Sciencemadness Discussion Board

"invisible metal"

HeYBrO - 22-4-2014 at 22:56

Has anyone seen this video? NaK reacts and becomes transparent (clear). https://www.youtube.com/watch?v=BIGMfai_ICg
Thoughts?

[Edited on 23-4-2014 by HeYBrO]

deltaH - 23-4-2014 at 03:21

Leidenfrost effect on a drop of molten sodium/potassium hydroxide?

Also, sodium and potassium hydroxide form a eutectic:
Quote:
The eutectic mixture of 59 weight percent potassium hydroxide (KOH) and 41 weight percent sodium hydroxide (NaOH) is effective. The KOH—NaOH eutectic mixture has a melting point less than either of its constituent hydroxides. The KOH—NaOH eutectic mixture melts at 170° C. compared with 318° C. for pure NaOH and 360° C. for pure KOH.


From http://www.google.com/patents/US20050072837

So my best speculative guess is the NaK produces a very hot molten drop of hydroxides that has a low melting point. It stays suspended above the water because of the Leidenfrost effect while it's still extremely hot, but at some point, water is no longer boiled beneath it and at that point it mixes effectively and dissolves instantaneously, aka... 'explodes'.

[Edited on 23-4-2014 by deltaH]

Zyklon-A - 23-4-2014 at 06:00

Why don't people electrolyze this eutectic mixture? I'm not sure how they might seperate the resulting mixture of alkalis, but I'm sure it's possible. Even if its too hard, I would like the mixture itself.

deltaH - 23-4-2014 at 10:28

I've been wondering that myself ever since I read about the electrolysis of molten sodium hydroxide on SM. Also, one may not even want/need to seperate the sodium and potassium in NaK for many applications no?

Why don't you start a new thread for that?

Zyklon-A - 23-4-2014 at 11:08

Well, maybe, I have no potassium hydroxide, and no refs at the moment. It would have to be in beginnings unless I find some more info...

Etaoin Shrdlu - 23-4-2014 at 13:34

There are thousands of refs on the electrolysis of alkali hydroxides, and you have one for the properties of that mixture of interest just above...what's the problem?

EDIT: Never mind, I see it's up.

[Edited on 4-23-2014 by Etaoin Shrdlu]

nezza - 27-4-2014 at 10:03

I have observed a clear ball floating on top of the water after sodium or potassium have reacted with it. I suspect it is a liquid/molten blob of hydroxide/oxide of the alkali metal, not the metal itself as it starts out red hot and cools, finally reacting explosively with the water.

BobD1001 - 27-4-2014 at 10:18

Wow, that's is truly amazing!

zed - 27-4-2014 at 15:24

Clear?....Shoot a beam of light through it, and study spectra.

Also, when are we going to see some transparent Aluminum? Don't be shy! If you have secretly developed a technique for producing transparent Aluminum...... share. I know you are all very humble, and you don't wish to draw attention to yourselves, but share a little bit. We are interested!

nezza - 28-4-2014 at 11:01

Video of sodium reacting with water leaving red-hot ball of oxide? on surface.

Attachment: My Movie2.mp4 (1018kB)
This file has been downloaded 412 times

Etaoin Shrdlu - 28-4-2014 at 14:26

Quote: Originally posted by zed  
Also, when are we going to see some transparent Aluminum?

Surely you jest.

LanthanumK - 30-4-2014 at 14:52

I lit a piece of lithium on fire once and dropped it into water. It reacted in a similar manner to sodium metal, but after the metal was done reacting, a red hot blob of oxide did float on the surface of the water. The resolution was not high enough to see if a clear blob of solid was left behind.

Re: surface tension. Iron filings easily float on water and they are 7 times heavier. In fact it can be impossible to get them to sink. Surely a small amount of fused NaOH can float for a short time.

HeYBrO - 30-4-2014 at 22:32

Nezza you should sent that the poster of the video! I'm sure he would be thrilled to see that it can be replicated. Do a video response!

vmelkon - 7-5-2014 at 13:29

Quote: Originally posted by deltaH  
Leidenfrost effect on a drop of molten sodium/potassium hydroxide?

Also, sodium and potassium hydroxide form a eutectic:

Quote:
The eutectic mixture of 59 weight percent potassium hydroxide (KOH) and 41 weight percent sodium hydroxide (NaOH) is effective. The KOH—NaOH eutectic mixture has a melting point less than either of its constituent hydroxides. The KOH—NaOH eutectic mixture melts at 170° C. compared with 318° C. for pure NaOH and 360° C. for pure KOH.


From http://www.google.com/patents/US20050072837

So my best speculative guess is the NaK produces a very hot molten drop of hydroxides that has a low melting point. It stays suspended above the water because of the Leidenfrost effect while it's still extremely hot, but at some point, water is no longer boiled beneath it and at that point it mixes effectively and dissolves instantaneously, aka... 'explodes'.

[Edited on 23-4-2014 by deltaH]



Like you said, it could be that it produces hydroxide, which would be molten. My guess is that the NaK dissolves in the hydroxide to give a dark blue color. Once no more metal is present, it looks transparent. As it cools, it drops into the water but perhaps it is still above 100 oC and so it blows up the water.

However, like the video says, the density of of NaOH and KOH is about 2x that of water. I don't know about liquid NaOH and KOH mixture.

He needs to capture that ball before it falls into the water and let it cool off.

[Edited on 7-5-2014 by vmelkon]