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why does water not burn?!?

This discussion thread has 26 messages.

#1
well the subject explains its self realy, but water is made of 2 hydrogens and 1 oxygen, hydrogen burns and oxygen helps things burn so why does it not burn. i asked my cousin this (he thinks he knows everything but i just think that he is a big tall idiot with his head in the clouds) and he said it was the bondings on the atoms, but it is just a strait chain molicule and therefor has not double bonds to make it harder to burn, and also the molicule is very light and small so that means it should burn easier. can any1 tell me or even suggest an idea of why it does nor burn, please.

thanking the smarty pants who gets the right answer in advance.

!!thecraigc!!


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#2
burning is just the process of matter changing from one form to another. it causes bonds to be broken and reformed to create new materials. water doesn't burn because it doesn't change form that way. water's bonds must be broken in other fashions.


#3
you like linkin park? wow, they have to be one of the worst bands ever...

"I have no particular talent. I am merely inquisitive" - Albert Einstein

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#4
How about the fact that if water didn't expand when frozen we would not be here on earth today...
#5
aabbccdd Suspended account
does hot water or cold water frezze faster? (iknow)

and what is the temp. of a glass of ice water? (with the glass completely full of ice}
#6
did you know that you can make water "wetter"???

and did you also know that wood dosnt burn??



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#7
oh btw,about water not burning,you need heat to create fire along with oxygen and fuel



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#8
so why does hot water not burn?

We knew the world would not be the same. A few people laughed, a few people cried, most people were silent...

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#9
still a liquid but does burn skin.
#10
hot water freezes faster than cold water

something about it has the cold water moleucules being so close together already and the hot water being farther apart and when the start to calm down and get closer together the move to the freezing part faster


#11
i dont see that as being true.

before the water can begin to freeze it must first become cold water.
it can not go from hot to frozen without first becoming cold.

it must first take time to become cold, then this cold water will take the same ammount of time to freeze as the normal cold water would that was not warm to begin with.

therefore it will take longer to freeze hot water.
doh :)

We knew the world would not be the same. A few people laughed, a few people cried, most people were silent...

J. Robert Oppenheimer
#12
What Should Happen

Any reasonable person would think that the hot pail would take longer than the cold pail to freeze. After all, the hot water needs extra time to reach the same temperature as the cold pail. When the hot pail finally does reach the same temperature as the cold pail initially was, the cold pail should already be frozen.


What Actually Happens


There are several things that help the hot pail freeze faster than the cold pail. Here are what is thought to be the most significant factors:

Layer of ice forms on the top of the cold water.

The hot water is more likely to be supercooled. This means that the hot water's temperature is more likely to cool to temperatures below zero degrees Celsius. In the cold non-supercooled water, ice crystals form and float to the top, forming a sheet of ice over the top of the water, creating an insulating layer between the cooler air and the water. This ice sheet also stops evaporation. In the hot water that has become supercooled (thus, no longer hot) the water, when it does freeze, freezes throughout, creating more or less of a slush before freezing solid.

Why is hot water more likely to be supercooled? Because hot water is less likely to contain tiny gas bubbles. Gas bubbles form from dissolved gasses as the water cools. When the hot water was heated, these dissolved gasses may have been driven out. In cold water, ice crystals use the tiny bubbles as starting points for formation (in physics, we call them nucleation points). But in the hot water, there are no bubbles, so there aren't as many starting points for the ice crystals.

Dissolved gasses also lower the freezing point. Since heated gas is less likely to contain dissolved gasses, it's more likely to freeze first.


Water in the hot water pail evaporates at a much faster rate than the cold water. This does two things.

First, the process of evaporation is endothermic, which means it takes energy for something to evaporate. As a molecule of water evaporates, it leaves the surface of the water and flies into the atmosphere. Thus, in simplified terms, the molecule converted heat energy into kinetic energy (energy of motion). Since the hot water evaporates quicker than the cold water, it loses heat energy quicker than the cold energy.

Second, since some of the hot water evaporates away, there is less water left to have to freeze.

The hot water pail will melt the surrounding snow. Later, as it begins to freeze, the snow around the pail will freeze back so that it more closely "touches" the pail. The cold water pail is then only sitting in fluffy airy snow, while the hot water pail is in a form fitting ice-crust. The ice-crust will obviously conduct the cold better that the airy snow.

Other factors, such as convection currents (the movement made as hot water rises while cool water sinks) may or may not play a role in this odd phenomenon.


