Is it possible to take a oxgen molecule and 2 hydrogen molecules, combine them and make a water molecule?

Question

need to know this for a science project {-_-}. also im curious.

Answer 1

Yes, it is certainly possible.
(The process is rather explosive though).

The reaction is as follows,
H2 + 1/2 O2 --> H2O
But generally we like to write chemical reactions with whole-number coefficients, so this becomes,
2 H2 + O2 --> 2 H2O

2 moles of Hydrogen gas (H2) and 1 mole of Oxygen gas (O2) react to form 2 moles of water (H2O).
We use Hydrogen and Oxygen gas (H2 and O2 respectively) because this is the two elements' natural states...you don’t often find just free H and free O atoms around, this is not very stable, so we have to use H2 and O2.

The water forming reaction shown above is very exothermic (a lot of energy is released in the form of heat). If you do this in a closed container, there is a good chance the container may explode due to the sudden increase in pressure during the reaction...so it is not advisable to try this without proper safety precautions.

It is interesting to note that although the pressure inside the reaction chamber increases while the reaction takes place, afterward, when everything is left to cool, the pressure actually goes down.
Both H2 and O2 are gasses to start out with. You begin with 3 moles of gas (2 moles of H2, 1 mole of O2). As the reaction proceeds, these 3 moles of gas react together to form 2 moles of water. Due to the exothermic nature of the reaction, the water which is formed is also in the gas state (steam). But now we are lacking 1 mole of gas inside a container with a definite volume. Once the temperature comes back down, the pressure inside will drop. Also, as the temperature drops, the water vapor will cool and condense into a liquid. Liquid water has a much smaller volume than water vapor, so that only further reduces the internal pressure.

Answer 2

Yes! Actually you can do this on a low/ impure level at home. The wooden periodic table site has a nice section about splitting water to get the hydrogen then using a lit split to recombine. If you don't have too much hydrogen you get a nice satisfying pop that sounds like a seal barking. In class we use a test tube to catch the bubbles, a metal like Mg and HCl to make the hydrogen.
Be careful though. You can definitely get to the danger level. If you are under 18 or overly brave get more hands on help before you try this.

Answer 3

Yes. Actually, it makes two water molecules.
H2 + O2 = 2H20
You can do that reaction by burning hydrogen or by doing it in a fuel cell. I forget what that's called, but it's the opposite of electrolysis.

Answer 4

you need special equiptment and the proper training on how to use it but yes you can