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electrolisys of water

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rp181

Tue Nov 13 2007, 03:15AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

Im trying to get hydrogen from water, my current setup is 2 bottles connected with PVC ( hotglued). The top lid have holes, and hollow copper tubes are stuck down, these are the electrodes. Above the negative electrode, a glued a 2 liter soda bottle and ran 400ma 12v through. I cant tell if thi is working, am i doing it right?

Oh ya, i mixed the water with some baking powder, originally did salt in a bowl and it worked, but the i found out it made chlorine, dont want anything poisinous.

Cwazy

Tue Nov 13 2007, 03:30AM

Registered Member #1106 Joined: Thu Nov 08 2007, 01:15AM
Location: Seattle, Washington
Posts: 25

i sent u a pm regarding a how to for making one. its another forum so i dont wish to post it here.

uzzors2k

Wed Nov 14 2007, 03:57PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

I would ditch the baking powder and use NaOH, it doesn't vanish from the solution during electrolysis and it works as well as salt. No toxic chlorine either. For electrodes use graphite or high grade stainless steel, otherwise they will corrode away.

Bjørn

Wed Nov 14 2007, 05:05PM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

You also need to be careful if you collect any significant amount. Hydrogen ignites easily and is explosive over a large range of mixture ratios. Make sure you start out with the bottle completely filled with water so there is no air in it.

rp181

Thu Nov 15 2007, 12:14AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
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Posts: 1529

i tried using mechanicle pencil lead (.5mm) with salt earlier before this post, but when i checked it, the graphine on the cathode melted, and there were black bubbles above. what happened?

will the silicon steel from transformers work well (I-part).

as for collecting, not collecting much, mainly just expirimenting.

Shaun

Thu Nov 15 2007, 12:46AM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

The mechanical pencil lead did not work because it doesn't have enough surface area. Only lab electrolysis demos use rods as electrodes; when somebody is serious about collecting H2 or some other electrolysis product, they use plate (or large dia tube) electrodes.

The measure is Amps per square meter, or more commonly mA/mm^2. The lower this is, the less stress on your electrodes.

More surface area is also better because you will decrease resistance between the 2 electrodes which will allow more current flow at same voltage, yielding more H2 faster.

Oh and BTW when I used to electrolyze stuff, I just let the H2 mix with the Cl in the collecting container. You get a real nice bang out of that, just be sure to stay away from the resulting HCl gas! (apparently strong UV can ignite this mix, too, but I've never had that happen, even in direct sunlight)

Bored Chemist

Thu Nov 15 2007, 06:51AM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Also, mechanical pencil "leads" are held together with plastic/wax.
I'm sure a web search will tell you how to get the carbon rods out of batteries. These work much better.

rp181

Sat Nov 17 2007, 12:39AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
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ok, so i got 2 rods from 2 D-Batteries, im planning on using baking powder-water mix at armound 3 amps 12v. When u first get out the carbon rod, is anything required to make them safe? dont wanna touch till im sure :). anything i should be aware of?

Bjørn

Sat Nov 17 2007, 03:38AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

Give them a wash and wipe them really clean with paper. Then wash you fingers. That has always worked for me. The main thing that can go wrong is that you get electrolyte on your fingers and put them in your eye or mouth.

Remember that lower voltage is more efficient, you will find more posts about electrolysis by searching the forum.

JordanAutomations

Mon May 19 2008, 08:05AM

Registered Member #1487 Joined: Thu May 15 2008, 09:52PM
Location:
Posts: 3

Growing up, I think electrolysis was one of my favorite applications of chemistry. The carbon rods from D batteries were always good. Though I found out that the local jeweler used thicker and longer carbon rods for getting the slack out of their melting pots. Those worked real well.

I generally used carbon for the positive, where the oxygen would be. I would use a stainless steel rod for the negative electrode. Stainless didn't break down to particles as fast as the carbon did, and would last long. But the oxygen side would rust anything metal.

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