Sciencemadness Discussion Board

Na in NaOH? Viable way?

Varungh - 9-2-2026 at 22:52

Many of you must know of the castner cell. You put NaOH in, melt it and electrolyze the dry NaOH.
However there is a problem. The Electrolysis makes water, which dissolves and causes problems with the Na.
One can heat it higher and make it anhydrous, but then the Na will start dissolving in the NaOH.
So i was wondering if you can us ethe dissolved Na for any purpose. Maybe you can make ethoxide from it. Moreover if there is a way to selectively dissolve either in solution, it will be good for seperating Na from NaOH.
This would be good beacause it would mean you can just heat it as much as you like and electrolyze it to obtain dissolved Na.
This would be more stable too. The Na would not easily oxidise.

Keras - 10-2-2026 at 02:54

You can make K from KOH using Mg and tert-butanol in a way that NurdRage demonstrated in one of his videos, and which is also published in the famous book Small Scale Synthesis of Laboratory Reagents. It should work for Na, but apparently the reaction takes longer and the yield is not so good. But if you have metallic K, why bother about Na?

Varungh - 10-2-2026 at 08:51

Quote: Originally posted by Keras  
You can make K from KOH using Mg and tert-butanol in a way that NurdRage demonstrated in one of his videos, and which is also published in the famous book Small Scale Synthesis of Laboratory Reagents. It should work for Na, but apparently the reaction takes longer and the yield is not so good. But if you have metallic K, why bother about Na?


I do not have K, neither Mg(though Mg is trivially obtained as shavings)
Besides if we obtain a decent weight of the melt as Na(say 5%) then we would have 50g of Na in a 1kg NaOH melt. This would be rather accessible. Approx 5% by weight is not bad at all (if we can reach 5% that is :P)

Varungh - 10-2-2026 at 08:56

I thought long and hard about the problems and i have come with a few this may face-
How would you heat the NaOH? At higher temps, NaOH becomes insanely corrosive. A drop of water is all it takes to cause some serious tomfoolery.crucibles begone in seconds
The NaOH may precipitate as it cools(though this is not much of a issue really, but it may cause a layer of Na balls embedded in NaOH at the top)
Thirdly, the Na may short the cell.

bnull - 10-2-2026 at 11:26

Quote:
So i was wondering if you can us ethe dissolved Na for any purpose.

Is sodium metal soluble in ether? As far as I know, it isn't.

Edit: I found this article by J. L. Down et al., The Solubility of Alkali Metals in Ethers (https://pubs.rsc.org/en/content/articlelanding/1959/jr/jr959...), but I can't access it right now.

[Edited on 10-2-2026 by bnull]

Fulmen - 10-2-2026 at 11:30

I know the solubility of sodium increases with temperature, but won't the sodium precipitate out again once the bath cools?
Another solution to consider is to use vacuum to remove moisture. Not really practical on an industrial scale, but it should be possible in a laboratory setup.