Why Is Water Not Combustible and why does it put out Fires ?

Question

I understand that water consists of molecules of Hydrogen and Oxygen. Both of these are flammable gases, yes ? Why then doesn't water burn if we apply fire to it ?

Secondly, why does this compound called water put out fires rather than increase their intensity ?

Answer 1

Water will not burn because it has already been burnt once. When hydrogen burns it reacts with oxygen and once it is fully oxidised it cannot burn any further.

Water puts out fires by at least two mechanisms. Water has a high specific heat capacity (i.e. it takes a lot of energy to heat it up - this is why spou cools faster in a thermos flask than tea or coffee) and it also requires extra energy to vapouise into steam. So when water is put on a fire it is heated up and/or turned into steam. This effectively removes heat from the fire which will eventually lower its temperature below the point were it can continue to burn. One of the requirements of a fire is that it has a sufficiently high temperature to ignite. A second requirement of a fire is that it has a supply of oxygen and water can also help to reduce the oxygen supply by a smothering action as well as reducing the local partial pressure of oxygen by the production of steam. For these reasons, water is most effective when sprayed into the heart of a fire - a jet at the top of a fire won't be as effective.

In certain circunstances, water CAN increase the intensity of a fire so you need to be aware of what is burning before attempting to use water to extinguish it. Examples are oil fires, the water may produce an explosion of steam that causes the oil to spread and burn even more vigourously, some chemical fires, the water may react with the chemical causing more fire or an explosion, and water should never be used on electrical fires.

Answer 2

water will not burn because there is a strong covalent bond between the oxygen and hydrogen molecules, which cannot be broken by the temperature of the fire. Therefore the water is not combustable

water does simply put out fires because it stops oxygen getting to the fire and lowers the temperature

Answer 3

a compound is one which differs from the chemical properties of its constituent atoms or molecules.even so oxygen is just a supporter of combustion it is not a fuel like H2.
water when put on fires prevents the contact of fire with the air which is essential as air contains O2 and H2,CH4 etc.

there are some essential properties for combustion to take place:
1)Attainment of ignition temperature
2)presence of combustible substance
3)presence of supporter of combustion

what a fire extinguisher does is
1)reduces the temperature such that it goes below combustion temperature
2)prevents contact with the supporter of combustion

water satisfies both these conditions it forms water vapour at high temp. and forms an envelope preventing the contact with air

Answer 4

Water doesn't burn because it's actually ash. When you burn hydrogen gas it combines with oxygen. The result is an ash we call...water.
So water has already been there, done that.

Answer 5

a hearth demands 3 issues; gas, oxygen, and warmth. including oil to the hearth merely provides gas and subsequently it gets larger. Water places out hearth by making use of soaking up the ability (warmth) produced throughout the chemical reaction. If the water is utilized as a very thick mist over an oil hearth (no longer a vapor yet close) then the mist might soak up the ability and subsequently placed out the hearth. If it utilized as a stream of water then the water might merely stay with the aid of the flame and allow the oil to waft on the water subsequently no longer soaking up the ability.generating the mist is ineffecent and confusing to offer so oil fires are ussually extinguished by making use of removing of the oxygen (a foam applicate) or removing of the gas (baking soda absorbs the oil).

Answer 6

The hydrogen and oxygen are combined, they are not separate and in an explosive state. Hydrogen explodes. Oxygen is an oxidizer, it helps fire burn. Combined they take the heat component out of combustion, removing one of the three legs necessary for fire to continue.

Answer 7

because there is nothing flamable in water and water on fires lowers the tempature of the fire and the wate of the water helps knock out the oxygen feeding the fire.;

Answer 8

Simply because it cuts off oxygen and reduces the temperature.

Answer 9

fire needs o2 to live and by putting water on it it takes away the o2 it needs to live.