Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: scotty234 on 13/09/2005 20:59:31

Title: H²O
Post by: scotty234 on 13/09/2005 20:59:31

1

Title: Re: H²O
Post by: daveshorts on 14/09/2005 15:01:06

In the simplest case you just pass a current through water and it will split into hydrogen and oxygen. To make it work well you have to be careful that your electrodes won't oxidise and absorb the oxygen and water is not very conductive so you want to add something like magnesium sulphate to the water which will increase the conductivity and not decompose itself...

Title: Re: H²O
Post by: Simmer on 15/09/2005 19:32:48

Also the electricity needs to be DC, eg from a battery.  Using the AC mains would not only probably be fatal but also, worse, wouldn't work! [:)]

Title: Re: H²O
Post by: Simmer on 15/09/2005 20:12:56

Sorry, Ruzz5000, you also asked how the process worked.

This webpage gives a reasonable explanation of what's going on, it shows some other electrolysis experiments too but I would give the molten salts a miss, if I were you. [:D]

It's good because it also explains why you need to add an electrolyte and why Daveshorts recommended magnesium sulphate.

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch20/faraday.html#water

As Daveshorts also said, you need a non-corroding electrode, just copper wire won't give you a lot of oxygen (although you should still seee the hydrogen at the cathode).  This next webpage shows you how to make carbon electrodes and also quite a good design for the apparatus, if you can find all the bits.

http://www.science-projects.com/Electrolysis/eDevice.htm

Title: Re: H²O
Post by: weebrain on 17/09/2005 02:05:52

i know another way of doing this u very rapidly heat the water using something like thermit, and as u might guess it becomes a wee bit fun.


sir loony

Title: Re: H²O
Post by: Simmer on 18/09/2005 11:10:57

Never heard of that one!  Don't you find the jets of super-heated steam a bit of a nuisance? [:)]

Also wouldn't the hydrogen and oxygen recombine, possibly explosively, when they cooled down a bit?

Title: Re: H²O
Post by: daveshorts on 20/09/2005 10:01:27

I would be surprised if heating water with thermite will split the water into hyrogen and oxgen - a few molecules may split because there is so much energy kicking around, but they would recombine pretty quickly afterwards and you certainly couldn't split the two off in seperate places. You would manage to make quite an effective explosion, but not split the water..