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| Slightlymadscience |
 Posted: Tue Apr 01, 2008 11:42 am Post subject: Advice on scaled-up H20 Electrolysis experiment? |
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Forum Freshman
Joined: 31 Mar 2008
Posts: 7
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I've done small-scale H20 and NaOH electrolysis with test tube/beaker (crucible with NaOH) set ups using DC batteries and carbon electrodes. My question comes up after scaling up considerably.
Useful info:
I built a plexiglass tank (holds at least 5 gallons) that has gas traps on either side (with valves), and the electrodes are an array of 11 stainless steel plates (switch plate covers) on either side. The electrodes are separated by a distance of over 30 cm. The power supply is an old solid-state car battery charger (12 volts, settings of 2/5/10 amps). I've used tap water, and distilled water, and have tried NaCl and NaHCO3 (table salt and baking soda) as electrolytes.
I based my design on a project done by someone else, but they wanted didn't need to separate the Oxygen and Hydrogen, so their array was a series of alternating anode/cathode plates that were close together. His reaction was VERY energetic, and produced a lot of gas quickly.
His electrode array (1): +-+-+-+-+-
Mine (2): ++++++ -------
When applying the current, bubbles form on both electrodes, but VERY slowly. I'm wondering if the difference in effect is due to the distance the current must travel between anode and cathode. I haven't found any resources that could verify this, however.
Any insight would be appreciated.
Thanks in advance.
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| SteveF |
| Posted: Tue Apr 01, 2008 1:35 pm Post subject: |
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Forum Senior
Joined: 28 May 2007
Posts: 367
Location: NC USA
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| Quote: |
| ...due to the distance the current must travel between anode and cathode. |
Your guess is correct. The distance between the terminals is an important factor.
Measure the electrical resistance of your electrolyte (NaOH) solution between the terminals. It is probably quite high. That means your cell draws low current. Low current means a low rate of electrolysis.
Bringing the terminals closer reduces the electrical resistance. Of course, if they are too close, the current draw may be too great and your battery charger can overheat. But your hypothesis for slow rate is correct.
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| Pong |
| Posted: Tue Apr 08, 2008 3:42 am Post subject: |
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Joined: 08 Apr 2008
Posts: 314
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| I do this inadvertently, taking rust off old tools and antiques. I think you could keep the bubbles separate - and prevent a short - with some layers of fabric. |
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