Water is made from hydrogen and oxygen, so why doesn't it burn?

Answer 1

Water is the more stable form of hydrogen and oxygen
so then it becomes something that can not burn

Answer 2

H2 and O2 react to make H2O. While both H2 and O2 are flammable, you are asking why is H20 not flammable also. There are actually several answers to this depending on what you are exactly asking.

One answer has to do with the fact that different structures have different chemical reactivities. So H2O does not have to have the same properties as its constituent elements.

Another answer has to do with the amount of energy that you add to the water. If you continuously add energy to water, you will eventually reach a phase where the intramolecular bonds of water (the ones that hold the water molecules together) start start breaking and water would decompose.

Hydrogen bonding is surely important in determining the temperature at which the molecule starts to break, but the intermolecular interactions are NOT the reason why water does not burn (in contrast to what was suggested earlier). Compounds with low intermolecular interactions such as carbon dioxide are used to extinguish fire, implying that something else besides the bond dipole is important.

By burning, however, most people refer to combustion reactions, where a compound reacts with oxygen (combustion is that reaction that allows your car to get enough energy from hydrocarbons). Combustion is therefore an oxidation reaction, and things that are more oxidized can be thought of as being more "burnt." In this sense, water burns all the time to make more oxidized compounds, such as hydrogen peroxide.

Lastly, you might be asking about just the "burning sensation" that water in different forms can give. If you touch hot water, congatulations, you will burn. If you touch ice, also, you interestingly have a similar sensation. So yea, water can "burn" when you take energy away from it.



** Update: I brought the oxidation point to tell people about one way of thinking of burning. Oxidation of hydrocarbons produces high amount of heat and that's what happens in regular combustion reactions.

Of course, whenever you have a redox reaction, you have to take the reduction potentials of everything involved into account in order to tell about spontaneity. I was not talking about spontaneity in the H2O2 example, I was refering to just one unconventional way to look at burning. People are really taking this point out of context.

Answer 3

Water doesn't burn because the intermolecular interactions between water molecules are too strong. H2O molecules have Hydrogen bonding between themselves, making the molecule very stable, and so it would take a super large amount of energy to excite the bonds between the molecules.

A side note: Hydrogen bonding occurs between a Hydrogen atom and either an Oxygen, Fluorine, or Nitrogen atom.

H-O
H-F
H-N

Answer 4

because further oxidation (basically what is going on when you burn something) is not energetically favourable. you do get H2O2 its known as hydrogen peroxide and is used for bleaching hair amongst other things (hence peroxide blond). but you cant get it by burning water you have to react things together to get the conditions required.

Answer 5

Not a Chemist. But the other answers does not take account of modern furnaces that inject steam under the firebox which serves two purposes, one it allows the ashes to separate. and two the heat of the existing fire, separates the compound back into its two gasses where they Burn most efficiently.

Answer 6

Because it is ALREADY burnt. Combustion of hydrogen in the presence of oxygen gives water, water is like ash for hydrogen.

Answer 7

Because it is stable, Hydrogen is highly flammable, water is not the combination removes the unstableness of the hydrogen.

Answer 8

what? you want O2 to oxidise O2- and then the former becomes O2- and the latter O2?
put it this way and you'll understand :)

Answer 9

Good question and a good answer from Vince ,

Answer 10

it does........every time i try to boil an egg!