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by iasksimplequests on September 26th, 2006

iasksimplequests

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Why does water extinguish fire? Especially since water is made of H (hydrogen) and O (oxygen), the two gases which helps a fire burn.

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Answers. 17 helpful answers below.

  • by milkhoney on September 5th, 2008

    milkhoney

    The same reason that salt tastes good, but you would really regret stuffing sodium or chlorine into your mouth. The stable joining of two elements into a molecule changes the properties of matter.

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  • by Glenn Blaylock on July 16th, 2008

    Glenn Blaylock

    There are a couple of things involved here. First of all, as another person noted, when hydrogen burns (combines with oxygen), energy is released. The water molecule exists in a lower energy state than elemental oxygen and hydrogen do. So the water molecule is more stable than the elements which it is made are separately. Water is the "ash" of burning hydrogen. So, it won't burn anymore than the ash of a wood fire will.

    Second, fire need three things in order burn. It needs a fuel, an oxidizer, and heat. The fuel is that which is combined with the oxidizer to release energy. The oxidizer is in most cases is oxygen, but there are others as well. The heat is needed to break apart the molecules in the fuel and oxidizer so that the components will combine into new compounds thus releasing more energy to keep the reaction going. If any one of these three things is missing, then you will not have a fire.

    Water puts out fires by disrupting all three of these requirements. When water in smaller quantities is put on a fire it absorbs heat that is needed to initiate combustion. So, it can stop the reaction by removing too much heat. In larger quantities water can separate the fuel from the oxidizer (air) thus also preventing them from combining. This smothers the fire.

    Finally, I will also point out that all compounds produced by burning can potentially put out fires. The reason is because these products have already combined so there is no more energy to be derived from them in this way. So, placing them on a fire will tend to interfere in the processes needed to keep the fire going. They would mostly work by smothering the fire if used in sufficient quantities. (Water is the only one of these combustion products that I know of that is also able to put out a fire by sapping heat.)

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  • by Rince on September 5th, 2008

    Rince

    Hmmmmm.... I can see we are going to have trouble with you :-p Welcome to Answer Bag :-)

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  • by jcmil2 on December 22nd, 2008

    jcmil2

    Fire is composed of four elements: heat, fuel, oxygen and a chemical reaction. Water removes heat from the equation. Dry chemical removes the oxygen. Foam removes both heat and oxygen.

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  • by Quirkie on September 28th, 2006

    Quirkie

    When things burn, combining with oxygen, energy is released. You would have to put in yet more energy than this to split away the oxygen again. So the burnt items stay burnt - including the water which is burnt hydrogen.
    Water extinguishes a fire in two ways: by boiling - which takes a lot of energy from the fire, and by smothering.

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  • by xprofessor on July 16th, 2008

    xprofessor

    When atoms re-arrange themselves into molecules by forming chemical bonds, the whole energy balance is totally changed. Hydrogen is flammable and oxygen is an oxidizer that supports combustion. The two gases combine explosively to form water, releasing a great deal of energy. Water, once formed, has very little chemical energy locked into its bonds. But because it's a non-flammable liquid with a good heat capacity, it extinguishes fires.

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  • by Cyanotic Wasp on September 5th, 2008

    Cyanotic Wasp

    Well, technically, oxygen doesn't 'burn'. What we call burning is the process of oxygen combining with other substances in a process that is technically known as "oxydizing". (Rust is a 'slow burn' of iron, as it oxydizes over a longer time. The flame that you get from a struck match, candle or cigarette lighter is the fuel oxydizing more quickly.)

    When hydrogen oxydizes it combines with oxygen molecules, and the resulting product of combustion is water vapor. So in a way you could say -- in a sense -- that water is the "ash" left over from that reaction.

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  • by bowlermommy07 on September 5th, 2008

    bowlermommy07

    Something to do with the electrons and the energy levels. I'm not really sure how to explain.

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  • by Anonymous on September 26th, 2006

    Anonymous

    Water(H20), will extinguish most non-electrical fires, by depleting the oxygen needed to fuel a non-electrical fire.

    Water cannot be used on electrical fires as the electricity will follow the water and hose to the firefighter and cause an eletrocution. water is also not successful in fuel fires. water can never be used on aircraft wheels made of magnesium. this will cause an explosion. lite water or chemical foam is used.

