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Molecular Manipulations
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Inert gas is easy. You can even use a helium balloon if you can't get nitrogen.
To generate nitrogen, drop a hot solution of sodium nitrite in pressure equalized addition funnel onto warm ammonium chloride, nitrate, sulfate or any
common salt. It's best to dry the gas by bubbling it through concentrated sulfuric acid, which will also get rid of ammonia impurities.
-The manipulator
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deltaH
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Also, this flame that burns briefly on the sodium, it just occurred to me that it might be a small amount of residual paraffin used to shield the
sodium from oxidising. Simply dabbing the sodium on some filter paper is not going to remove the film of oil clinging to it.
To test this hypothesis, I suggest dipping the tiny piece of sodium in some ethanol with tongs, then waiting for the ethanol to evaporate when pulled
out before putting the sodium bead on water.
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blogfast25
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Quote: Originally posted by deltaH  | Also, this flame that burns briefly on the sodium, it just occurred to me that it might be a small amount of residual paraffin used to shield the
sodium from oxidising. Simply dabbing the sodium on some filter paper is not going to remove the film of oil clinging to it.
To test this hypothesis, I suggest dipping the tiny piece of sodium in some ethanol with tongs, then waiting for the ethanol to evaporate when pulled
out before putting the sodium bead on water. |
If you clean up the outside of your piece of sodium, then cut out a cubic (e.g.) piece from that, then you are working essentially oil free.
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Morgan
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One time I put about 50 grams of sodium in a jar with rocks to weight it down and a few holes punched in the lid. The jar sank to the bottom of the
backwater slough I had previously been exploding sodium on the surface of the water. The jar bubbled for a seemingly long time but didn't crack or do
anything fun like I thought it would because of the lack of oxygen. I was only 15 at the time and didn't quite grasp what would happen.
The pieces that I threw on the surface however exploded in such a way as to propagate a machine gun jungle warfare sound when a tossed single hunk of
metal became molten and subdivided into several pieces after the first explosion. My friend who was with me couldn't stop talking about it to his
friends later. It was fun I have to admit.
Anyway would a piece of sodium held underwater in some sort of quartz glass chamber be anything to study as it melted but didn't explode? It could
bubble away but not take fire. Of course this would upset the conditions that occur in air but maybe it would provide some insight of how the
byproducts behave if enough heat were generated. I guess it would be about the same as using an inert atmosphere except the "air" or "inert gas" would
be hydrogen.
The electrostatic properties would be fun to harness if you could use sodium in this way to generate a very large spark somehow for a demonstration.
[Edited on 7-3-2015 by Morgan]
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Sulaiman
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I suspect that a hydrogen atmosphere would cause NaH to be produced,
even nitrogen can form Na3N but as it decomposes above 87C I'm unsure of the result.
Sodium is really reactive!
I've been looking for a denser-than-air gas, or a liquid less dense than sodium
that is easily available and doesn't react with molten sodium or NaOH .
argon is the best so far but I'm still looking
meanwhile found a few relevant YouTube videos.
I like this one https://www.youtube.com/watch?v=BIGMfai_ICg
Also, been doing a few sums;
1g of sodium has about 4197 Coulombs available
maybe enough to form a plasma or sparks beneath the sodium?
the sodium ball is obviously above it's melting point of 97.8C
and below it's boiling point of 883C
hydrogen spontaneously ignites in air above 500C so it could be that simple
or it could be electrical ignition?
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Molecular Manipulations
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No it can't. Just because it doesn't decompose readily at STP doesn't mean it can form at STP.
| Quote: | Originally posted on Wikipedia
Sodium nitrite can be generated by combining atomic beams of sodium and nitrogen deposited onto a low-temperature sapphire substrate.
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Doesn't sound like something that's going to form anywhere near water or at high temperatures.
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Sulaiman
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OK, thanks for clarifying that, my mistake.
Regarding the first YouTube video on transparent sodium that I watched
https://www.youtube.com/watch?v=DJGVZNth68k
there is an interesting similarity to part of the Wikipedia article on sodium
"Sodium at standard temperature and pressure is a soft silvery metal, that oxidizes to grayish white unless immersed in oil or inert gas. Sodium can
be readily cut with a knife, and is a good conductor of electricity. These properties change dramatically at elevated pressures: at 1.5 Mbar, the
color changes from silvery metallic to black; at 1.9 Mbar the material becomes transparent, with a red color; and at 3 Mbar sodium is a clear and
transparent solid"
just coincidence?
P.S. can anyone suggest a transparent liquid less dense than and un-reactive with sodium?
GOT IT ... simple hydrocarbons like kerosene.
P.P.S. checked with my son, no high speed video capture available.
