Downs Cell Electrical Insulator / Chemistry / Forums

Forums

4hv.org :: Forums :: Chemistry

« Previous topic | Next topic »

Downs Cell Electrical Insulator

1 2 3 next

Move Thread

LAN_403

Thomas W

Thu Feb 05 2015, 10:38PM

Registered Member #3324 Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276

I'm currently looking into building a small Downs Cell for making Sodium metal, mostly for the sake of seeing if I can do it.

the problem I have is trying to find a suitable insulator for the terminals that won't be effected by the high temperature of molten NaCl

Does anyone have a good idea as to what I could use?

thanks.
Thomas

Sulaiman

Thu Feb 05 2015, 11:35PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

seems complicated
for sodium metal you could try something like this

this video shows sodium by electrolysis with an easily available electrode/crucible

Thomas W

Thu Feb 05 2015, 11:55PM

Registered Member #3324 Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276

Sulaiman wrote ...

seems complicated
for sodium metal you could try something like this

That's true, however It's not very pure... and not quite as fun!

The concept of a high temperature insulator is the main issue...
Ideally it needs to not get corroded by molten salt and be able to withstand temperatures of over 800 Degrees *C

Other then that, no problem!

Sulaiman

Fri Feb 06 2015, 01:17AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

added one url above

Sodium metal on eBay

hardly seems worth the effort, except for the learning experience of course.

Thomas W

Fri Feb 06 2015, 08:29AM

Registered Member #3324 Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276

Sulaiman wrote ...

added one url above

Sodium metal on eBay

hardly seems worth the effort, except for the learning experience of course.

To the same degree it hardly seems worth building a go cart, tesla coil, your own house etc.. as someone else has done it for you.

Sulaiman

Fri Feb 06 2015, 11:09AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

for small quantities could you just use a borosilicate/pyrex 'U' tube
and insert anode and cathode from above, one each side?
you could use nichrome wire for electrical heating and possibly for both electrodes,
Wikipedia: Na melts at 98C, NaOH at 318C, Nichrome at 1400C and borosilicate softens at 830C, .... should be do-able

when the process is finished just smash the cheap/disposable tube under oil to retrieve the sodium for refining.
I have not tried, just an idea.

making or using large quantities of sodium is of dubious benefit

Did you look at the second youtube video that I pointed to?
it shows a simple ceramic crucible with electrodes.

Wastrel

Fri Feb 06 2015, 02:54PM

Registered Member #4095 Joined: Thu Sept 15 2011, 03:19PM
Location: England.
Posts: 122

Here be dragons. I recommend reading the sodium thread at sciencemadness from start to end.

Aside from chlorine being a war gas at the melting point of sodium chloride sodium metal has a vapour pressure of about a third of an atmosphere.

Molten sodium hydroxide eats glass.

Sulaiman

Fri Feb 06 2015, 03:05PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

Molten sodium hydroxide eats glass.
........................................... .
also, molten sodium eats glass

D'oh ! ....... sorry ! a completely stupid idea

Thomas W

Fri Feb 06 2015, 07:45PM

Registered Member #3324 Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276

Sulaiman wrote ...

for small quantities could you just use a borosilicate/pyrex 'U' tube
and insert anode and cathode from above, one each side?
you could use nichrome wire for electrical heating and possibly for both electrodes,
Wikipedia: Na melts at 98C, NaOH at 318C, Nichrome at 1400C and borosilicate softens at 830C, .... should be do-able

when the process is finished just smash the cheap/disposable tube under oil to retrieve the sodium for refining.
I have not tried, just an idea.

making or using large quantities of sodium is of dubious benefit

Did you look at the second youtube video that I pointed to?
it shows a simple ceramic crucible with electrodes.

Ah yes, that is not the same method as I want to go for, It is much less pure. I specifically want to use Molten Sodium Chloride so I can get the pure Chlorine and Sodium from the electrolysis I intend to use the Chlorine to make Hydrochloric acid & Hydrogen Peroxide(why not?) and the Sodium for fun / other science stuff.

I intend to have a stainless steel setup made by a machine shop next door who can do it for me cheaply.

Ash Small

Fri Feb 06 2015, 11:13PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Chlorine is THE worst enemy of stainless steel, especially 304.

Liquid sodium 'may' dissolve some of the metals in the alloy, not sure. (molten aluminium dissolves a bit of iron, for example.)

1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob