Sciencemadness Discussion Board

If you heat sodium and NaOH until melt

vmelkon - 14-2-2014 at 14:10

If you heat sodium and NaOH until they melt, does the sodium dissolve into the NaOH?

I ask because there is the problem of producing sodium by electrolyzing NaOH. Careful temperature control is required otherwise it is said that you just end up with a metal fog in NaOH.

I want to do electrolysis of a small amount of NaOH.
I also want to try a small amount of CaCl2+NaCl.

Zyklon-A - 14-2-2014 at 14:49

Yes, if you heat it to much, sodium will dissolve in sodium hydroxide. At NaOH's melting point (318°C) sodium will not dissolve, but with more heating, (>330°C) it does dissolve.

BromicAcid - 14-2-2014 at 18:27

The sodium at that point is not dissolving in the sodium hydroxide, but reacting with the sodium hydroxide. That is why there is a temperature range instead of just trying to keep your NaOH molten. Read up on the Castner Cell, there is plenty of info out there. One of the reasons the current efficiency is low is due to your sodium reacting back with your electrolyte to give sodium oxide and hydrogen gas. Too high of a temperature and you basically get nothing.

[Edited on 2/15/2014 by BromicAcid]

vmelkon - 15-2-2014 at 04:57

Quote: Originally posted by BromicAcid  
The sodium at that point is not dissolving in the sodium hydroxide, but reacting with the sodium hydroxide.....


Were you talking about the case of electrolysis or the case of adding sodium to molten NaOH?

blogfast25 - 15-2-2014 at 06:40

Quote: Originally posted by vmelkon  

Were you talking about the case of electrolysis or the case of adding sodium to molten NaOH?


It makes no difference. In the case of electrolysis its the sodium that's been generated that reacts with the electrolyte. Sodium is sodium though.