[Edited on 6-3-2015 by Sulaiman]
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420MLGnOhEADsCOPEpro
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i agree with deltaH about the transparent end product being NaOH with Na2O dissolved in it
judging by the color of radiated light it never gets much hotter than 500C so we can rule out boiling Na 883C NaOH 1388C Na2O 1950C or molten Na2O
1132C
thus i conclude that the explosion of the transparent droplet must be caused by water
i assume it's something like this
water is pulled into the droplet where it reacts with Na2O
water that rushes into the droplet increases the temperature, decreases the boiling point of dissolved water, decreasing the surface tension and
increasing the mass of the droplet
after some amount of time one of two things happens
some of the water boils causing the droplet to break
or the increased temperature and water content reduces the surface tension enough that the droplet breaks
then the hot NaOH solution hits the water causing it to boil
thus explosion
i think that in an inert atmosphere the Na would react with NaOH to form Na2O and H2 thus producing a similar result to when in air
the droplet can't be sodium because it's not reflective
as far as i'm aware a transparent metal is effectively a contradiction as a metallic bond is reflective by nature
metals can be transparent if they are thin enough though but that's confusing quantum mechanics stuff that can't be scaled up
so it can't be transparent metal (as the droplet is more than a few hundred nanometers thick)
sodium can be transparent however this is in one of it's electride states and requires a pressure of 3 Mbar
so it can't be an electride because the droplet surely wasn't under that kind of pressure (however there may have been small amounts of electride
sodium produced by internal voltage gradients while the was still metallic sodium but this more resembles sodium ions stuck to an electrode in an
electrolytic capacitor than electride ions and there lots of weird properties of such ions so it's hardly anything like an electride)
also for anybody wondering about reflection
metals are reflective because metallic bonds are basically pools of free floating electrons
when that pool of electrons is struck by a photon it matches the oscillations of the electric field and thus absorbs and re-emits it
molten salts can't do this because all the electrons are bound to an atom
though i think molten salts can reflect radiowaves and microwaves because
this is because radiowaves and microwaves are huge compared to visible light and thus the ions can match the field enough to absorb and re-emit them
however there are some big differences between reflection of visible light and microwaves and radiowaves
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Molecular Manipulations
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| Quote: Originally posted by 420MLGnOhEADsCOPEpro |
[...]the droplet can't be sodium because it's not reflective
as far as i'm aware a transparent metal is effectively a contradiction as a metallic bond is reflective by nature
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That's where coulombic explosion comes in:
| Quote: Originally posted by Molecular Manipulations | | reflective sodium comes from only the outer valance electron, once removed it becomes a colorless, non-reflective ion. It seems likely that ionized
sodium, by itself would be colorless. |
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m1tanker78
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The strange thing is that when sodium burns in air, it forms a white coral-like structure that turns yellowish (sodium peroxide) when it cools
sufficiently. There is a period when it turns black, before it goes white IIRC. In the video, I didn't see any such formation. I still say steam plays
a major role.
I still don't see a strong case for using an inert atmosphere. I still see a case for burning a piece of sodium in steam... Unless I'm missing
something?
If the events in the video line up with my observations from when I started messing around with a Downs cell design then the reaction can be quenched
with mineral oil at any stage. I pulled some translucent beads as well as some red beads. The explanation for the red beads at the time was that the
oxide layer was creating an interference pattern or something like that. I don't buy it.
I'm giving some thought to how NOT to destroy my camera and still get the shot before I roll up my sleeves and play ball.
Chemical CURIOSITY KILLED THE CATalyst.
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j_sum1
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The reason for the inert atmosphere is to try to eliminate any reaction between Na and air. This simplifies things a bit and enables one to observe
the reaction with water without a flame getting in the way.
Argon is available at welders' supplies. You can also buy a can at a wine shop. Helium might be your cheapest inert gas if you onky want a small
amount but you will need to contain it since it is so light. A bell jar or glass bowl might work.
I expressed doubt on Na2O being produced because its MP is sohigh and we clearly have a melt. It is possible that it is a solution of some Na2O in
NaOH. But I haven't checked a phase diagram and I am not sure what temps we are talking about here. I doubt there is a sphere of molten NaOH reacting
on the inside with its metallic skin. Where would the H2 go?
I also thought the bead might contain some water. This would mean that it doesn't contain the oxide.
