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KOH from batteries Rate Topic: -----

#1 elementcollector1 


Baryon
If you go to Wiki and search 'alkaline battery', you get the picture attached. Wiki says this is pure KOH. So, I was wondering how to force a battery to leak in that way? Would recharging an AA with a 9V work?
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#2 John Cuthber 


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Chemistry Expert
"Wiki says this is pure KOH."
Wiki is wrong.

and it's not a good idea to mess with batteries in that way.
If you want KOH you are better off leaching bonfire ashes and adding slaked lime.
What's this signature thingy then? Did you know Santa only brings presents to people who click the + sign? -->
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#3 elementcollector1 


Baryon
You're right, I have sort of pale orange crystals. So much for efficiency, then.
I tried the potassium chloride / calcium hydroxide route, and faint bubbling was heard (reaction?) I now have a massive amount of solution that is slowly evaporating to give (so far) clear crystals. Can these be dehydrated through blowtorch or Bunsen burner?
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#4 Suxamethonium 


Baryon
You could try Ca(OH)2 and K2SO4 to yield the KOH in solution... but then you would have to dry to K2O and rehydrate just enough to get KOH again (if you want dry KOH). If you're going to do that you may as well just decompose K2CO3.
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#5 John Cuthber 


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Chemistry Expert
" I now have a massive amount of solution that is slowly evaporating to give (so far) clear crystals. "
Do you know that
1 KOH is very hygroscopic.
2 KOH solutions rapidly pick up CO2 from the air and are converted to K2CO3?
What's this signature thingy then? Did you know Santa only brings presents to people who click the + sign? -->
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#6 elementcollector1 


Baryon

View PostJohn Cuthber, on 9 February 2012 - 03:00 PM, said:

" I now have a massive amount of solution that is slowly evaporating to give (so far) clear crystals. "
Do you know that
1 KOH is very hygroscopic.
2 KOH solutions rapidly pick up CO2 from the air and are converted to K2CO3?


Yes, I do. Turns out that Ca(OH)2 had no reaction whatsoever. I got cubic crystals and nothing else.
Where do I get potassium sulfate?
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#7 John Cuthber 


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Chemistry Expert
" Turns out that Ca(OH)2 had no reaction whatsoever."
How do you know?
"Where do I get potassium sulfate? "
I usually get it from the gardening store. Adding dilute sulphuric acid to the K2CO3 leached from ashes works too.
What's this signature thingy then? Did you know Santa only brings presents to people who click the + sign? -->
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#8 elementcollector1 


Baryon

View PostJohn Cuthber, on 10 February 2012 - 06:20 PM, said:

" Turns out that Ca(OH)2 had no reaction whatsoever."
How do you know?
"Where do I get potassium sulfate? "
I usually get it from the gardening store. Adding dilute sulphuric acid to the K2CO3 leached from ashes works too.


When the crystals were evaporated (that should have been the first clue right there), they were rectangular salt crystals. I don't think KOH crystallizes in this manner.
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#9 John Cuthber 


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Chemistry Expert
Plants don't generally bother much with sodium chloride.
What, exactly, did you do?
What's this signature thingy then? Did you know Santa only brings presents to people who click the + sign? -->
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#10 elementcollector1 


Baryon
I took sodium-free salt, and dissolved it in solution. Then, I took some calcium chloride and sodium hydroxide and mixed them to form calcium hydroxide. Then, I placed that in the potassium chloride solution, and faint bubbling was heard.
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#11 John Cuthber 


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Chemistry Expert
Why did you think that might work?

Anyway, if you leach ashes with water you get K2CO3. If you concentrate that solution down and then add Ca(OH)2 you get CaCO3 and KOH. The Ca(CO3 is very insoluble so that drives the reaction to give KOH.
If you boil off the water you can get solid KOH.

What do you want KOH for?
What's this signature thingy then? Did you know Santa only brings presents to people who click the + sign? -->
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#12 elementcollector1 


Baryon
Catalyzed reduction with Mg, production of potassium permanganate, etc.
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