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Making NaOH

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john bunsenburner

Wed Apr 01 2009, 04:01PM

Registered Member #1937 Joined: Sun Jan 25 2009, 12:28PM
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Posts: 53

and it can be produced from sodium bicarbonate!

I just made a batch of it, i hope it will be ready soon, i also found a bit of it in a test tube of mineand just set up a little apparatus to make hydrogn, pop test sucseeded and i am very content. I noticed that the reaction only takes place when the water is arund 60Â°C or above, when it is below 30Â°C the reaction gets very very slow. At room temperature nothing happened.

hboy007

Fri Apr 03 2009, 01:26PM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
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Chris wrote ...

There are already a few threads on this matter if you do a quick search, which highlight the electrolysis processes.

let me pursue this suggestion a bit further. The process you are looking for is chloralkali electrolysis. If you are having a hard time laying your hands on the materials needed, here is what you do:

1. start collecting old mono cell batteries. (carbon rods) -> this will be your anode (+)
2. buy or find a piece of iron (sanding it will be necessary) -> this will be the cathode (-)
3. build a reactor (PP tubes from the home store should be enough but you can also use acrylic glass if you like. You need two half cells, separated by a membrane, e.g. a piece of an unenamelled flower pot, with gas outlets.
4. get a glass jar with a plastic cover

now here comes the fun part: the products of chloralkali electrolysis are chlorine gas, hydrogen gas and sodium hydroxide solution. Now you can burn the emerging gasses in the jar and wash them with water and you end up with hydrochloric acid and sodium hydroxide brine.

The only problem is, you might find heating and degassing the sodium hydroxide solution necessary because chlorine dissociates to chloride and hypochlorite when it reacts with concentrated brine.

If you need high-purity chemicals, building an induction heater and electrolysing molten sodium chloride is the way to go (I have been dreaming of that for a long time now

). You have to stay within 810..870Â°C and there you go: liquid sodium metal. From that point on, it's not that hard, is it?

PanosB_GR

Fri Apr 03 2009, 04:42PM

Registered Member #1680 Joined: Fri Sept 05 2008, 04:19PM
Location: Greece
Posts: 43

Here (GR), anhydrous NaOH (like 95% pure) can be found in markets for unclogging drain pipes and kitchen sinks! And it is ridiculously cheap!

john bunsenburner

Fri Apr 03 2009, 09:18PM

Registered Member #1937 Joined: Sun Jan 25 2009, 12:28PM
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Posts: 53

Greatly informative post hboy. I found that using sodium carbonate gives me desired effects and so i am content. As a little recomendation fo you: If you want to do electrolosis on molten sodium chloride add calcium chloride thsi lowers the melting point to around 700Â°C. And i read some where that once NaCl and CaCl2 are molten and the correct electric source is used then the mixture needs no further heating, the electricity exerts eanoth heat(most probably the mixture has high resistance) to keep the temperature around 700Â°C.

asimov13647

Sat Apr 04 2009, 02:08PM

Registered Member #2048 Joined: Wed Mar 25 2009, 08:58PM
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Why is NaOH so difficult to obtain in Switzerland? Don't the Swiss make soap? I found a one kilo container of pure NaOH at the local Tractor Supply for $10. Then I discovered a website that sold the same item for half the price. Even so, you may find NaOH at an auto mechanic's shop where it is used to degrease engine parts. I can't think of any "safe" non-organic alternative to NaOH as a degreasing agent.

john bunsenburner

Sat Apr 04 2009, 03:26PM

Registered Member #1937 Joined: Sun Jan 25 2009, 12:28PM
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Posts: 53

It does exist, just that no person will sell it to me. Chances are that you would need some license, i do have one but only for buying things in a chemistry supply store so that everythign is very pure and very expensive. Most other places will simply not sell it to me.

hboy007

Sun Apr 05 2009, 08:11AM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
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Posts: 374

Thanks, john bunsenburner.
Indeed, eutektics such as soda/potash or soda with other fluxing agents are a good way to start. I would have to look up what exact voltage is needed to achieve good results. Unfortunately, there will be a good chance that concentrations vary over time and potassium or calcium will be deposited as well. What we would be ending up with is a sodium potassium alloy which is great fun because it is highly reactive. I'm going for pure sodium metal, unfortunately soda itself won't melt at a lower point then sodium chloride, even at an about 40K higher temperature.

The self-sustaining heat source is a pretty elegant way, though. Thanks for the tip, I'll surely try that if the necessary current density matches.

Bored Chemist

Sun Apr 05 2009, 09:03AM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Hang on a minute.
Electrolysis of fused salts is a lot of touble. John, I don't know exactly where you live but I wonder if nipping across the border to the EU where NaOH is for sale might be easier than trying to make it.
Ordering it from eBay and hoping that customs let it through is another option.
Even electrolysis of NaCl with a mercury cathode then reacting sodium amalgam with water seens a safer bet than the molten salt.

john bunsenburner

Sun Apr 05 2009, 07:51PM

Registered Member #1937 Joined: Sun Jan 25 2009, 12:28PM
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Posts: 53

Dont worry I will not go through the trouble of makign sodium metal and then NaOH from that, it was another, unrelated matter which we discussed. I am fairly far away from the border and i really cannot be bothered using ebay. For now sodium carbonate fulfills my needs, and if i do need sodium hydroxide then i will use the expensive, pure, sodium hydroxide.

hboy007

Sun Apr 05 2009, 10:54PM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
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Posts: 374

Bored Chemist wrote ...

Electrolysis of fused salts is a lot of touble.

Apart from soaked crucibles, what else is there? I intend to stay near the melting point. Things like molten sodium and chlorines gas are far more worrying, aren't they? Will liquid sodium form an amalgam with an iron electrode?

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