[Scratch-]

Hello! I have been away from the forums for awhile but I'm back! I really do enjoy chatting about chemistry with you guys, and I have a neat experiment here I would like to try it. I have alredy talked to Limpet Chicken about this and he thinks it would be a neat thing to try. Heres what I'm going to do...

Need:
Argon (Welding shops)
Crucible stand
Oxygen/acetylene torch
Goggles
Gloves
Apron
Test tube
Metal spoon
Carbon electrodes (You can get them from carbon-zinc batteries)
Car battery
Wire
Sodium chloride (Sea salt or rock salt)
Potassium chloride (No-salt)
Crucible (Or crack proof ceramic container)
Dish
Large airtight container with the top open (For doing things under argon)


Procedure:
1. Purify the sodium chloride and potassium chloride
   A. Dissolve the salts in water in separate containers
   B. Filter with activated charcoal trapped between cotton
   C. Let set for a few days and pipette off the top until you are almost going to disturb the bottom
   D. Evaporate slowly and let crystallize
   E. Take perfect crystals and dissolve again
   F. Re-crystallize and take out perfect crystals again
2. Electrolyses NaCl and KCl in separate containers to make the hydroxides
3. Dry hydroxides with gentle heat
4. Put on goggles, gloves and apron
5. Heat the top neck of a test tube and almost seal it
6. If step 2 doesn't work then get ampoules
7. Drill a small hole (1-2mm) in a metal spoon
8. Prepare the car battery and electrodes
9. Place crucible on its stand
10. Heat crucible gently to drive off moisture
11. Put sodium hydroxide in the crucible and heat gently to drive off moisture
12. Before hydroxide cools pour argon into crucible
13. Heat crucible until hydroxide melts
14. Insert electrodes and apply electricity
15. Continue heating hydroxide until a generous amount of sodium forms
16. Immediately take out sodium and cool under argon, store in mineral oil
17. Repeat steps 7 to 15 for the potassium hydroxide
18. Heat the test tube to drive of moisture, put under argon
19. Put 60 percent potassium and 40 percent sodium in the crucible under argon
20. Heat until both are melted together well
21. Pour mixture through the spoon into the test tube until about half full
22. Put the rest of the mixture in a container under argon
23. Heat the neck of the test tube and close the end
24. Smooth out the neck of the test tube
25. Clean up apparatus and enjoy one ampoule of NaK alloy!

What do you think? NaK is liquid at room temperature and is probably more reactive than sodium or potassium because its liquid. I'm thinking of using something other than a car battery though, maybe an AC adapter.

[Donaldson Tan]

your mean to isolate NaK in argon sounds dodgy... moreover, u have to remove oxygen inside your argon container and a really dry environment to carry out your experiment.

[Scratch-]

I know that people have made sodium and potassium with electrolysis of the molten hydroxide (Even without argon). It may be partially oxidised by the time I get it into the ampoule but I dont know.

Do they add oxygen to those argon wielding bottles? I thought they just did that with helium baloon bottles. Its true that where I live is very humid, is there anything I can do besides doing this under argon and heating things do drive off heat? (I might be able to do this on a very cold day or something)

EDIT: I talked to Limpet Chicken again about getting oxygenless argon and he says that I can get it at the welding stores too.

[jdurg]

NaK alloy is fun, but hazardous, stuff.  It's a neat little liquid at room temperature, and if you have it in a test-tube the top part of it will oxidize readily and form a 'crust' on it while the other stuff stays bright and shiney.  It is a bit more reactive than either sodium or potassium alone, although I'd say that it's more along the lines of potassium in terms of reactivity.  I made some a while back using some potassium and sodium metal which I melted in a closed container filled with argon gas.  (As both Na and K have low melting points, simply putting the two into a small, sealed, vial with Ar and heating it over a hot stovetop easily melted it.  The stuff is neat to play with.  hehe.  (I really shouldn't say 'play'.  It's more along the lines of 'experiment').  I took my mL or so of it and just spread it out on slate.  It VERY quickly oxidized, and soon caught fire.  Once it catches fire, you're done.  It really will not go out.  So I stood WAAAAAY back and fired a garden hose at it.  Let's just say there was a nice 'pop' and the stuff was gone.  

[Scratch-]

The only problem with melting it in the ampoule is that I pour it through a small hole to get rid of any oxides or hydroxides left in it. But I'll definatly keep a little vial of it in an openable container to, uhm, experiment with.  

[limpet chicken]

Jdurg, how quickly did your NaK alloy take fire? I plan on making maybe a few 100g or so, by electrolysis, would you say its intermediate between K and Rb in reactivity?

Scratch got me interested in this stuff, so I'm going to try it  

Jdurg, not that I want to waste NaK on making it explode, but roughly how powerfully did that few ml or so explode, on contact with water?

[jdurg]

When I first opened up the container, the NaK quickly oxidized on the top.  When I poured it out, it kind of stayed in a little area for a while and developed the oxidized 'crust'.  As that concentrated blob flattened out and increased its surface area, it began to ignite.  So I'd say it was a good 5-7 seconds.  

The 'pop' was akin to having a small potassium chunk in water.  I would not put it anywhere near rubidium in terms of reactivity, but more like potassium in most regards.  It's just that being a liquid makes it more prone to react.  However I'd have to say that five grams of it would react like 6 or 7 grams of pure potassium.

Also, it's not very dense at all so 100 grams would be a LOT of it.  

[Scratch-]

Interesting, maybe we should have a NaK party.