why is water (H2O) not explosive?

Question

considering water contains the 2 most flammable elements in the known universe.... to a lay person it should be the most explosive

Answer 1

because they are together... so they become safe..

Answer 2

Yes, water can be explosive. The question you mean to ask is why doesnt water explode at room temperature and pressure with no external reactants?

To understand why this is you must first understand that being explosive isnt an elemental property there is more to it.

So what is happening during a chemically dependant explosion? You have a rapid expansion of a gas which is formed. A large amount heat can also be released.

How can this happen? Either in a chemical reaction, or decomposition of a substance.

With this said, water can undergo explosions in reactions which release a large amount of heat due to their thermodynamic favorability.

Given enough heat water will vaporize to rapidly form (steam) gas. So if a quick but great fluctuation in temperature occurred water could rapidly expand, and enough heat could form a plasma.


This should be good food for thought....

Answer 3

Another question from the "good old questions" list. Let me start with a short answer: Water will not explode, because it already has "burned".

It is true that hydrogen is an explosive gas, and it also needs oxygen to burn. But the key point lies in this question: What is burning? The answer is that burning is the process of reacting with oxygen to produce energy. (Well, to be really pedantic, it may be possible to use other gases such a Fluorine, but oxygen is so readily available, we usually mean oxygen.)

The burning process in the case of oxygen and hydrogen is relatively simple. If you put together suitable volumes of hydrogen and oxygen and provide a spark to start the reaction, one oxygen atom will combine with two hydrogen atoms, and will release energy in the process. The energy gets released in the form of molecular kinetic energy, and since the motion is random, this is exactly what we call heat energy. The gases heat up, and as all expanding gases do, they expand. That fast expansion of hot gases is what we call "an explosion".

What is the result of this burning/explosion? The answer is simple, if the proportions were right (one volume of oxygen for two volumes of hydrogen gas) all you get is water! Thus, water is _already burnt_. It is the "ashes" of hydrogen after it has burned.

If you wish to burn it again, you have to separate oxygen and hydrogen. But, to do that, you need to supply as much energy as is released when the burning occurred. This is possible by electrolysis.

The short answer is that ever since Dalton, we have known that the properties of a compound (like water) do not have any relation to the properties of the elements which it comprises. But lets look at why this is so.

You mention that H2 is explosive. What does this mean? It means that the H atoms have a lot of potential energy in their current state- they are not very stable. If those same atoms are attached to an oxygen atom, they are much more stable, and have much less potential energy. By the law of conservation of energy we know that when the hydrogen atoms switch from a high potential energy state to a low energy state, that energy has to go somewhere, and in fact this is the source of the light, heat, sound, etc. of the explosion you mention. A chemist would say this chemical change is exothermic (heat out).

Now picture those hydrogen atoms in a water molecule. They are already in a stable state, and do not posess the potential energy of H atoms attached to each other. They do not explode on contact with oxygen because they don't have energy to give off.

A good analogy is to imagine 2 rocks of exactly equal properties; one at the top of a hill and one at the bottom. You nudge the one at the top of the hill and notice it rolls away down the hill. You walk down and nudge the other rock and notice it doesn't roll away. Why not? It's already at the bottom!

Answer 4

A chemical explosive is a compound or mixture which, upon the application of heat or shock, decomposes or rearranges with extreme rapidity, yielding much gas and heat. Many substances not ordinarily classed as explosives may do one, or even two, of these things. For example, a mixture of nitrogen and oxygen can be made to react with great rapidity and yield the gaseous product nitric oxide; yet the mixture is not an explosive since it does not evolve heat, but rather absorbs heat.

For a chemical to be an explosive, it must exhibit all of the following:

Exhibit Rapid Expansion (eg. rapid production of gasses or rapid heating of surroundings), Evolution of heat, Rapidity of reaction, Initiation of reaction.

H20 exhibits none of these properties and is very stable. The activation energy to have oxygen dissociate from hydrogen in quite high and even then it is not explosive in nature.

It all comes down to the nature of the covalent bonds in the water molecule.

Answer 5

Why is Sodium Chloride not toxic? Because when two elements come together and form a molecule, they stop behaving like their base elements. There are thousands, millions of examples. In the case of water, the free electrons are bonded and not unstable - which is what makes the elements behave like they do.

Answer 6

Although those 2 elements are unstable apart they fuse together to become the stable element of water=H20 ..... Did you never take earth env. science or biology in high school. No offense ... but they do teach you that! I hope I helped

sincerly,
Giggles

Answer 7

The hydrogen oxygen bond is VERY stable. It takes a lot of energy to break them. When you separate the hydrogen and oxygen the hydrogen does become very flammable. Oxygen doesn't burn it is just one of the requirements to have a fire.

Answer 8

In simple terms -
The hydrogen oxygen bond is very strong and it is these bond that makes water (H-O-H) very stable. However, in some conditions, water can become "explosive"... (if it gets hot enough and it's expansion is restricted it becomes explosive)

Check out these links:
http://italianfood.about.com/library/snip/blsip015.htm?terms=1st+degree+burns
http://www.people.virginia.edu/~lz2n/articles/JPC01.pdf
http://www.geol.vt.edu/research/gssrs/gssrs2001/abstracts/atkinson.pdf
http://www.ornl.gov/~webworks/cppr/y2001/pres/117261.pdf
http://answers.yahoo.com/question/?qid=1006031503639

Answer 9

H2O molecules do not combust, hence they do not "burn." However, if enough heat is provided, water molecules can be turned from liquid to gas at such high speeds it will splatter, causing an "explosion."

Answer 10

Because Water is the oxidized product of hydrogen. It has already gone through its reaction to become what it is, it is now in its stable form.

Answer 11

table salt is made from two elements that are poisonous to humans yet we eat salt all the time...once the two elements join together they become an entirely different product that can have completely different qualities...