chornedsnorkack - 18-6-2016 at 05:31
Well, how is it possible?
The initial reaction might be:
cathode: Na++e-->Na
anode: 4OH-->O2+2H2O+4e-
However, the problem is that Na is formed. So the next reaction could be:
2Na+2NaOH->2Na2O+H2
With the net result being
4NaOH->2Na2O+2H2+O2
and no metal Na formed. Dry Na2O is solid until over 1100 degrees.
Thus: why is electrolysis of molten alkali possible, rather than producing only solid alkali metal oxides?
[Edited on 18-6-2016 by chornedsnorkack]
Jstuyfzand - 18-6-2016 at 05:45
Problably wrong here but I dont think any Na is formed because of its reduction potential.
blogfast25 - 18-6-2016 at 06:11
@chornedsnorkack:
You should find any answers to questions about molten NaOH electrolysis here:
http://www.sciencemadness.org/talk/viewthread.php?tid=9797
Marvin - 18-6-2016 at 06:26
Keeping the melt cool, just above freezing, reduces sodium oxide production, reduces solubility of the metal and reduces diffusion of the metal and
water.
I'm fairly sure the answer I got 20 years ago from a sodium chemist is that the reaction doesn't happen, and that's difficult to square with the
literature, but certainly in trying to make sodium I've produced solutions of sodium in anhydrous sodium hydroxide that have deposited sodium metal on
freezing.
Good question, I wish I had a more definitive answer.