[Cupro Chlorous]

Yes, I know I can get it for really cheap on the internet, but I tryed making my own.  The result was Bleach.  I used a graphite anode and cathode, and appearanly the chlorine is super reactive with everything.  So, how exactly would i go about separating the anode and cathode?  I read i need a semi permeable membrane.  What should i use?

[Mitch]

Just heat sodium chloride until it melts.

[AWK]

NaOH is produced by electrolysis or by a causticication process (just warming)
Ca(OH)2 + Na2CO3 = CaCO3(s) + 2 NaOH.
It is quite easy to produce NaOH by this way using a small excess of Na2CO3 because
Na2CO3 is sparingly soluble in NaOH

[Cupro Chlorous]

2NaCl + 2H2O ==> Cl2 +2NaOH + H2

Well, I don't want to melt NaCl(not sure how that will help me).  Everything works except for the fact that the chlorine gas realeased in the electrolysis of Aqueous Sodium Chloride reacts with the sodium hydroxide produces to form sodium hypochlorite.  How do i separate them to make this work?

[billnotgatez]

We have discussed the electrolysis of sodium chloride (salt) in hydrogen hydroxide (water) several times here. Usually, the discussion centers on the fact that electrolysis of this solution will not yield sodium. In my opinion that answer is too short. The final result would depend on several factors to include the duration of the electrolysis. Let us assume that the gasses evolved are removed separately from the system as soon as they break the surface of the solution (i.e. vented separately). This would make sure they did not react back with the solution. Then I would expect the reaction to proceed as follows. Initially hydrogen and chlorine would be removed. Then when the chlorine is no longer present the hydrogen and oxygen would be removed until you had solid sodium hydroxide (lye). At this point electrolysis not having a liquid environment would stop. Of course if a special heated electrolysis environment were provided the result could eventually become solid sodium. Again, as mentioned elsewhere, this seems to be a very cumbersome way to get to sodium.

Now what the original poster has added to the mix is something not yet discussed. That is the fact that sodium hypochlorite (bleach) might also be produced. I still think if the duration of the electrolysis were long enough to start producing oxygen, that the chlorine would finally be removed.

My lab experience in this process was long ago, so I can only conjecture. I guess this is why laboratory work is important. Theory is not everything.

Comments?

[Cupro Chlorous]

My intent is NOT to get sodium.  I have the least care in the world for sodium.  My intent is to get some Lye(NaOH).  Since Cl₂ is denser than Air, it is hard to vent.  I will attempt it.

What metals do NOT react with NaOH?  I used a (I Belive) Galvanized iron for the cathode, and it appeared to have reacted with the lye.

Chlorine (being a halogen and all) is just so frickin reactive.  It reacts with the NaOH almost instantly to form NaOCl.

[billnotgatez]

I did not mean for my reply to be a discussion about sodium.

This is a reminder that Chlorine is a poison so watch where and how you vent it.

My main point was to indicate that increasing the duration of the electrolysis might remove the chlorine from the solution, even if it turns into bleach. Sodium hypochlorite is supposed to be unstable. If you run the electrolysis long enough you should eventually run out of chlorine.

from the dictionary - Sodium hypochlorite - An unstable salt, NaOCl, usually stored in solution and used as a fungicide and an oxidizing bleach.

In the past, most people here discussed using carbon electrodes. The systems I have seen used platinum. By the way here is a site that demonstrates the procurement of carbon electrodes.

http://sci-toys.com/scitoys/scitoys/echem/echem.html
The above link is from a site that says
Science Toys You Can Make With Your Kids  

[Cupro Chlorous]

Sorry if I sounded rude in my previous post.  I was getting annoyed.

Maybe if i run it for long enough, all the chlorine would run out...

But i think some of the Chlorine is being absorbed in the brine even before it reaches the surface of the solution.

2NaOCl + 2H₂O -> 2NaOH + Cl₂ + H₂ +

[Cupro Chlorous]

Here is a picture of my setup so far

Tell me if i should change anything.

[billnotgatez]

I am writing some random thoughts. Your experimental report is perplexing.

I just noticed that in your original post you mentioned a semi permeable membrane. I do not recollect ever seeing a semi permeable membrane during electrolysis of brine. Of course, I may have had a sheltered life.

You picture has 3 colors which I assume are not there actually, but represent your theory as to the location of molecules.

Dredging from past memories, it seems to me that chlorine gas smells like bleach.

  http://en.wikipedia.org/wiki/Sodium_hypochlorite  
Based on the previous link, as long as you have the cathode and anode separated, sodium hypochlorite should not form. The other compound sodium chlorate should not form if you keep the electrodes far enough apart as well.
  http://en.wikipedia.org/wiki/Sodium_chlorate  

Again from my memory, the formula for electrolysis of water is as follows.
2H2O = 2H2 + O2
Therefore we get a column of hydrogen twice the size of oxygen.
And again from my memory, the formula for the electrolysis of brine is as follows.
2H2O +2NaCl = H2 +Cl2 + 2NaOH
That produces a column of hydrogen the same size as the column of chlorine.

Remember that according to the link for sodium hypochlorite the following reaction should not occur if the electrodes are far enough apart.
2NaOH + Cl2 = NaCl + NaOCl + H2O

But, I got to believe that some of the hydrogen and some of the chlorine would dissolve in water. The amount is probably small, but it will still give you the smell of bleach. I would think it would eventually dissipate. Maybe if you keep the solution warm but not boiling and the electrodes far apart, then the gases will not stay in solution very well. I still believe that when you use up all of the sodium chloride in the solution and start having oxygen given off because of the electrolysis of the remaining water, that most if not all of the chlorine that was available will be released as a gas.

As always I add the disclaimer. I have not done this in the laboratory and would have to defer to those who actually had some hands on experience. Theorists most always do a lot of hand waving and unfortunately in this case I am not a practitioner. Maybe someone else will weigh in with a link or experience that will be useful.

By the way, I was hoping for the electrolysis of pure water and pure salt to make pure sodium hydroxide would work. One can not always trust the purity of stuff purchased on EBAY. How quickly hopes are dashed.

[Cupro Chlorous]

Thanks alot for all your info!  So if i keep them fairly separated, and just run the electrolysis for long enough, it will produce relatively pure NaOH. I have to be sure to do this outside, to prevent getting Cl₂ vapors in my house.

[billnotgatez]

I would enjoy hearing about your results. Make sure no one is down wind of the chlorine. It is bad enough irritating your housemates, but worse if you irritate your neighbors. They might call the authorities and then we would have to post bail for you.