freedompyro
holmes1880
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Does 2Al + 3S > Al2S3 Produce Gas?
I was discussing this thermite with a friend and I stated that this reaction cannot possibly be producing any gas. The only gas that could be produced
is from impurities in the mix or a incorrect ratio.
The proper balanced ratio for this reaction is 2/3 Al/S by weight, correct?
It doesn't appear to produce any gas or flame when I burn it.
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simply RED
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Such mixtures produce gas only in the initial phases of burning, when the substance undergoing reaction is hot enough to vapourise the products of
reaction. When the vapourised products cool, they chrystalize in the form of "smoke" in the air or deposit on some surface.
Conclusions: mixtures like KClO4/Al will burst a steel pipe but will not make a good rocket fuel.
When logic and proportion have fallen sloppy dead...
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bbartlog
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Sulfur is vaporized at temperatures below 500C, so it seems like some would likely turn to gas; but how much actually escaped would depend on a lot of
factors.
| Quote: | | The proper balanced ratio for this reaction is 2/3 Al/S by weight, correct? |
Based purely on stoichiometry we would expect a slightly different ratio. Since the ratio of atoms is 2:3 and the atomic weights are 27 and 32
respectively, an idealized ratio would be 54:96 which is to say 9:16. However, it's entirely possible that slight deviations from this would provide
better practical results for one reason or another. In particular, a slight excess of aluminum (which a 2:3 ratio provides) could result in less
outgassing of sulfur and/or less formation of sulfur oxides as a result of reaction with the air.
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PHILOU Zrealone
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Some S2 gas but also some H2S if moisture is present on the surface of the sulfur (via traces of H2SO4) or on the surface of the aluminium via
hydroxyde/oxyde layer.
Note that aluminium sulfide is a strong H2S generator because it is unstable when submitted to water or to air humidity, so beware of the stinky and
very poisonous gas.
Al2S3(s) + H2O(l/g) ==> Al(OH)3(s) + 3 H2S(g)
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Chemistry Alchemist
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Am i able to make Aluminum Sulfide by wrapping sulfur in aluminum foil and then setting it alight or do i need to powder the aluminum?
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bbartlog
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If you set it alight (in the open air), various oxides of sulfur and aluminum will be produced and might well predominate, though I'm sure the mess
would contain some sulfide as well. I don't know whether the aluminum really needs to be powdered, but it would help make the reaction self-sustaining
in the absence of air, which would help - i.e. you could set it alight in a steel can with a small hole in the lid (for vapors to escape), closing the
lid after starting the reaction.
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barley81
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Get a rock tumbler and steel marbles and pulverise the aluminum foil (shred it first) for a week or so until it is powdered/granulated. I tried making
Al<sub>2</sub>S<sub>3</sub> with it, with success.
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Chemistry Alchemist
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Quote: Originally posted by barley81  | | Get a rock tumbler and steel marbles and pulverise the aluminum foil (shred it first) for a week or so until it is powdered/granulated. I tried making
Al<sub>2</sub>S<sub>3</sub> with it, with success. |
Would a coffee grinder do the same as a rock tumbler? im looking to buy a coffee grinder for the sole reason for making aluminum powder
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Wizzard
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You can also empty out an old Etch-a-Sketch for some very fine aluminum particulate 
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barley81
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| Quote: |
Would a coffee grinder do the same as a rock tumbler? im looking to buy a coffee grinder for the sole reason for making aluminum powder
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I tried it once, you need to shred the foil by hand first. It just scratched up my coffee grinder and made some little bits of aluminum (not powder,
rough granules). I didn't want to let it run very long for the sake of my coffee grinder. Maybe if you let it run for a while you could sift the fine
stuff out.
On instructables there is a tutorial, "make german dark aluminum powder" or something like that. It says to add charcoal powder to the aluminum, that
makes it more reactive (no oxide layer). It takes about a week for some pretty fine powder.
If you want stearin free etch-a-sketch Al powder, you may suspend it in acetone, let it settle, decant, and dry (or something like that)
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Chemistry Alchemist
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was your coffee grider for the sole purpose for making aluminum powder or was it for coffee?
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quicksilver
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We had discussed Al powder some time back and some very workable ideas were put up.
Sourcing was via the cheapest Al foil available due to it's not having any plastic coating. I had personally tried some techniques to determine if
they were not only viable but would not harm any appliances. Most techniques were fine. However if you are considering the reduction in size of an
aluminum particulate "steps" or stages" are really mandatory. There are some issues with ball milling aside from just oxidation of the material. Lead
will contaminate and steel may spark. Additionally using a kitchen blender to reduce size initially does not appear to stain on a permanent basis if
the container is glass.
There was a great deal of discussion of the various attempts back about 2 years ago; some of the attempts did get to a very workable particulate but
the use of stearic acid appears to be a very significant step (aside from the oxidation issue) as a plateau appears at about 60 mesh.
The "Etch-a-Sketch" idea is very workable but one issue is the value of the toy as-is vs the value of the product (some people collect old toys). 
[Edited on 20-9-2011 by quicksilver]
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White Yeti
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Aluminium sulfide outgasses hydrogen sulfide gas when exposed to air. On top of that, aluminium sulfide is hard as a rock, grinding it is mission
impossible. Just dunk it in water and burn the H2S that results. Just be careful.
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Chemistry Alchemist
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yeah i wanted to make some easy H2S and use Lead Acetate to test for it, i need a blow torch to ignight the mixture tho so needs to wait :/
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