Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: neilep on 25/03/2007 23:19:47
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Dearest Luvvys,
I have heard that in some cases water can in fact make a fire worse....in fact it can even be fuel for it ..how come...?
Dowse me with the dilution of your viscous answers
Ta
neil
xxx
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Grease and chemical fires can be made worse by throwing water at them. My sister had a grease fire and turns the water on from her sink sprayer and it spread the grease up the wall and right into the cupboards where the grease was splattering and being spread.Like gasoline it separates from the water and remains combustible only spreading in distance and surface area causing a bigger fire! I am sure there are other chemicals that do that also. THat is why it is so important to have a abc fire extinguisher in your kichen. If you do not you should throw baking soda on it to stop the spread. Grease fires are horrible to contain if you are not careful! That particular Fire extinguisher will put out both kinds of fires safely and effectively.
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Sir Neileot Hiya. :)
Ive never heard that one.
Water I believe can help spread help a fire i believe if used on something like petrol but i believe thats because it spreads the fuel over a larger area. (COULD BE WRONG)
If introduced to a fat pan fire it can cause it to sort of explode ,which i believe is due to the water rapidly turning to steam (COULD BE WRONG)
but i dont think water can be considered a fuel for fire.(THIRD TIME LUCKY :)
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Water does help spread grease fires because as soon as it comes in contact with the boiling grease, it starts to boil violently (think of what happens when water gets into hot oil when you're frying something). This causes spattering of the grease at least, and an explosion if its violent enough.
Water is also a bad idea when it comes to electrical fires.
In general, water is only good for putting out wood and paper (class A) fires, which is why few fire extinguishers actually use water.
In general, water doesn't actually act as a fuel, but it can act as the oxidant for metal fires. Magnesium, for example, is one of those things that REALLY wants to react with oxygen, whether it's bound up in another molecule or not. If magnesium doesn't have elemental oxygen available, it will get it from whatever molecule happens to be around. This could be water (it will burn under water) or carbon dioxide (I've seen magnesium burn while sandwiched between two slabs of dry ice.
In rare cases, water can act as a fuel (i.e., reducing agent), but only in the presence of an extremely strong oxidizer, such as fluorine.
Dr. Dick
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THANK YOU Karen & THANK YOU Sir Michaelot ! (wocha !)
I am aware that water in the case you've mentioned makes it worse by being the wrong thing to use to extinguish those fires....but in what I heard it was that water then became a fuel....not an agitator !...it actually combusts....
I could be wrong....(ten mins later)........I'm pondering !!...I think there might have to be something specific about the fire in question........temperature ?....yes..yes...what about temperature ?...what about an unusually hot fire ?
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DrDick....THANK YOU very much Sir.....I think you got it there when you said that magnesium burns underwater !!...This is what I think I heard (or words alike)....a component of the water , (in this case oxygen yes ?) is actually the fuel for the fire.
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Very interesting! The details are ..well nice..!
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...a component of the water ... is actually the fuel for the fire.
Actually, magnesium is the fuel, whether it's in air or in water.
Remember that for a fire to occur (and be sustained), you need three things: fuel, oxidant and heat. Here, the magnesium is the fuel while oxygen (in air) or water (or CO2, etc.) would be the oxidant.
Dr. Dick
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I stand corrected and am pleased to be so..THANK YOU DrDick.