Instructables

Bonding hydrogen and oxygen to make water?

Ok, so I got how to get water, but how do I condense it without losing much, and would it be at least a semi-efficient and/or fast way of obtaining around a cup of water?

So, I have another question. I know, I've been posting a new question at least once a week for a while now and you're all probably like "Dark Master87, Y u no shut up and stop trying to do impossible things?? w(O;O)w" Most people on here probably know about electrolysis and seperating water into hydrogen and oxygen with electricity, but it's simple and I don't currently have a use for it. But does anyone know how to bond hydrogen and oxygen to create water? I'm expecting there to be heating or cooling involved, probably more likely heating. Would you light the two gases on fire? Or would they just automatically bond with each other at the point of contact? More importantly, would this be possible to acheive on the limited budget of a 14 year old hobbyist who *may* have access to *some* lab equipment, but probably not? Thanks for paying attention, if it's not feasible/possible, I won't mind if you nag about me never doing any reasonable projects. And also, how hard would it be to get the hydrogen and oxygen from electrolysis with losing too much of it? 

FoolishSage3 years ago
When hydrogen burns in air you produce water vapour. A complicated way to do this would be to use a fuel cell which would allow you to harness the energy generated by the reaction but if all you want is to combine hydrogen and oxygen just let hydrogen loose in air and add a source of ignition (spark or flame). Be careful however: hydrogen burns very easily and with allot of energy. Even small amounts of hydrogen burn with a pop. Any significant amount will simply explode. Fire and explosions are dangerous. Stay away from them and dont do any of this without adult supervision.

All that said, joining hydrogen and oxygen is not the most interesting thing in the world..
ALogan97 (author)  FoolishSage3 years ago
Thanks, that's pretty much what I guessed. Is there any way that I can bond a lot of it together quickly and then condense the water without losing much? Also, would an electric spark work or would I have to use a heat spark? I'm guessing it doesn't matter, but just making sure. And would using a spark make the water it produces cooler and/or easier to condense into a liquid?

And I know, it's not the most interesting thing to just bond the gases, but the project I'm going to use it for if I can find a way to do it quickly and/or efficiently will be much more interesting.
Any source of ignition will set off the hydrogen-oxygen reaction; a flame or an electric spark are the simplest. Off the top of my head there are two ways to cool the water:
1. bond hydrogen and oxygen in a fuel cell. This will generate the least heat during the reaction.
2. use a kind of heat exchanger after the reaction to condense the vapour.

Seeing how the H-O reaction is usually explosive I would not suggest you try to capture it in a closed environment. This means you will probably have some losses but at least your equipment wont blow up in your face. If you absolutely must capture as much as possible consider using either a flexible reactor or a reactor with an expanding component to catch the pressure wave.

The ideal set-up I think would be something like this:
A strong steel reactor with an air-tight seal rated for high pressures and 5 ports. One port for the entrance of oxygen, one port for the entrance of hydrogen, one port for the ignition, one port to recover the vapour and take it to a condensation rig and finally but most importantly: one port for an automatic safety valve rated BELOW the WEAKEST component in your system (if there is a problem then the safety valve catches it rather than something more dangerous/expensive). The condensation rig can be a simple water cooled condenser found in most highschool labs, as long as it can stand the pressures involved.

ALogan97 (author)  FoolishSage3 years ago
Thanks, just one more thing. Do you think I could fit the whole system into a large thermos or similar portable object? If it could, that would be awesome, but if not it should still be ok and I could make it bigger.
getting gas storage, reactor, cooling and safety equipment into a thermos would be tough but not impossible. It all depends on what size equipment you can get your hands on.
ALogan97 (author)  FoolishSage3 years ago
Well the gas storage would be outside of the thermos for ease of refilling (probably something like a bottle/canister that screws onto the bottom of the thermos), so that should make it easier. Thanks for helping!
There are many ways to combine hydrogen and oxygen to get water.

A cheap, easy, and relatively safe, way to do this is shown in this 'ible:
http://www.instructables.com/id/Make-a-Ballistic-Bubbles-Machine/
This machine produces foamy soap bubbles filled with hydrogen and oxygen, and the bubbles can be subsequently ignited with a barbecue lighter.  It's not obvious that this machine is breaking then making water, as you'd have to run it for a while, probably hours, to notice water disappearing from the electrolyzer.  The water being formed on the soap bubble side does so in the form of steam, and a lot of this water is being lost to the air surrounding the exploding soap bubbles.

Another easy and safe way to combine hydrogen and oxygen to get water, is by feeding these gasses into a PEM fuel cell.
http://en.wikipedia.org/wiki/Proton_exchange_membrane_fuel_cell
There are toy sized versions of these fuel cells, but they tend to be expensive toys. 
http://www.horizonfuelcell.com/index.htm
Fuel cells that can make significant amounts of electricity, e.g. enough to do something useful, like run a laptop, circa 50 watts or so, tend to be very expensive.

You can also burn hydrogen in air, in a torch
http://en.wikipedia.org/wiki/Oxy-fuel_welding_and_cutting#Hydrogen

Also you can burn hydrogen and air in an internal combustion engine. There are bunch of videos on Youtube of people running lawn mowers, and other engines on hydrogen.
http://www.youtube.com/results?search_query=hydrogen+lawn+mower

Also you can cook your burgers, hot dogs, etc, with it.
http://www.youtube.com/watch?v=GVVj168f-t8
ALogan97 (author)  Jack A Lopez3 years ago
Thanks for answering, but I needed to find a way to not only make the water, but keep it and then condense it. I've pretty much got it figured out, but if you have any idea how to make or where to buy a cheap, simple, efficient condenser that could fit into a thermos along with a hydrogen/oxygen reacting chamber and safety valve, it would definitely help.
Vyger3 years ago
A combustion engine using hydrogen makes water vapor for the exhaust. If it condenses in the exhaust pipe pure water drips out. An engine that has been set up to run on propane would probably be able to use hydrogen. It just mixes it with air for the O2 and then a spark sets it off. It would be the safest and most contained way that you have access to to make water. You are basically harvesting the waste product which is water. It would take a lot of Hydrogen to run an engine though. Probably not cheap, which is ironic since it it the most abundant element in the universe by far.
ALogan97 (author)  Vyger3 years ago
Yeah, I knew that part. I guess the real question is how efficient this would be and how I could easily condense the water without losing much. Fortunately I won't need as much as an engine would need, because as you said, hydrogen is expensive. For my purposes I can get enough of it through electrolysis and then bottling the hydrogen.