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blogfast25
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No and it's an accident waiting to happen: molten NaOH reacts almost violently with aluminium. To spice things up, you've got a
strong oxidiser in there: NaNO3!
NaOH + 2/3 Al --- > Na + 1/3 Al2O3 + 1/2 H2
NaNO3 + 2 Al --- > Na + 1/2 N2 + Al2O3.
Check out the standard heat of formation of Al2O3 to predict end result! 
[Edited on 30-4-2011 by blogfast25]
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cyanureeves
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blogfast25 i wont do it then. besides i saw flames when some of the sodium popped at the anode and i dont like the toxic fumes tanker talked about
either.
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blogfast25
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Yes, stay well clear: molten caustic soda is dangerous enough, w/o Al or nitrate in the mix...
Try providing an argon blanket: use welding gas (but not Ar/CO2 mix!) and get a gentle flux to cover the surface of the melt and electrodes. Depriving
sodium of air oxygen prevents it from oxidising...
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m1tanker78
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91% IPA Experiment Update:
All of the remaining IPA has evaporated, leaving only the bottom aqueous(?) layer. It has the strong, skunky odor of the heavy oil I used to melt the
sodium nugget prior to the experiment. I suppose that accounts for the yellow color I observed at the bottom. In spite of practically scrubbing the
nugget with a paper towel, a little bit of the oil still stuck to it! This is the final nail in the coffin of the heavy oil I experimented with. Good
riddance!
Tom
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blogfast25
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For storage, a clean, clear kerosene or unadulterated paraffin oil is really the best with both Na and K.
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m1tanker78
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I was digging around in the can where I kept the original junk from the cinder block/chrome GT and came across another unusual find. I removed a few
'sodium' beads and placed them in clean(er) mineral oil. Some of the beads retained a red tint in various shades. Purple sodium (original post) was
weird enough but red?
Ascending intensity of red beginning at the 12 o'clock position with 4 o'clock being the most intense...
Has anyone here seen sodium superoxide (NaO2) up close? I'm not saying that these beads are covered with NaO2. I'm curious about the claims of it
being "yellow-orange". I've never seen any practical references for it and I can't find a single 'real life' image for it.
Tank
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m1tanker78
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I made another sodium nugget only this time, I didn't contaminate the bath with anything so the new nugget is as close to 100% Na as it gets. For
coalescing, I used approximately the same volume of oil and heated approximately to the same temperature and length of time as I did for the prior
nugget in question. Upon cooling, I was surprised to see the surface slowly change from a mirror finish to a semi-matte violet then bluish violet. I
suspect that after a day or two, it'll settle at silvery-white like the original.
New sodium nugget at forefront, prior questionable nugget just behind on the left...
ASSUMPTIONS: The higher heat and longer length of heating caused the sodium metal to 'anneal' which sort of explains the weird
colors and above all, the unusual crystallization patterns in the cross section. BlogFast nailed it but I wanted to find out specifically what oxides
and why. I'm still puzzled with the red colored sodium in my previous post. Seems like a large disparity in light diffraction to only be one compound.
So far, I've seen plenty of bluish coloring and not so much red. The spectral extremes seem to be blue and red. A fine dispersion of the two will
obviously appear to be violet/purple in differing shades which I've also seen. For now, I can only assume that the blue hue is seen because of sodium
oxide and the red hue is possibly sodium superoxide. Sodium peroxide is light yellow; a pretty well known fact and one I've seen myself.
Tank
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blogfast25
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Quote: Originally posted by m1tanker78  | BlogFast nailed it but I wanted to find out specifically what oxides and why. I'm still puzzled with the red colored sodium in my previous post. Seems
like a large disparity in light diffraction to only be one compound.
So far, I've seen plenty of bluish coloring and not so much red. The spectral extremes seem to be blue and red. A fine dispersion of the two will
obviously appear to be violet/purple in differing shades which I've also seen. For now, I can only assume that the blue hue is seen because of sodium
oxide and the red hue is possibly sodium superoxide. Sodium peroxide is light yellow; a pretty well known fact and one I've seen myself.
Tank |
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m1tanker78
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Addendum to my red sodium post above:
From Wiki - | Quote: | "Ozonide is an unstable, reactive polyatomic anion O3−, derived from ozone, or an organic compound similar to organic peroxide"
[...]
"Inorganic ozonides[1] are dark red ionic compounds" |
Link to the brief wiki entry: http://en.wikipedia.org/wiki/Ozonide
Seems highly unlikely given the conditions required to form as well as the low temperature decomposition and general reported instability. I don't
know what else to think. Here's a list of oxidation states and observed or reported colors pertaining to sodium:
Na2O - Sodium Oxide - silvery white (possibly bluish tint)
Na2O2 - Sodium Peroxide - light yellow (appears [off]white in certain lighting)
NaO2 - Sodium Superoxide - "yellow-orange"
NaO3 - Sodium Ozonide - "dark red"
?????
Tank
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blogfast25
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Hmm, the different coulours, assuming I'm more or less right right that thin layer diffraction (TLD) is causing the various colours is much more to do
with the oxide thickness than with the type of oxide. The red may also be caused by TLD, e.g. a bit of mineral oil forming a very thin layer.
For the kind of strange colouring effect that oxide layers can cause metals to TLD, see examples here (scroll down):
http://periodictable.com/Elements/041/index.html
Niobium metal can be given almost any colour by means of this layer anodisation.
I doubt if you're seeing superoxides, they take time to build...
