Electrolysis of Sodium

[Neil9327]

When I was a spotty teenager 20 years ago I was impressed by the experiment at school where a piece of Sodium metal was placed on water, and it caught fire with the released hydrogen, and danced around.

I thought that I would like to make some of my own and that the best material to use for the required electrolysis was sodium hydroxide (caustic soda) which I bought from a hardware store. With the aid of a camping gas stove I was able to melt it in a metal tray (it melts at 300 degrees centigrade or thereabouts), and attach the electrodes of a low voltage DC power supply to start the process. However even at the low voltage it still drew too much current and burned out the fuses.

 

I'm thinking of trying again as I've found the tin of caustic soda in the garage, and have the following questions:

 

1. What voltage is actually required? (I think it was running at 3 volts when I last tried it).

2. A high current is clearly required here. What is the best way to get a low voltage DC high current? Can a unit be purchased from a shop, or can I make my own from purchased diodes etc.

3. Would the sodium produced stick to the electrode, or float to the top of the NaOH? If so would it catch fire?

4. At 100 amps, how long would it take to produce a gram of sodium?

 

Industrially they use mercury to produce it. I have a small bottle of mercury. I might try using it, but it is very toxic and would produce fumes with the heat.

 

FYI I tried to buy some from Aldrich Chemicals but they said no. And that was before the days of global terrorism.

[[w00t]]

I think the method is rather hard to get sodium metal as when the sodium seperates it produces h2o

[jdurg]

At the temperatures required for the electrolysis, the sodium you produce will be in a liquid form. The problem you'll face there is that the liquid sodium will RAPIDLY oxidize and/or react with water vapor in the air. This will result in a very poor yield and the possibility of a fire occuring unless you have a heavy blanket of argon gas over the reaction chamber.

[wpenrose]

1. What voltage is actually required? (I think it was running at 3 volts when I last tried it).

 

2. A high current is clearly required here.

 

3. Would the sodium produced stick to the electrode' date=' or float to the top of the NaOH? If so would it catch fire?

 

4. At 100 amps, how long would it take to produce a gram of sodium?

 

FYI I tried to buy some from Aldrich Chemicals but they said no. And that was before the days of global terrorism.[/quote']

 

The voltage is immaterial, as long as it exceeds the reduction potential of sodium. The best bet is to put a low-value resistor in series with the electrolysis, and increase the voltage until the measured current is just less than the rating of the fuse or circuit breaker. The resistor (a light bulb will do) keeps the current in bounds.

 

As someone mentioned, the sodium will float, but it will be molten, too. You must have a dry, inert gas to blanket it, or you will have sodium oxide instead.

 

Chemical companies will not sell chemicals to private persons, mainly because of the civil liability, and only secondarily because of complications with the DEA and DHS. What that means, is that if Aldrich sells you some sodium and you blind or maim yourself, you'll have lawyers knocking at your door offering to sue the chemical supplier on your behalf.

 

1 amp flowing for one second is one coulomb, or 1/96500 of a mole, of electrons. To convert one gram of sodium ion to sodium metal, with an atomic weight of about 23, will take how many seconds at 100 amps?

 

I forget whether you can use carbon electrodes, or whether you end up with sodium carbide. Try to avoid using mercury if at all possible.

 

Dangerous Bill

[woelen]

This question has been posed many times before. Making sodium at home in a safe and responsible way is almost impossible at home with the limited equipment you have available. You need to work in an inert gas atmosphere (argon, maybe nitrogen also works) and you'll have large difficulties isolating the sodium. As soon as it comes in contact with air, it ignites at a temperature of 300 C.

 

So, I would say, forget about sodium making at home, unless you have really good equipment and can cope with the severe safety issues very well. The average home chemist simply cannot do this.

[jdurg]

If you go to http://www.unitednuclear.com, they actually sell sodium metal pieces so if you truly want some sodium you can purchase it through them.

[Neil9327]

If you go to www.unitednuclear.com[/url'], they actually sell sodium metal pieces so if you truly want some sodium you can purchase it through them.

 

Cool! that's quite something. Unfortunately after entering my order for the Na and K with some magnetic liquid an a small amount of truck bomb mix (ammonium nitrate) (sorry Oklahomians was that in bad taste?) I found that they won't ship outside of the US to the UK

 

Back to the electrolysis. Or maybe I can risk putting some in my hold baggage when I next return from a holiday in Florida...

[Neil9327]

A thought just occurred: In the UK, and I expect also in the US, many streetlights are an orange/yellow which means low pressure sodium lamps. Some others are whiter yellow which are high pressure sodium lamps.

Now if I purchased one of these off ebay (the bulb, not the whole lamppost) and cracked it open with a chissel, would that reveal any metallic sodium?

[woelen]

The lamps use sodium in the gas phase. There is some sodium in these lamps, but it is in microscopic quantities. Not useful for experiments, it would be an insanely expensive source of sodium and you would have to put quite some effort in it to isolate it from the bulb. Before you have done that, it already reacted with humidity and oxygen from the air.

[Hephaestus]

Visit a car wrecker and find yourself some high performance engine valves. Cut each open to reveal several grams of nice, shiny sodium.

 

Be careful!