OT Water splitting

[harryagain]

Came across this, interesting.

[Bob Minchin]

We did this at school in the 60's???

[Bob Eager]

So did we. And I did a project on water joining too...

[Jonno]

Bob Eager scribbled

My school was rubbish, we never did turn water into wine.

Only the other way round.

[Andrew Gabriel]

Yes, I went home and setup some electrolysis using a car battery which produced hydrogen at a fast enough rate to generate a small continuous flame. I never got any oxygen off, as I couldn't afford expensive enough electrodes which didn't instantly react with the oxygen ions produced. I had a plan to fill a balloon with the hydrogen and oxygen mixture liberated, and to release it to float up with a length of string attached to act as a fuse so it went bang at some height, but lack of oxygen meant I never got as far as trying it (although it would have worked without the bang even with just hydrogen).

[Brian-Gaff]

Yes not very efficient though is it. The problem with the oxygen electrode getting polluted by Oxides is rather annoying. Eventually you have to replace the electrode. Still I did try making batteries out of lemons once. Brian

[Chris Hogg]

I imagine graphite would have been OK for the electrodes, such as the central positive electrode stripped out from traditional zinc-carbon batteries.

IIRC there used to be (~1950's or 1960's?) a little hand-held electrolysis cell available for micro-welding that burnt an oxy-hydrogen flame. Looked a bit like two Sparklets soda-syphon CO2 ampoules fixed together and of about that size, with a burner tube coming off. Don't know the power supply; car battery? Never had one; always wanted one! Probably discontinued due to too many people having their hands blown off.

[Andrew Gabriel]

Car battery was the power supply, not the electrolysis cell.

I rather suspect the oxygen ions will react with it, giving you carbon dioxide. That's the problem with most metals - you get the oxides produced rather than liberating oxygen, unless you go for platinum or gold or something else expensive.

Mine was in a jam jar with a small hole in the lid, which you could light to get a flame. The hydrogen electrode was a tall screening can from an intermediate frequency transformer screening cover, and I suspect I used lots of copper wire closely spaced inside it for the oxygen electrode (which just produces copper oxide, and salts as a result of reacting with the salts added to make the water more conducting).

[Nightjar]

Water electrolysis oxy-hydrogen micro-welders are still sold for the jewellery trade, although they are probably a bit more expensive than the one you remember. The one I had in my business used MEK as a flame modifier, which presumably was to avoid explosions.

[Chris Hogg]

Apparently not. See

although I've read elsewhere that carbon electrodes do eventually deteriorate and crumble, but probably OK for short demos and home experiments.

[newshound]

I used to use a bench-based equivalent for welding thermocouple junctions (early 70's). Ran off a 13A socket but not sure what power it drew. I think it used standard hypodermic needles as the nozzle.