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Topic: Why doesn't water burn?  (Read 46051 times)

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Offline tortoise

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Re:Why doesn't water burn?
« Reply #15 on: May 13, 2005, 09:38:15 PM »
Can Axetylen (C2H4) burn water?

Garneck

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Re:Why doesn't water burn?
« Reply #16 on: May 14, 2005, 10:51:59 AM »
Can Axetylen (C2H4) burn water?

1. Acetylene is C2H2, not C2H4.
2. How do you imagine that acetylene can burn water? Acetylene can give a very high temperature of burning in pure oxygen, but that won't make water burn. Water can vapourise quicker, though.

Offline Donaldson Tan

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Re:Why doesn't water burn?
« Reply #17 on: May 14, 2005, 02:59:07 PM »
coverttolic's of burning water is effectively burning carbon. The carbon is somehow activated by water. energy is produced from the formation C=O bonds in the final combustion process. water is used to increase the reactivity of carbon, then it is regenerated in the combustion process. it isn't really burning water.
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Offline tortoise

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Re:Why doesn't water burn?
« Reply #18 on: May 15, 2005, 01:07:19 AM »
thank you very much

Offline sapta

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Re:Why doesn't water burn?
« Reply #19 on: May 15, 2005, 03:09:20 AM »
Qoute from Garneck
Quote
-"Water can vapourise quicker, though."

i think that just might be the answer(we need one dearly  ;D).water has a b.p. much lower than its burning point ???

Offline Borek

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Re:Why doesn't water burn?
« Reply #20 on: May 15, 2005, 04:33:50 AM »
Some of my friends suppose that water is the product of combustion (?) so water can't burn !?

In a way they are right - if you burn hydrogen in the oxygen you will get water.

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They say they has never seen any product of combustion which can burn

So they haven't seen all :)

If there is not enough oxygen carbon compounds burn only halfway to carbon monoxide which can later burn to carbon dioxide.
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Offline Borek

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Re:Why doesn't water burn?
« Reply #21 on: May 15, 2005, 04:36:02 AM »
I think that just might be the answer(we need one dearly  ;D).water has a b.p. much lower than its burning point ???

Whatever burning point is (is it ignition point?), I doubt water has one :)
« Last Edit: May 15, 2005, 04:39:22 AM by Borek »
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Offline jdurg

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Re:Why doesn't water burn?
« Reply #22 on: May 15, 2005, 01:58:59 PM »
At room temperature, it burns quite violently in an atmosphere of fluorine gas.   ;D
« Last Edit: May 15, 2005, 01:59:49 PM by jdurg »
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corey2

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Re:Why doesn't water burn?
« Reply #23 on: May 15, 2005, 04:58:29 PM »
Burning is by the common sense of the word, ignition of a combustible material in 20% O2 atmosphere
Well, water is already "burnt", it's hydrogen oxide, you can't really oxidize an oxide, unless using F2, as posted a lot of times above.

Offline tortoise

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Re:Why doesn't water burn?
« Reply #24 on: June 19, 2005, 11:55:45 PM »
So, does CO2 burn?

hannibal

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Re:Why doesn't water burn?
« Reply #25 on: June 20, 2005, 07:06:08 AM »
for any reaction to occur whether it is chemical or physical,the change in the gibbs free energy has to be negative this applies to "burning of water" too or "burning of carbon di oxide" too(by burning i mean a redox reaction with free oxgen molecule where oxygen act as a ).so oxidation of carbon di oxide with oxygen is possible at some suitable temperature, but i dont think this is possible for water as in water we have hydrogen which has no electrons to donate to oxygen atoms...where as in the case of carbon we still have some electrons in the inner 1s shell which can be taken out at some suitable temperature.....therefore combustion of carbondioxide is possible

Offline tortoise

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Re:Why doesn't water burn?
« Reply #26 on: June 26, 2005, 03:50:31 AM »
what does re-dox mean?

Offline xiankai

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Re:Why doesn't water burn?
« Reply #27 on: June 26, 2005, 05:35:43 AM »
red - ox refers to reduction and oxidation

in a redox reaction, a reactant is oxidised, and another reactant is reduced. products cannot be oxidised or reduced, unless they become the reactants of a subsequent reaction.

oxidation is the increase of oxidation number, while reduction refers to the reverse.

oxidation number is the charge of an atom or ion or cation or anion whichever seems best

take a look at http://en.wikipedia.org/wiki/Redox for further info
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Offline tortoise

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Re:Why doesn't water burn?
« Reply #28 on: June 27, 2005, 09:36:56 PM »
I recieved a question:

When we add some flourine gas to water, the reaction take places with 2 half-reactions:

F2 + H2O ----------> 2HF + O
F2 +  nO -----------> OnF2
 where n gainthe value from 1 to 8.

So where does the combustion process take place?

I really shock! I have never seen O2F2 or O3F2 ... I only see OF2.

Offline xiankai

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Re:Why doesn't water burn?
« Reply #29 on: June 28, 2005, 06:33:30 AM »
to combust something, u'll need an oxidiser and fuel. i'll think the 1st reaction sounds suitable because its redox and thus has an oxidising agent (not very sure about combustion and redox)

its possible obtain O2F2 or O3F2 in theory...

F-O-O-F and F-O-O-O-F

but there's got to be a catch.. either thermodynamic instability or something about those lines

« Last Edit: June 28, 2005, 06:39:57 AM by xiankai »
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