This message has been edited since its posting. Latest edit was made on 04 Jul 2005 @ 4:16
#13
even wirh gasoline the liquid itself does not burn its the vapor off of the liquid that burns

well u say how come when u throw a match in a bucket of gasoline it ignites if u look closely enough its only the top burning witch is the vapor now gas does has a boiling point so when the entire container becomes so hot the liquid becomes vapor very quickly and that when u get the big flash

something fun to try is to dissolve like 5 or 6 big pieces of styrofoam into a cup of gasoline and u get a form of homemade napalm fun fun fun


#14
aabbccdd Suspended account
Yes hot water does freeze faster than cold water

and the temp. of a glass of ice water will be 32 degrees
#15
So does anyone have the answer to why we would not be here today if water didn't expand when frozen, something not common with liquids?
This message has been edited since its posting. Latest edit was made on 04 Jul 2005 @ 12:13
#16
Geeze too scientific for me.

Water will never burn because it is wet!!!!!!!!!, Einstein told me that in a dream, so it has to be right..................




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#17
simple answer, but might just b the correct 1, LOL

!!thecraigc!!


#18
I FOUND THE ANSWER

you get a big chunck of ice and lots of thermite, i think thats what it's called anyway, its a mixture of iron oxide (rust) and aluminum, you put a bucket of the thermite stuff on a block of ice, put a pot over that, run a fuse from the thermite to a good distance away then light it, it burns so hot that it splits the molicules of water apart, like the cracking process used in oil, then the hydrogen and oxygen atoms burn together making a big, big fire. i seen theis on brainiac.

heres a link to instructions if you want to do it your self -- http://www.skyone.co.uk/SKYONEFORUM/ShowPost.aspx?PostID=81521

i can't find a clip of this anywhere, if i can i'll post the link

!!thecraigc!!


#19
xboxdevil Suspended account
i agree with that scubabud guy.water doesnt burn it evaporates turning into steam which in itself is a chemical change it changes from liquid to a gas and if you cover the steam it will turn back into water. that is my explaination in laymens turn.

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#20
Combustion is the process of reacting a substance with Oxygen gas. Water is formed by the complete combustion of hydrogen gas in the presence of oxygen. Thus it is already combusted, and cannot be reacted further with oxygen. It is like this with many things, e.g. carbon dioxide is formed by the combustion of carbon or organic compounds - e.g. ethanol which contains carbon, and everyone knows CO2 does not combust, why do you think it is used in fire extinguishers. Note, there is also the compound H2O2 - hydrogen peroxide, but we wont get into that as it doesn't have much to do with combustion and water.

Also, in response to other points:
Water is not a straight chain molecule, it is bent.

Water has a relatively small molar mass, and this is not proportional to how well something burns. Petrol has a much higher molar mass than ethanol, but releases much much more energy when burnt. It has more to do with the bonds within the molecules.

Hydrogen is very reactive, as is 0xygen. In simple turns, they are reactive because hydrogen wants to lose one electron, and oxygen wants to gain two, so that they can become stable. Thus two hydrogens will bond with one oxygen, and they will share electrons to become stable!

Water also becomes even more stable due to hydrogen bonding. In lamens terms, it is when the hydrogens on the water molecule are attracted to the oxygen atoms of seperate molecules, and they move togethor by a force of attraction, which raises the boiling point and melting point of water.

Oh and thermite, it is used for underwater welding because it burns at and incredibly high temperature. Putting that much heat into water will break the bonds within the molecules, and will break the bonds in many other things. It will go straight through most metal, and usually has to be stopped by a bucket of sand, where it turns a big lump of it to glass.

The process of liquid water turning to steam is a physical change, not a chemical one. It is still H2O but it has more energy and the molecules move faster and more freely, in other words it is less dense, hot water.
#21
ok..... has anyone touched on Dry Ice? And water can burn....

ok...... foood for thought...... just watched Discovery Channel about metors..... When the metor that caused the Ice Age fell into the ocean it caused the water to Vapor and scroch the earth...... in a matter of months the whole earth burned and then Caused the Ice Age...... where everthing just froze! Weird, huh? Well......... water can burn!! Soooooo says the DISCOVERY CHANNEL! ahhahahahhaa
#22
I dont see how you got that water can burn from that information?? Being vaporised is not burning, if thats what you mean. Dry ice is soldid carbon dioxide and it sublimes.
#23
You are correct. Sublimation is not the same as burning.
This message has been edited since its posting. Latest edit was made on 14 Oct 2005 @ 19:11

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#24
Deadlywave is correct, and once and for all water can not burn.
Ihoe, the water did not burn. It may have burnt the earth with the heat of vapourisation but the water its self did not burn it just turned to steam.

;)

We knew the world would not be the same. A few people laughed, a few people cried, most people were silent...

J. Robert Oppenheimer
#25
The burning already took place when the two hydrogen atoms combined with an oxygen atom. When the water molecule was formed, energy was released. The H2O molecule is stable and now requires an energy input to separate the water molecule into its component parts.
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