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  • by Anonymous on June 26th, 2008

    Anonymous

    For oxidation to take place there should be a particular temperature.When water poured into fire it absorbs most of the temperature.So the temperature will not be sufficient to maintain oxidation.

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  • by Bobby Dias on September 26th, 2006

    Bobby Dias

    One way is that the force of the water spreads little bits of flame away from the fuel.
    Another way is that the water can prevent the fire from using the available air BEFORE the air in the water is heated to the point that the water separates from the hydogen(when the oxygen is combustible)- by smothering the fire.

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  • by Witz_N_Charm on September 26th, 2006

    Witz_N_Charm

    Water will not always extinguish a fire.
    IT depends on WHAT type of fuel the fire has.
    grease, wood, electrical, ect.
    as for why, that i dont know

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  • by john pennington on June 26th, 2008

    john pennington

    Water, smothers oxygen, thus extinguishing the fire.

    The same would apply, if you have a fire in a basket, for example, and you used a blanket instead of water to smother the flames.

    Its all about cutting off the oxygen supply to a fire.

    Caution: never use water to extinguish an electrical fire. you will be electrocuted.

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  • by Big Guy on September 5th, 2008

    Big Guy

    Well actually if its hot enough water it will burn.

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  • by will on June 18th, 2009

    will

    glen blaylock was pretty close. His explanation on the H and O molecules is sound.

    As far as three things needed to extinguish a fire - he incorrect. Fire needs four things to burn, not three. The "fire tetrahedron" says you need fuel, oxidizer(oxygen), heat, and self sustaining chemical reaction.

    If you remove any of those four things the fire will be extinguished.

    Water works in a couple of ways. But remember, water will not put out all fires! It can intensify or spread some types of fires! Example: Magnesium. There is a chemical reaction when water is applied to a magnesium fire. The reaction provides pure oxygen to really stoke up the fire! It is a sight to see.

    It absorbs heat. enough can create a barrier between the fuel and oxidizing agent, in its gaseous form(steam) it can displace the oxygen. In every case, one element from the fire tetrahedron is removed - heat, oxygen, fuel, chemical reaction.

    Have you ever seen fireman use those streams that are tightly compact? they are known as straight streams from a smoothe bore nozzle. How about the use of a cone type spray? This is from a fog nozzle.

    The smoothe bore nozzle sprays basically a tight stream of water. It does not absorb alot of heat. It is primarily used for distance, breaking through a window, and cooling/smothering the fuel itself.

    Fog nozzles break the water into smaller droplets. The smaller the droplet, the more heat it absorbs. Take a large ice cube and put it in a glass of water. at the same time, break up another cube into alot of pieces and put it in another glass. The small peices provide more surface area than the large cube resulting in greater heat absorption.

    So, a fog nozzle absorb much more heat. A means of extinguishing a fire with little water is to use extremely small droplets with a fog nozzle and attack the fire. Water expands 1,700 times it's original volume when it converts from its liquid to gaseous state. think about it - 1 cubic foot of water = 1,700 cubic feet of steam! So when you spray 100G of water on a fire it generates alot of steam(which is bad for firefighters). Alot of heat is absorbed when this water is converted to steam. The steam itself actually displaces the oxygen in the room.

    to learn more look up "fire streams", "fire science" or anything related to fire fighting.

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  • by roger on December 22nd, 2008

    roger

    Is there a temperature limit above which water actually feeds the fire?

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  • by ItisANDitisnt on April 14th, 2012

    ItisANDitisnt

    Evaporating water creates water vapor, not hydrogen.

    Most of the energy in a fire is lost when water that gets put on the fire changes phase from a liquid to a gas.

    The water vapor that then gets left further cools down the fire until it gets extinguished.

    keep in mind that not all fires should be extinguished with water, some fires get extremely dangerous with the application of water.

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More Questions. Additional questions in this category.

You're reading Why does water extinguish fire? Especially since water is made of H (hydrogen) and O (oxygen), the two gases which helps a fire burn. - which can also be phrased in the following ways:

  • Why do two flamable gasses (hydrogen and oxygen) make a compound that exstinguishes fire?
  • If hydrogen burns and oxygen burns, why doesn't water burn?

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