Assuming a scientist has two canisters: One with a liter of pure gas of hydrogen (single atoms gas), and one with half a liter of pure gas of oxygen (single atoms gas).

The scientist desires to conjunct the two single atom gasses inside some instrument somehow, to create water.

I understand that the process of doing so is some kind of explosion.

What are the names of that reaction and of the instrument in which it should take place?

I ask this after I saw the film "The Martian", in which the protagonist "Mark Watney" created water from separating hydrogen from hydrazine, then burning it with oxygen in extremely low stream of gasses, creating very small amount of water in each step of a process.

Here is a video in which a youtuber seemingly creates water from burning hyrdogen and oxygen (legal note: I ask any reader not to try this without being certified as a chemist from, a internationally known academic center).

This question is for general knowledge: To know the name of the reaction and the common instrument for it.

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    $\begingroup$ Hydrogen and oxygen are not "single-atom gases". $\endgroup$ – Loong Mar 24 '18 at 18:16
  • $\begingroup$ @user9303970 single hydrogen/oxygen atoms are very unstable and don't occur naturally. Hydrogen and oxygen gases are diatomic gases ($\ce{H2}$ and $\ce{O2}$, respectively). $\endgroup$ – Felipe S. S. Schneider Mar 24 '18 at 18:28
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    $\begingroup$ @user9303970 Unstable here means that the bond dissociation energy in diatomic hydrogen and oxygen is 436 kJ/mol and 498 kJ/mol, respectively. To give you an idea, see also atomic hydrogen welding. $\endgroup$ – Loong Mar 24 '18 at 19:11
  • $\begingroup$ What do you want with an actual apparatus and safety instructions for a hypothetical reaction?!? Total nonsense. Burning hydrogen with oxygen is done with a torch, in the same way as the one used for oxy-acetylene welding. $\endgroup$ – Karl Mar 24 '18 at 21:24
  • $\begingroup$ I didn't ask for "safety instructions" anywhere, and even if I would, calling a good question for general knowledge with different possible benefits to those who will read it is redundant. $\endgroup$ – user9303970 Mar 24 '18 at 22:14

Having a single atom hydrogen or oxygen gas means having lots of free radicals just waiting to react with their own species, liberating a huge amount of energy within a fraction of a fraction of a fraction of a second. This is very unstable.

Lets say the hydrogen only reacts with oxygen and vice versa, then such a reaction would be possible. In general it is called radical addition or free radical addition when radicals react with each other.

The bond energy of a O-H bond is about 464 kJ/mol.

If we had 1 mol magic $\ce{O.}$ ( the oxygen radical) gas and 2 moles magic $\ce{H.}$ the result would be 1 mol (normal) $\ce{H2O}$ and 928 kJ energy. This is the energy delivered by 221.8 g of TNT.

This reaction should be slow or taking place in an explosion proof container.

If you did the same with ordinary oxygen and hydrogen, the energy liberated would still be high but not as big as with radicals ( the O-O and H-H bond needs energy to be opened).

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  • $\begingroup$ So much thanks Legolas ! If I understood you correctly, it will be less energetic, hence a bit less explosive, to create water from dihydrogen+monooxigen? This is the only way to create the water? $\endgroup$ – user9303970 Mar 25 '18 at 15:16
  • $\begingroup$ There is no stable monooxygen, you have to say dihydrogen reacts with a half dioxygen. $\endgroup$ – Legolas Mar 25 '18 at 16:19
  • $\begingroup$ There are many ways to create water, all condensation reactions liberate water ( They are extremely common). $\endgroup$ – Legolas Mar 25 '18 at 16:22
  • $\begingroup$ I thought that in the film "Bring Him Home" (with Matt Damon), he actually separated atoms of hydrogen from hydrozine, then mixed with oxygen in low doses, just to make small amount of water each time again. $\endgroup$ – user9303970 Mar 26 '18 at 15:27
  • $\begingroup$ This is true, but unfeasible. $\endgroup$ – Legolas Mar 27 '18 at 16:42
