining...

probable winner - CECIL ADAMS(sunbow).
we are on the same boat MusicMan, couldn't understand any of that chemistry stuff.

anyway, still listening... im still trying to understand your chemistry-stuff answers.
 
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by:Jerry_Pang
ID: 8250159
"I have seen a small amount of pure potasium put into water, and it had flame...." ?? really? should try this one. Hmmmp.. now where could i find a potsssium? (the only think i could think of is banana. )
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by:rrhunt28
ID: 8254528
LOL, no pure as in used for chemistry.  And I would not try it unless you know what you are doing.  It was a piece about the size of a half a pea, and it was pretty violent.  If you had a large chunk, it would be like a bomb.  And other elements are more reactive.
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LVL 17
ID: 8254630
I remember from chemistry the instruction "Always add the metal to the water, not the water to the metal"
Apparently the reaction was less violent this way, although one chemistry teacher suffered serious burns and nearly lost an eye whilst demonstrating this experiment.
They used potassium, sodium and lithium which were stored in little jars full of oil.
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by:rrhunt28
ID: 8254659
Yes, they are full of oil to keep the moisture in the air from reacting.  Can you imagin a sealed glass jar getting alittle water in it, talk about your granades....

And in other unrelated news, you always add acid to water...
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by:andyalder
ID: 8255129
We used to drop lumps into the drain outside the headmasters office :)

Has anyone debunked my liquid water burning in an atmosphere of sodium gas yet? I think it can produce a flame with the water drop being below 100C. I was going to do the experiment last night but the police told me to come down from the lamppost ;-)
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by:The--Captain
ID: 8259398
Water will burn under any conditions that cause it to react in the presence of another agent (or itself) with appropriate vigor (the "with appropriate vigor" clause is to satisfy those who think slower reactions do not constitute "burning").

As such, I would recommend accepting the initial comment - you can't burn a water with a match because the match isn't putting out enough energy to seperate the H20 molecule.  On the other hand, it's pretty easy to burn water with an H-bomb, no matter what your environment.  Cecel Adams summarized it nicely, although with a bit of tendancy towards the silly (as is his nature).

Cheers,
-Jon
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ID: 8259449
>I remember from chemistry

Correction 'I thought I remembered from chemistry'

rrhunt28,
Thanks, it was nearly the same sentence but acid not metal.

Bits of my memory are failing, I wonder what else I have lost.

Teacher's injuries are definite though, performing the exp. on his desk behind a glass screen to protect onlookers, there was no screen between him and the bang.
One of those 'Cor! Put a big bit in Sir' moments.

Same man used to knock up a magic powder for theatricals and never told us what was in it, squirted with water (I think) it used to provide a bright flash and lots of smoke so the old crone could change into the magic fairy, or the King Rat could appear. Does anyone know what this powder might have been?, phosphorus, magnesium?
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by:rrhunt28
ID: 8261771
Not sure...

I have heard of something called greek fire.  It is a liquid that when thrown into water creates fire.
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ID: 8261882
from Britannica:

Greek fire,
any of several flammable compositions that were used in warfare in ancient and medieval times. More specifically the term refers to a mixture introduced by the Byzantine Greeks in the 7th century AD. The employment of incendiary materials in war is of ancient origin; many writers of antiquity refer to flaming arrows, firepots, and such substances as pitch, naphtha, sulfur, and charcoal. But true Greek fire was evidently a petroleum-based mixture. It was invented during the reign of Constantine IV Pogonatus by a Greek-speaking Syrian refugee from the Arab conquest of Syria. It could be thrown in pots or discharged from tubes. The substance apparently took fire spontaneously and could not be extinguished with water.  
Greek fire launched from tubes mounted on the prows of Greek ships wrought havoc on the Arab fleet attacking Constantinople in 673. Greek fire was later employed effectively by Leo III the Isaurian against an Arab attack in 717 and by Romanus I Lecapenus against a Russian fleet in the 10th century. Its deadliness in combat, especially at sea, has been cited as a prime reason for the long survival of the Byzantine Empire in the face of many enemies. The art of compounding the mixture was a secret so closely guarded that its precise composition remains unknown to this day


I don't think this would have been it.
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by:rrhunt28
ID: 8261980
Interesting.   Maybe it is a myth that it caught fire on water, maybe it simply would remain on fire on water.  Like an oil spill.
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by:SunBow
ID: 8262686
Water is a "not flammable" proof by experimentation. Take one long stick match, and light it. Make detailed observations as you gradually dunk it in a bucket of water. Hear the sizzle? That's the sound of the water molecules ferociously swimming forth and attacking the flame. More zealous and quicker results than a pack of pirhana. Thus it is said:

Water is inflammable                     ; a flame killer.
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by:rrhunt28
ID: 8262730
LOL, the sizzle is the sound of the water absorbing energy to change states.
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by:Itatsumaki
ID: 8271517
~sighs~

I stand by my initial statement that "flame" requires oxidation by the atmosphere.  Since the atmospheric oxidizer is O2, and you can't add more O2 stably to water, it won't burn.

Those other things suggested -- fluorination, for instance, or working in an Na atmosphere -- are not flame according to what the average person thinks of as "fire".

So, in my mind: no additional oxygenation = no flammability.
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by:rrhunt28
ID: 8271633
Well, I agree with you to a point.  However you have to define(as you did) how you treat the word flamable.  
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by:SunBow
ID: 8292689
Thanx.                                                           -[Good Fortune]-
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by:Zlatin Zlatev
ID: 10262683
Answer 1:
Give me food and I will live; give me water and I will die.
What am I?

:)
Answer 2:
Water is the "ash" of hydrogenium. Have you ever burned ashes without adding someting inflameable?

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by:Zlatin Zlatev
ID: 10262719
I know it is closed - just to show my point of view :)
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by:SunBow
ID: 10282876
POV always welcome.
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