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Eddygp
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Maybe some sort of molten sodium + molten sodium oxide + molten sodium hydroxide... think about how the filter paper does not allow water to join the
blob immediately. The explosion suggests that it has not reacted completely, so it cannot be pure sodium hydroxide. My guess would be either a
Coulombic explosion or some sort of solution of sodium and sodium oxide in molten something.
there may be bugs in gfind
[ˌɛdidʒiˈpiː] IPA pronunciation for my Username |
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Morgan
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Maybe it would be interesting to try some coin shaped disks to offer more surface area if a coulombic effect is taking place. Although the smaller
sodium pieces once melted take on a somewhat spherical shape, there might be something to elicit in the first second or so when initial contact with
the water is made, dumping more charge more suddenly with intimate contact. Or maybe not.
[Edited on 7-3-2015 by Morgan]
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Molecular Manipulations
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Eddygp, that's not a bad theory. But theres one problem. I know molten sodium hydroxide about 60 deg. above it's melting point will
dissolve sodium, per experience with a caster cell. But I always thought it was an irreversible reaction, not just a regular solvent-solute solution,
but rather the hydroxide ion oxidized the sodium and reduced hydrogen to elemental. I highly doubt sodium wouldn't reduce hydroxide in such a
situation.
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We are all here on earth to help others; what on earth the others are here for I don't know. -W. H. Auden
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m1tanker78
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Morgan - sodium 'tortillas' tend to break up into multiple spheres.
j_sum - Might be worth a try if nothing else, to have a reference. There shouldn't be a flame but there will be steam.
eddy - Did you ever observe the hydride salt in the leftovers of the Castner cell? I would regularly encounter it when dissecting the cooled salt
block of a Downs cell when sodium bicarbonate was added to the melt.
Could we make a spreadsheet with all possible elements, molecules and transitional species in this scheme on X and Y and figure the HOF of each for
reference?
How about a RBF 1/3 filled with water, Ar purge and gentle flow, film from below and hope to have a little magnification and clear sight up through
the apparatus? There shouldn't be any explosion or other RBF-destroying events.....right?? The phone/camera should survive too...??
Anybody have an underwater camera or one of those water proof cell phones? 
Chemical CURIOSITY KILLED THE CATalyst.
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Sulaiman
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My five individually sealed 28g sodium ingots arrived today
but I have not made all of the safety preparations for experimenting yet
meanwhile, could someone check these calculations for me as the results are surprising;
1 mole = 23g = 6.022 x 10^23 atoms/ions = (6.022 x 10^23) / (6.241 x 10^18) = 96500 Coulomb
So 1g of sodium reacting in 10 seconds = 96500 / (28 x 10) = about 420 Amps average !
This would mean;
phenomenal I^2 x R heating
and
if the molten bead is at times supported by the Leidenfrost effect then
there could be a huge voltage difference between the sodium and the water due to
dV = dQ/C where C (capacitance) would be very small. (V=voltage, Q=charge)
This is why I want to try to view the voltage difference on my oscilloscope.
I have a high voltage, high frequency probe that will add 100 MOhm plus 3pF to 5 pF 'load'
so results may be affected by the probe but I should get an indication of the effect.
I still have no idea how to attach the probe,
I have no platinum wire so I will first try very thin copper wire and (hopefully) progress from there.
I also want to 'collect' the transparent bead for analysis,
I suspect (for no scientifically researched reason, just a guess) that there is massive surface tension on the bead,
so touching it may cause instant detonation (to be determined)
so i'm thinking of using a puff of air to blow the transparent bead on to a ceramic tile.
Any better/other ideas welcome.
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Sulaiman
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Couldn't edit my last post, hope double post is ok.
Unpacked one of the 28g sodium ingots today,
only a fraction of a millimeter surface corrosion found.
I cut it up to fit under (Johnsons baby) oil in a small container.
Good news;
I found it very easy to repeatedly produce 'transparent sodium' spheres in a quick test.
Bad news;
whilst setting up I broke the head off of my camera tripod 
and I did not want to try cutting up the sodium or experimenting with one hand holding the camera.
so no video yet.
Safety procedures for collecting the spheres and electronic measurements not ready yet.
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Kitsune1
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Very interesting Sulaiman, I look forward to hearing more about your experimentations with this.
I have a thought on this subject that I don't think anyone has yet touched on yet, how would an identical reaction take place with Li or K in place of
Na? would a similar reaction be possible? How would the rate of reaction vary between the group 1 metals?
As has been pointed out previously, the leidenfrost effect certainly seems plausible to be at least one part of what is going on here.
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morganbw
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| Quote: Originally posted by Sulaiman | Couldn't edit my last post, hope double post is ok.
Unpacked one of the 28g sodium ingots today,
only a fraction of a millimeter surface corrosion found.
I cut it up to fit under (Johnsons baby) oil in a small container.
Good news;
I found it very easy to repeatedly produce 'transparent sodium' spheres in a quick test.
