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Offline constant thinker

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Separating NaCl
« on: March 18, 2006, 11:48:20 AM »
Can separating NaCl be done using electrolysis or will it decompose thermally at a reasonable temperature?

Also is is 2Na + Cl2 -> 2 NaCl an exothermic reaction/will it blow up in my face?

My intention is to get a little bit of Sodium metal.
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Offline Alberto_Kravina

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Re:Separating NaCl
« Reply #1 on: March 18, 2006, 01:27:23 PM »
Quote
Can separating NaCl be done using electrolysis or will it decompose thermally at a reasonable temperature?
Yes- it can be separated by electrolysis of NaCl(l). You can't separate NaCl just by heating.

If you electrolyze NaCl(l) both electrodes should be distanced from each other, otherwise the reaction between sodium and chlorine takes place (boom!)

« Last Edit: March 18, 2006, 01:30:36 PM by Alberto_Kravina »

Offline constant thinker

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Re:Separating NaCl
« Reply #2 on: March 19, 2006, 06:37:02 PM »
Basically it sounds like this won't be happenings anytime soon. Thanks guys for the information.
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Offline jdurg

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Re:Separating NaCl
« Reply #3 on: March 22, 2006, 11:22:11 AM »
Don't forget that you cannot electrolyze an aqueous solution of NaCl, aside from using a mercury cathode.  Even then, you have to deal with the separation of your mercury from your sodium.  Trying to separate the two isn't easy because the surface area of the amalgam will result in near instant oxidation of your sodium once the Hg has evaporated away unless you do this in a dry box.
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Offline constant thinker

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Re:Separating NaCl
« Reply #4 on: March 22, 2006, 05:25:26 PM »
I realized that you can't electrolyze NaCl in an aqueous solution. That is why I was planning on melting it down then electrolyzing it so that Cl2 would just come off and/or collect on the - Electrode. Hopefully when I was done I'd be left with some Na. Then I would immediately put the pot/whatever I used to heat the NaCl in up into a pot (or bucket) of cold water to try to cool it down.

That is why I asked about thermal decomposition. Also I found that NaCl doesn't melt until about 800°C, which is about 1400°F (I'm estimating in my head). My stove doesn't read 800°C, so I decided I wouldn't be carrying out this expirement.
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Offline jdurg

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Re:Separating NaCl
« Reply #5 on: March 22, 2006, 09:49:27 PM »
Yeah, we've had a bunch of posts here at the forums asking how to make sodium from NaCl and it's really not economically feasible for the home chemist looking to make "small" amounts.  In addition, Na melts a little below 100 C and boils around 880 C so any Na that is formed will most certainly be molten.  This makes it FAAAAAAAAAAAAAR more dangerous than most people realize as the molten NaCl has a very large surface area and will readily react with any H2O or O2 in the air.  The last thing you want is molten Na and NaCl flung onto you or your belongings.   ;D  (Trust me.  Molten Na on your flesh hurts like you wouldn't believe).
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Offline constant thinker

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Re:Separating NaCl
« Reply #6 on: March 23, 2006, 03:26:51 PM »
80°C is a pretty fine line between the melting point of NaCl and the boiling point of Na. Sounds unpleasant, like you said jdurg.
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Offline jdurg

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Re:Separating NaCl
« Reply #7 on: March 23, 2006, 10:41:22 PM »
Yeah, it isn't pleasant at all.  I've been very fortuneate to not have a sodium metal fire break out, but if one does all you can really do is let it burn itself out.  You can't put it out with water, and you can't put it out with CO2.  You need to either smother it, or let it completely combust.  Then you're left with some pretty corrosive combustion products of NaOH and Na2O, or even Na2O2.  The amount of work needed to produce Na from NaCl just isn't worth it when you just want to throw some in some water.  It's much easier to just find a source of it online.  ;D
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Offline billnotgatez

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Re:Separating NaCl
« Reply #8 on: March 24, 2006, 03:53:45 AM »
Does the sodium react with the nitrogen in the air as well?

Offline Alberto_Kravina

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Re:Separating NaCl
« Reply #9 on: March 24, 2006, 08:53:56 AM »
Does the sodium react with the nitrogen in the air as well?
Under high temperature I think that it reacts to a nitride, I don't think that this reaction happens at room temperature, though... :P
« Last Edit: March 24, 2006, 08:54:14 AM by Alberto_Kravina »

Offline billnotgatez

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Re:Separating NaCl
« Reply #10 on: March 24, 2006, 01:01:04 PM »
When you say high temperature do you mean 100C or 1000C?

Offline Alberto_Kravina

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Re:Separating NaCl
« Reply #11 on: March 24, 2006, 01:34:06 PM »
As I said I'm not sure it this reaction even happens, but I think that the required temperature would be between 600-800 0C

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