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m1tanker78
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Returning to my sodium in IPA experiment...
After roughly a month, I noticed that all of the liquid was gone so I broke up and scooped out the crystals. I've been researching their composition
but came up with more questions than answers (as usual). I hit a dead end in my search and I know how much you all love puzzles. [/sarcasm] Seriously
though, I'd appreciate any leads on this.
The crystals don't melt or decompose when heated to cherry red. They turn white after strong heating. They don't seem to have any water trapped in
their structure and don't exhibit signs of being hygroscopic. I don't see how the crystals could be Na-alkoxide (low MP, 'violent' reaction with
moisture). One thing I'm sure of after a flame test is that it's a sodium compound. It definitely isn't NaOH.
Virgin crystals as removed from the vessel:
Small sample after strong heating:
Tank
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ScienceSquirrel
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That looks like sodium carbonate to me.
Sodium hydroxide and alkoxides absorb carbon dioxide from the air to form sodium carbonate, bicarbonate, sesquicarbonate, etc as various hydrates
depending on conditions.
Try adding a few drops of acid to some of the solid, I bet it fizzes.
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Neil
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Did you weigh the glass reaction vessel before and after? Perhaps silicates? Was that red heat taken inside in the shade or outside under full sun?
[Edited on 2-6-2011 by Neil]
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m1tanker78
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| Quote: Originally posted by ScienceSquirrel | That looks like sodium carbonate to me.
Sodium hydroxide and alkoxides absorb carbon dioxide from the air to form sodium carbonate, bicarbonate, sesquicarbonate, etc as various hydrates
depending on conditions.
Try adding a few drops of acid to some of the solid, I bet it fizzes. |
I put a couple of drops of conc HCl on some of the crystals and it fizzes like crazy. I initially dismissed the carbonate because it's very
hygroscopic but for whatever reason, these crystals remained [mostly] anhydrous. Thanks!
Neil, the glass wasn't attacked if that's what you meant.
Tank
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ScienceSquirrel
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Sodium carbonate is not hygroscopic at normal humidities.
The decahydrate and heptahydrate are quite stable in air and crystalline but will effloresce to form the monohydrate which will form the anhydrous
salt on heating. The monohydrate and anhydrous salt are both white powders.
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m1tanker78
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| Quote: Originally posted by blogfast25 | In all likelihood the formed sodium isopropoxide (sodium 2-methylpropoxide) is ‘salting out’ the 91 % IPA, that is: it’s driving out the water,
explaining the layers. At the same time the isopropoxide is hydrolysing to NaOH due to the water. It’s also possible that the sodium is reacting
preferentially with the water, thus forming NaOH (which then salts out the IPA). Pure IPA isn't soluble in water with high salts contents...
To answer your previous question about the suitability of 91% IPA, in short; ‘NO!’
But you can repeat the experiment in a meaningful way as follows: look up ‘salting out IPA’ (or similar terms): there are plenty web pages that
detail how to convert 91% IPA to almost 100% IPA by adding lots and lots of NaCl to it. The salt ‘pulls’ out the water leaving you, after
filtering usually, with quite pure isopropyl alcohol.
Next, instead of dunking a whole nugget into the alcohol, cut a neat piece, totally free of skin and protective oil and see how it reacts and whether
you’re getting a clean, clear solution of sodium isopropoxide in IPA. Any oil would probably emulsify into the alcohol, creating deceptive
results…
Alternatively, use any dry alcohol: methyl, ethyl, propyl…
Salting out IPA:
http://www.instructables.com/id/How-to-Salt-Out/
[Edited on 27-4-2011 by blogfast25] |
I got my hands on some pure methyl alcohol so I went ahead with blogfast's suggestion. The result was very different from the original sodium in 91%
IPA experiment. I cut 2 slivers from the same sodium nugget as before and used the 2nd sliver to eliminate as much 'face' contamination as possible. I
removed virtually all of the oil manually (no solvent rinse) then cut away the outer perimeter. In the process of doing all of this, the sodium sliver
oxidized some but without argon, there's nothing I could have done to prevent it. I'd like to think it was [at least] clean oxidation. Anyway,
2 CH3OH + 2 Na > 2 CH3ONa + H2
I believe that's the correct notation for the reaction. I observed the following differences compared to the previous:
1. A little less vigor of reaction.
2. Less white flakes sinking to the bottom.
3. No layering in the liquid during nor after rxn.
4. A few tiny white specks remained undissolved (sodium oxide?)
5. The liquid was, and remains, perfectly clear.
| Quote: Originally posted by unionised | | I'm not sure about the 3 layers but sodium hydroxide solution does not mix with IPA and wet IPA may not mix with some hydrocarbon oils.
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The lack of layering in this experiment seems to reinforce what unionised and blogfast stated about solubilities. This time around, there simply
wasn't any water in the methanol to screw up solubilities.
I'm thinking of separating the remaining methoxide solution into 3 or 4 smaller samples for further analysis to check for impurities. I don't care
much about the impurities, themselves. I believe that isolating them would be 85% of the fun. 
Here's the video clip of the reaction...
<iframe sandbox width="480" height="390" src="http://www.youtube.com/embed/idepSOh0A3c?rel=0" frameborder="0" allowfullscreen></iframe>
Tank
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blogfast25
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Nice, clean, crisp reaction Tank. Your sodium is fairly pure by the looks of it: no inclusions and such like. Of course actual purity can not be
established only this way but its very encouraging, I'd say.
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