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Fleaker
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As far as lighting a redox composition, (standard iron oxide/aluminum thermite) a sparkler or magnesium ribbon will work if it is finely ground.
An even more interesting reaction with bromine is to try it with magnesium powder rather than aluminum powder. A big difference in terms of the
speed. It takes about 15 to 30 seconds for bromine to get going on aluminum foil (time for it to heat up) but with magnesium, it's almost
instantaneous. Obviously, make sure to do any reaction with bromine (or any of the halogens) outdoors.
Question: Has anyone noticed that after you do a large Br and Al reaction and go to clean out the flask, massive volumes of HBr is ejected in to the
air? Happened to me some months ago, and I was glad I got in under the hood quick.
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praseodym
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Do you mean using a Mg fuse to start off the reaction? Is it something like the thermit reaction?
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neutrino
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I think he was just talking about mixing magnesium and bromine instead of aluminum and bromine.
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ChemicalBlackArts
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As far as storing bromine(l) goes, vermiculite is excellent in extending reagent grade bromine's shelf life. FLINN Scientific ships any liquid
bromine orders with about a pound of vermiculite.
And regarding chlorine, it really isn't that dangerous to handle, given a fume hood, and proper synthesis. I normally produce aqueous chlorine
using equal volumes of normal bleach (NaOCl) and 12M HCl, and displace the other halogens from there.
--Chemistry in my veins--
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ayumichen
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who can explain the mechanism that Al reacts with I2 by water as the catalyst?
Why use water?What's the mechanism?
[Edited on 21-8-2006 by ayumichen]
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hodges
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| Quote: | Originally posted by ayumichen
who can explain the mechanism that Al reacts with I2 by water as the catalyst?
Why use water?What's the mechanism?
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Someone who knows more about this than I do can confirm and/or invalidate this, but I'm guessing that the iodine forms some hypoiodous acid with
water. This acid dissolves the oxide coating that is always present on the surface of aluminum, allowing the iodine to come in contact with the
aluminum metal that was previously protected by the oxide.
Hodges
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12AX7
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Should be something like I2 + H2O > HI + HOI, where the HI dissolves Al2O3 more or less as rapidly as HCl does.
Tim
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ayumichen
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Thank u!
In fact , I'm from China.We are discussing this problem in our bbs,too.
I found this bbs on Yahoo,accidentally.
PS:where r u from?
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lys_134
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In my opinion,HI produced by I2 resolving is very little.Though the reaction one(AlI3+H2O->Al(OH)3+HI)is great,acid is not needed at first.If the
oxide membrance is very thick,then the acid won't destroy it easily besaides I- likes Cl-.So I think H2O is exactly as a diffuse phase at first,then
the reaction two(Al+I2->AlI3) change into liquid-solid pattern.As H2O->I2 arising,the bond of I-I is impaired,the reaction will become easier.At
this time,AlI3 is protected by the oxide membrance,the reaction one is in incentive period.With time going on,H+ become more and more,the oxide
membrance is destroyed.Then lots of AlI3 react with H2O,arising great heat.So I2 and H2O change into gas.The reaction two change into gas-solid with
the heat of H2O pattern.
[Edited on 22-8-2006 by lys_134]
nothing to say but miss
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