Sciencemadness Discussion Board

Sodium Hydroxide reduction

35lightning35 - 24-4-2016 at 13:00

is it possible to reduce NaOH using aluminum to form sodium metal?

[Edited on 24-4-2016 by 35lightning35]

solitanze - 24-4-2016 at 13:07

Yes it will work but the yield is pathetic and you'll need a way to separate the sodium metal from the reaction products.

Not worth it IMHO. Personally, if I wanted sodium I'd look for the electrochemical methods. Or just buy the stuff, it's not that expensive.

35lightning35 - 24-4-2016 at 13:25

Quote: Originally posted by solitanze  
Yes it will work but the yield is pathetic and you'll need a way to separate the sodium metal from the reaction products.

Not worth it IMHO. Personally, if I wanted sodium I'd look for the electrochemical methods. Or just buy the stuff, it's not that expensive.

for the electrochemical method, would electrolysis of molten sodium hydroxide work?

solitanze - 24-4-2016 at 13:37

Yes, it's called the Castner process but it's quite dangerous. Molten sodium hydroxide is extremely caustic. I once tried this back in my stupid days, using an improvised apparatus, it bubbles and splatters everywhere and the vapours are very unpleasant.

This is not something a beginner should attempt IMHO.

Velzee - 24-4-2016 at 17:32

Quote: Originally posted by solitanze  
Yes it will work but the yield is pathetic and you'll need a way to separate the sodium metal from the reaction products.

Not worth it IMHO. Personally, if I wanted sodium I'd look for the electrochemical methods. Or just buy the stuff, it's not that expensive.


EDIT: I read this completely incorrectly. I thought the OP asked if it was possible to reduce NaOH to sodium metal when in solution. My apologies.

This doesn't make sense. Na is far more reactive than Al, therefore Al will not replace it, especially in a solution. I know it is possible via thermite. But, even if it did replace it then, it would be still impossible for you to collect the metal, as it would simply react with the water:

3NaOH + Al --> 3Na + Al(OH)3

2Na + 2H2O ---> 2NaOH + H2

Instead, NaOH reacts with Al to form Na3AlO3

6 NaOH + 2 Al ---> 3 H2 + 2 Na3AlO3

[Edited on 4/25/2016 by Velzee]

IceDahl - 25-4-2016 at 00:47

NightHawkInLight has some great videos about isolating potassium and sodium metal:

https://www.youtube.com/watch?v=2oF5bABrTsQ
https://www.youtube.com/watch?v=seSg_GWj1b0
https://www.youtube.com/watch?v=RJ21jQiOv2E

35lightning35 - 25-4-2016 at 01:57

Quote: Originally posted by IceDahl  
NightHawkInLight has some great videos about isolating potassium and sodium metal:

https://www.youtube.com/watch?v=2oF5bABrTsQ
https://www.youtube.com/watch?v=seSg_GWj1b0
https://www.youtube.com/watch?v=RJ21jQiOv2E


I've seen these videos, and I was thinking if it was possible to use aluminum instead of magnesium

chornedsnorkack - 25-4-2016 at 09:17

If anything, Al should be better than Mg.
Boiling points:
Al: 2470 degrees
Al2O3: 2980 degrees
Mg: 1090 degrees
Na: 880 degrees

So, would the reaction
Na3AlO3+Al->Al2O3+3Na
go to right when Na alone is distilled off, well above 880 degrees?

solitanze - 25-4-2016 at 09:54

I believe the 'thermite' reaction is 6 NaOH + 4 Al --> 6 Na + 2 Al2O3 + 3 H2. In a side reaction, NaH is also formed.

You would need some elaborate apparatus to contain the sodium metal. Again, such reactions are messy and not worth it IMHO.

Take a look at the electrochemical sodium thread. Electrolysing molten sodium hydroxide would be easier though not without dangers.