Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: chiralSPO on 27/04/2021 02:38:11

Title: What would you want to see done with NaK?
Post by: chiralSPO on 27/04/2021 02:38:11
I needed a few grams of some metallic sodium and potassium for my research, but due to the logistics and expense of shipping, it doesn't really make sense to buy less than about 50 grams at a time. So fast forward a little while, and now I have some excess potassium that I need to quench before it goes bad (it can slowly react with oxygen to form a layer of potassium superoxide, which is a very potent oxidizer, and can form explosive mixtures with the mineral oil the potassium is typically stored under).

So I am considering combining the sodium and potassium metals to make the eutectic alloy, which is a liquid at room temperature.It is a beautiful shiny metal like mercury, but tarnishes very quickly if exposed to traces of O2, H2O, or CO2, and will spontaneously combust in the air within seconds to minutes, depending on the humidity and temperature. (don't worry folks, I am trained to work with this stuff, and have a lab equipped with the protective equipment needed to handle the stuff!)

Other than the obvious thing of blowing it up by reacting it with water (which I don't particularly want to do), is there anything that ya'll would particularly like to see a few ounces of shiny liquid metal do on video? Non-destructive and destructive (to just the alloy itself) suggestions will be entertained. I have some ideas myself, but figured I would crowd source a bit before actually making the stuff.

Here are some vids about the stuff that I think are good, but I think I can do better (except for the fountain--I can't do that!!)
fountain: making NaK: (not sure I agree about handling the metals bare-handed, I would probably sweat...)
another synthesis of NaK:
Title: Re: What would you want to see done with NaK?
Post by: Kryptid on 27/04/2021 07:42:34
I've seen a video of mercury dissolving gold, so it would be interesting to see what metals would dissolve in NaK.

Watching how the reaction of NaK with alcohols changes as the number of carbons increase could be interesting. I suspect longer chain alcohols react more slowly than short chain alcohols.
Title: Re: What would you want to see done with NaK?
Post by: CliffordK on 27/04/2021 08:38:52
I was thinking it might be interesting to try to make your own pure sodium/potassium via electrolysis. 

This, however, would also bring up an interesting point.  Is your NaK metal reactive with:  NaCl, KCl, NaOH, or KOH?.

I'd predict that it might be mildly reactive with KCl/KOH, but not reactive with NaCl/NaOH.

Experiment under either mineral oil or inert gas.
Title: Re: What would you want to see done with NaK?
Post by: Bored chemist on 27/04/2021 12:41:14
How hot does it have to be before it attacks glass?
Title: Re: What would you want to see done with NaK?
Post by: chiralSPO on 27/04/2021 14:30:04
I've seen a video of mercury dissolving gold, so it would be interesting to see what metals would dissolve in NaK.
Ahh, interesting! I would not be surprised if there were several metals that could be dissolved by NaK. Gold would be a particularly interesting choice, because it might result in some highly unusual colors (according to a quick literature search, Au4K is "olive green" and Au2K is "violet.")
Title: Re: What would you want to see done with NaK?
Post by: chiralSPO on 27/04/2021 14:34:48
How hot does it have to be before it attacks glass?
The two are compatible indefinitely at ambient temperatures, but would presumably react at elevated temperatures. I once tried to flame dry a flask with Mg chips already in it, and that did the single replacement quite readily! (thankfully tthe reaction was not self-sustaining, and stopped as soon as I removed the heat). I don't think I want to try reacting NaK with its own container (loss of containment might not be safe...), but I might be able to figure something out.
Title: Re: What would you want to see done with NaK?
Post by: CliffordK on 27/04/2021 17:31:36
How hot does it have to be before it attacks glass?
The two are compatible indefinitely at ambient temperatures, but would presumably react at elevated temperatures. I once tried to flame dry a flask with Mg chips already in it, and that did the single replacement quite readily! (thankfully tthe reaction was not self-sustaining, and stopped as soon as I removed the heat). I don't think I want to try reacting NaK with its own container (loss of containment might not be safe...), but I might be able to figure something out.
If you had a heavy wall glass tube,say 1/16" inside diameter with one end closed, put some of your NaK inside under oil, you could mildly heat a couple of drops up.

A mineral oil bath could get you up to a couple hundred C. 

Argon containment might be even better than oil,if you could devise the containment so it wouldn't be be susceptible to pressure.
Title: Re: What would you want to see done with NaK?
Post by: Bored chemist on 27/04/2021 19:07:19
It's reasonable to imagine someone suggesting  mixing NaK with mercury.
That might be interesting, but it might also be more hazardous than people expect.

Title: Re: What would you want to see done with NaK?
Post by: CliffordK on 27/04/2021 20:33:38
It's reasonable to imagine someone suggesting  mixing NaK with mercury.
That might be interesting, but it might also be more hazardous than people expect.

Wonderful video.
I had thought about dental amalgams when you mentioned Mercury.

From reading above, the advantage of the liquid NaK seems to be easily dispersing without an oxidation layer.  So, one would expect the possibility of a vigorous reaction with Mercury.  Although the NaK could be injected subsurface with a small needle such as an insulin needle to limit the quantity instantaneously injected (but doing so constantly to prevent plugging).

The NaK may also rapidly spread into a disc on the Mercury surface.