Separating hydrogen & Oxygen

[petethepainter]

Hi I offer my apologies if the answers to my question are already in the forums and would like to take this opportunity to 'Hi' as I have only just joined as a member.

 

I have been experimenting with electrolysis and and have enjoyed much of the information that I have gained from reading the threads here.... but! I would like to separate Hydrogen and Oxygen and seem to be having some problems.

 

1. If I use a brine solution then it appears I am only getting Hydrogen and Chlorine and not the Oxygen I require.

 

2. When I put any sort of divider between the diodes so as to keep the gases separate then I seem to get very little activity in producing anything.

 

Any help would be greatly appreciated.

 

Happy New Year - Pete

[Mercedes Benzene]

Welcome to Hypography! You're producing both hydrogen and oxygen when you use a brine solution. As long as there is a sufficient current, oxygen will be produced at the anode and hydrogen at the cathode. It's possible that the rate of electrolysis is not great enough for you to see much of any reaction, but if hydrogen is being produced, so is oxygen. Just remember that the oxygen is being produced in a volume that is half as much as the hydrogen... so that's another thing to consider.

 

As for appropriate setup, I would suggest reading up on Hofmann Aparatus: Hofmann voltameter - Wikipedia, the free encyclopedia

[Moontanman]

Actually when you use brine you do indeed get hydrogen and chlorine, I've done it, the chlorine is quite distinctive.

 

Sorry, i think you get sodium hydroxide and chlorine, I know I collected enough chlorine to have to evacuate several nearby classrooms!

[Mercedes Benzene]

Actually when you use brine you do indeed get hydrogen and chlorine, I've done it, the chlorine is quite distinctive.

 

I never said that no chlorine was produced, but if you're producing hydrogen, there is certainly the potential (no pun intended) to produce oxygen. You may have to worry about the chloride competing for the oxidation, but if you lower the concentration you should definitely get some oxygen.

If you have access to sodium hydroxide, or dilute sulfuric acid, I would recommend those instead of brine.

[Moontanman]

To be honest I was using a very strong brine solution, i got chlorine and sodium hydroxide. if you use a weak brine solution you should get oxygen and hydrogen. I was using close to 100 amps of DC current too. One of the those is a little current is enough them maxing it out should be better type experiments, it ended badly.

[petethepainter]

Thank you both for your speedy responses.

 

I will try to get another medium (sodium hydroxide, or dilute sulfuric acid) rather than the normal table salt that I am presently using. Would this then provide pure Hydrogen & Oxygen? I will still need to find a suitable way of separating the gases without the severe lack of production that I am getting at the moment.

 

I don't want to collect 'Browns Gas, HHO Gas, Oxyhydrogen Fuel) as I am fascinated by the Hydrogen fuel cell technology I recently read about and to experiment I would need pure Hydrogen and would rather use concentrated Oxygen rather than than use the surrounding air.

 

I will check the link (Hoffman voltameter) Thank you again.

[modest]

I will try to get another medium (sodium hydroxide, or dilute sulfuric acid) rather than the normal table salt that I am presently using.

 

;)

 

You want to use an electrolyte with a cation that has greater standard electrode potential than a hydrogen ion and an anion with less standard electrode potential than hydroxide. Something that you might easily find would be magnesium sulfate, MgSO₄, sold as epsom salt which you could probably get at any pharmacy. Magnesium has a lower potential than hydrogen and sulfate, like with sulfuric acid, works well as anion.

 

But, definitely, salt is not your best option. :)

 

Would this then provide pure Hydrogen & Oxygen?

 

Yes.

 

I will still need to find a suitable way of separating the gases without the severe lack of production that I am getting at the moment.

 

Usually test tubes are inverted with the anode and cathode set up into them like so,

 

http://www.saskschools.ca/curr_content/chem30_05/graphics/6_graphics/electrolysis_water.gif

 

EDIT--> Speaking of which, what are your anode and cathode made of? You could have trouble if they are copper. You don't want to use a metal which reacts in the cell—platinum is often recommended. <-- EDIT

 

I will check the link (Hoffman voltameter) Thank you again.

 

I agree with MB, that would be extremely useful. You want to be somewhere between 3 and 6 volts I believe.

 

~modest