Cou
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Elemental bromine, electrolytic method
In this video, bromine is made by electrolysis of a sodium bromide solution with hexavalent chromium. My quick question is, will this still work if I
do it with thin 3-gage platinum wires for both electrodes, instead of carbon? Since the platinum wire has less surface area than large carbon rods, it
might not work right
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Metacelsus
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I've used a platinum coated titanium anode. Pt works, but the limited surface area would slow down the reaction.
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Cou
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I thought that in electrolysis, the surface area of the electrode doesn't change the rate of reaction, as long as you have the same number of amps
going through it. It just means the electricity comes out of a smaller area, instead of being spread out, so the electrode corrodes faster. Which
isn't a problem with platinum
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phlogiston
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True, although at some point the rate at which ions can diffuse to the electrode surface becomes limiting.
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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hyfalcon
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You might be surprised what the harsh conditions in an electrolytic cell can do to platinum. It's slow but there's still degradation, especially when
you have to great of a charge density on your anode.
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Cou
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So it'll work just as well as carbon, if I wrap a large amount of wire into the solution for more surface area. And thin platinum wire from
elementalscientific.net is affordable, it's like $8 per roll
[Edited on 12-10-2014 by Cou]
[Edited on 12-10-2014 by Cou]
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hyfalcon
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Reduce your current and up your run time.
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Dan Vizine
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Cou, what's the goal here? To obtain Br or to do electrolysis?
If you only want the Br for another purpose, NaBr + H2SO4 + KMnO4 is much easier.
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MrHomeScientist
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I'm guessing the video you mention is mine: https://www.youtube.com/watch?v=NKjyM2AkZSY (because at the time I posted it, it was the only one on YouTube! Not sure if there are others now)
I agree with hyfalcon about reducing your current to put less stress on your electrodes. Platinum is good stuff, but not invincible! I really liked
this method vs others because it produces very little fumes. Pictures of distillation rigs filled with dense bromine gas have always made me uneasy
for when it comes time to disassemble things. I also like electrolysis because it uses very OTC materials (except the dichromate, but that's not
strictly necessary).
This was probably my favorite experiment I've done so far, and bromine is one of my favorite elements.
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