budullewraagh
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bismuth oxidation
i know this probably sounds stupid, but i want to produce a nice oxide layer on a piece of bismuth, because hey, i like the colours that are produced.
what should i do to make it work in the best possible way?
i held a pellet piece with tongs over a candle flame and it just burned dark
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neutrino
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Heat it slightly below its melting point. I know that molten bismuth colors instantly on exposure to air, so this should logically work. If it
doesn’t, you probably either have low-quality bismuth (like the stuff used in ammo) or, like my pellets, the bismuth already has a thick non-colored
layer of oxide on it. This last problem can easily be fixed by melting and pouring.
If you want a nice, colored paperweight, melt your bismuth in anything it won’t dissolve (yes, it forms alloys) and pour it all at once onto an
upside down pot or pan (make sure it’s a thick one).
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S.C. Wack
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couldn't resist, again
No one asked and this has come up before, but a nifty thing to do with bismuth:
http://www.theodoregray.com/PeriodicTable/Samples/083.14/ind...
http://www.theodoregray.com/PeriodicTable/Samples/083.20/ind...
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budullewraagh
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theyre 99.9975% pure or something like that.
i found that putting one directly in a candle flame would leave a dark brown with a slight red hue stain, which could be wiped off very easily. i
actually melted a corner of my pellet. by placing the pellet ever so slightly above the flame, however, i found that the bismuth turns pink with a
little orange around the pink
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BromicAcid
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Maybe just an acid wash? When I expose some metal to acid then remove it, it will usually oxidize somewhat rapidly at least initially on exposure to
oxygen again. Although I don't think this would give a nice uniform colorful oxide.
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budullewraagh
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agreed. as well i read somewhere that a HCl or better yet a HClO4 wash would remove a bismuth oxide layer
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chemoleo
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Does anyone know how crystals as the one in S.C. Wacks link are made? Slow cooling of molten Bi (down to its MP) , or are there electrolytic ways
which produce nice big crystals like that?
[Edited on 30-1-2005 by chemoleo]
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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chloric1
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DANGER!
| Quote: | Originally posted by budullewraagh
agreed. as well i read somewhere that a HCl or better yet a HClO4 wash would remove a bismuth oxide layer |
WHOA! Do not use bismuth with Perchloric acid! As indicated in "Perchlorates--Their Properties, Manufacture and Uses" on page 48; bismuth,
when dipped in perchloric acid, forms a brown layer that explodes in a flame or simply on its own. Yeh it leaves a clean surface but I do not know
how strong the explosion is and I just wanted to keep you advised so you knew what to expect.
Curiously enough, bismuth oxide can be dissolved in 40% perchloric acid and crystallized. So,if I where to speculate, the brown layer may be a
oxide-chlorine dioxide adduct.
[Edited on 1/30/2005 by chloric1]
Fellow molecular manipulator
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neutrino
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Placing a piece of bismuth in nitric acid will remove the oxide layer and some of the bismuth, revealing a nice crystal structure. This surface
doesn’t react with air at room temperatures, though. As a side note, the surface produced by this method is quite interesting. Some patches look
black at some angle and completely reflective at another. No part of the surface absorbs any significant amount of visible light, even though most of
it looks dark at any given angle.
To grow big (~1 inch) crystals, I use the following method: make a cylindrical melt as tall as it is wide. Stop heating it as soon as all of the
bismuth melts and put some needle-tipped tweezers a millimeter into the melt, around the center. Bring the tips together, giving you a firm grip on a
pair of seed crystals. Move this around the melt a little until you can feel that the crystals have grown big enough (about 10 seconds) and remove
them. At this point, shake the tweezers with the crystals as hard as you can until no more liquid bismuth comes out of your crystals (be careful here,
280*C burns are not fun). You will end up with some nice crystals with a common nucleation point which has two small holes in it (where the tweezers
were) and a lot of nice colors. If anyone wants any pictures, I’ll post some.
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JohnWW
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Bismuth plus perchloric acid forming a brown explosive product? It could be Bi(V) pentoxide, Bi2O5.
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Axt
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Explosive Bismuth
Bi2O5 ain't explosive, in fact its made under red hot heat.
<a href="http://www.sciencemadness.org/scipics/axt/bismuth-perchloric.pdf">Nicholson, D. G. & Reedy, J. H. "<i>The Explosive Reaction
of Bismuth with Perchloric Acid</i>". Journal of the American Chemical Society, vol 57, pg. 817-8, (1935).</a>
The article doesnt give the product, but rules out ClO2, and the bismuth equivalent of "explosive antimony" (from electrolysis of SbCl3, see antimony
file in SM's library).
[Edited on 9-12-2005 by Axt]
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