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Author: Subject: KOH crystals for electrolysis
haydz
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[*] posted on 21-6-2005 at 20:21
KOH crystals for electrolysis


Hi

I've just been reading a couple of books and one of them mentioned the electrolysis of potassium hydroxide to form potassium metal, it was described as being done by letting the KOH absorb some moisture in the air before electricity is run through it. It also said that the metal had to be stored under kerosene as it is very reactive. My question is, can I grow crystals in the same way as sugar crystals but for KOH (as my KOH is in the shape of a flat disc) for use in electrolysis (wouldn't the KOH just stay dissolved or what?) or am I missing something?

Thanks. Hayden.
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12AX7
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[*] posted on 21-6-2005 at 20:49


Don't worry about it, it has a low melting point. Mind that it attacks damned near everything, glassware is out of the question for anything for than a short test. Easy enough to throw it in a steel dish and set it on the hotplate.

Tim




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haydz
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[*] posted on 21-6-2005 at 21:13


argh thats so easy compared to what i was going to do.

for the electrolysis, have i missed anything out.. just leave the clump of KOH in the air for a while till its moist and then run electricity through it?
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neutrino
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[*] posted on 22-6-2005 at 02:24


I don't see why moisture is in any way necessary here. I'm sure the standard sodium synthesis has been described in a thread somewhere; it should be about the same thing.
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darkflame89
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[*] posted on 22-6-2005 at 04:13


Sounds like what BromicAcid did previously. IIRC, he put a little a NaOH on a watch glass, sprayed some moisture onto it and applied current to it. The water was first driven off. Due to the heat from resistance in the mixture, the space between the electrode was kept molten for sodium to be produced. The spacing between the electrode have to small.. There's a page in the forum that describes what he did, but i have forgotten where it was..



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BromicAcid
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[*] posted on 22-6-2005 at 04:20


I believe Davy is the one that actually preformed this experiment. He sat a block of KOH on a platinum sheet and drilled a hole in the top that he filled with mercury, he inserted the cathode into the mercury and connected the bottom sheet to the anode, when the block became damp from atmospheric moisture it was able to conduct, the circuit being around the block and electrolysis was able to commence giving a potassium amalgam at the cathode.

And as for growing a potassium crystal, good luck, your best bet is going to be simply heating KOH till it melts and pouring the shape you want from it. It will simply solidify into the shape you want that way, just don't have any water in your mold.

[Edited on 6/22/2005 by BromicAcid]
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akcapr
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[*] posted on 22-6-2005 at 19:14


the point of the water is probly to just get rid of the pores/pockets in the compound



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chloric1
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[*] posted on 22-6-2005 at 19:29


Quote:
Originally posted by akcapr
the point of the water is probly to just get rid of the pores/pockets in the compound


nope, sorry you are wrong. It is to ionize the alkali enough to conduct then when large amounts of current are going through the heat from the resistance melt part of the KOH.




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haydz
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[*] posted on 23-6-2005 at 22:10


I see the electrochemical sodium thread, and was wondering if the same procedure/s could be used with KOH rather than NaOH? K is more reactive and so it might be harder to get the K from it?
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