Bad news;
whilst setting up I broke the head off of my camera tripod
and I did not want to try cutting up the sodium or experimenting with one hand holding the camera.
so no video yet.
Safety procedures for collecting the spheres and electronic measurements not ready yet. |
That it is repeatable is great.
It actually made me smile.
Collecting the spheres may be a serious task.
[Edited on 11-3-2015 by morganbw]
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j_sum1
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| Quote: Originally posted by Kitsune1 | | I have a thought on this subject that I don't think anyone has yet touched on yet, how would an identical reaction take place with Li or K in place of
Na? would a similar reaction be possible? |
I reported on an experiment with K upthread. No Li done yet.
I have given considerable thought to a mechanism nd can account for most observations. However, reporting this will take some time that I don't have
at the moment. Watch this space.
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Sulaiman
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| Quote: Originally posted by Kitsune1 | Very interesting Sulaiman, I look forward to hearing more about your experimentations with this.
I have a thought on this subject that I don't think anyone has yet touched on yet, how would an identical reaction take place with Li or K in place of
Na? would a similar reaction be possible? How would the rate of reaction vary between the group 1 metals?
As has been pointed out previously, the leidenfrost effect certainly seems plausible to be at least one part of what is going on here.
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A similar effect has been observed using sodium/potassium amalgam (liquid at room temperature)
during research into the mechanism proposed for the sudden violent explosions ... 'coulombic explosion'
excellent video
https://www.youtube.com/watch?v=LmlAYnFF_s8
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420MLGnOhEADsCOPEpro
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i just noticed something after watching https://www.youtube.com/watch?v=BIGMfai_ICg
he says that the droplet is a dark blue not black in this video (which seems to show the same reaction as is in question here)
i was wondering why the droplet was so dark before becoming transparent and then i remembered that alkali metals dissolved in ammonia are blue
https://en.wikipedia.org/wiki/Electride
this video shows that it's about the same dark blue we're seeing
https://www.youtube.com/watch?v=JefumJFatsw
i think this is strong evidence that an electride state is present at least while it's blue
is it possible this is [Na(H2O)x]+ e- (i don't know what x would be)
i find it unlikely that [Na(H2O)x]+ e- is the electride though when i heard about electrides i though it was odd that the ammonia doesn't react into
Na+ NH2- (wikipedia says that this happens slowly but i don't get why)
this is definitely relevant to the composition and it gives me an idea as to how it might explode
consider that it's sodium with some amount of hydroxide OH-, some amount of hydride H- and some amount of oxide O-2 dissolved in it that allows it to
take on an electride structure
i theorize this is possible considering if there are sodium ions Na+ in the sodium metal then they would often trade places and at some concentration
would be more stable in the electride phase where no electron swapping is required to switch places relative to the anions
this should prevent a columbic explosion by allowing some flow of electrons to the Na+ that is reacting with the water
if for whatever reason the sodium was no longer an electride it would explode as it usually does
this may be occurring at the surface of the sodium that is reacting with the water due to a change in ion concentration or temperature
edit i think you could test if it's an electride by holding a strong magnet next to it
so if anybody is going to test it and has a rare earth magnet lying around i'd suggest taping it to a stick and waving it by the drop at various
points during the experiment
[Edited on 12-3-2015 by 420MLGnOhEADsCOPEpro]
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morganbw
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| Quote: Originally posted by Sulaiman | | Quote: Originally posted by Kitsune1 | Very interesting Sulaiman, I look forward to hearing more about your experimentations with this.
I have a thought on this subject that I don't think anyone has yet touched on yet, how would an identical reaction take place with Li or K in place of
Na? would a similar reaction be possible? How would the rate of reaction vary between the group 1 metals?
As has been pointed out previously, the leidenfrost effect certainly seems plausible to be at least one part of what is going on here.
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A similar effect has been observed using sodium/potassium amalgam (liquid at room temperature)
during research into the mechanism proposed for the sudden violent explosions ... 'coulombic explosion'
excellent video
https://www.youtube.com/watch?v=LmlAYnFF_s8 |
I was reluctant to watch the video because of its length but I am glad that I did.
Thank you for the link
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Kitsune1
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| Quote: Originally posted by j_sum1 |
I reported on an experiment with K upthread. No Li done yet.
I have given considerable thought to a mechanism nd can account for most observations. However, reporting this will take some time that I don't have
at the moment. Watch this space. |
I happen to have some Lithium left over from a few months back which should be ideal for trying this out with. Hopefully I'll be able to find some
time tomorrow to do a few runs, will report back once done.
Really interesting video, a bit on the long side but the content does justify it.
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Wizzard
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Perhaps a light source with a special spectral characteristic to differentiate molten NaOH, molten NaO and molten Na?
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