kclo4
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Hygroscopic problems with ammonium perchlorate
Is there a nice safe way to kick out the water from Ammonium perchlorate with out reaching or close to reaching 65.6°C? And how hygroscopic is it?
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We don't need a desperation plea, thank you.
[Edited on 26-12-2004 by vulture]
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JohnWW
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I doubt it. It would be best stored hermetically sealed in a vacuum, or else under dry nitrogen.
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BromicAcid
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As John WW said it should be stored without acess to moisture in the first place, keeping your hydrated sample in a vacuum dessicator with some P2O5
or AgClO4 or Mg(ClO4)2 or some other incredibly strong dessicant might dry it out in short order though.
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neutrino
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There is one method that might work for you. Add a low-boiling point liquid that forms an azeotrope with water (also with a low boiling point) and
distill the liquid and azeotrope out. Just make sure that this liquid is inert to the solid.
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kclo4
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Such as
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neutrino
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That temperature limit reduces the possibilities a good deal. If you can do the distillation under a vacuum, many options open up. At atmospheric
pressure, chloroform, diethyl ether, pentane, hexane, heptane and acetone would work, although these azeotropes are poor in water content (except
hexane and heptane) and some of these might react.
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Theoretic
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 But hexane and heptane are saturated hydrocarbons, the solubility of water in
them should be very poor! Acetone is a much better solvent for water than these.
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neutrino
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I'm not actually sure if this requires a solution or not. For example, toluene is the standard material used for this procedure.
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mick
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ammonium perchlorate is very hydroscopic, if not well sealed it will soon be a solution. As mentioned, I think it should dry out under vacuum.
The azeotropic distillation is the same as a steam distillation. The liquids do not mix so the mixture boils when the combination of partial pressures
equals atmospheric.
Limonene, bp 170 oC, is easily steam distilled from orange.
Cyclohexane works instead of benzene at 80 ish
Pentane might work at lower temperature.
Keep the stuff away from metal
mick
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kclo4
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Would propane work very well because it has vary low boiling point and is vary good solvent?
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neutrino
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| Quote: | Originally posted by mick
The azeotropic distillation is the same as a steam distillation. The liquids do not mix so the mixture boils when the combination of partial pressures
equals atmospheric.
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I was also thinking that this may be the case, but the vapor pressure of water above a dessicant is very low.
edit:
It seems that I was wrong. Vogel’s 4th mentions this effect being caused by water vapor above the hydrated salt, meaning that the small vapor
pressure is significant in the end.
This would explain why it’s hard to get completely dry solvents by redistillation from a desiccant that forms a hydrate: some of the water is
invariably distilled off.
Since AP is very hygroscopic, this would require a lot of solvent.
[Edited on 28-12-2004 by neutrino]
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mick
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Would propane work very well because it has vary low boiling point and is vary good solvent?
Can you mention what have you dissolved in propane and the conditions. I would have thought it as a crap solvent.
mick
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neutrino
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I think that if you’re planning on passing the gas through the salt at room temperature (or a slightly elevated one), all inert gasses should work
equally well.
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kclo4
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I have always hard that propane was a good solvent in liquid form but if it is not would it still work it take out the water
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mick
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I would not have thought that liquid propane is a better solvent than pentane, hexane or heptane. They will leach stuff out of rubber or plastic
causing it to go brittle and fail. Usually hexane or petroleum ether/spirits are used to precipitate stuff because of the insolubility, as in the
extraction of caffeine from tea or coffee.
If you passed a dry inert gas or dry air over the ammonium perchlorate it could take out most of the water.
If you kept the partially dried ammonium perchlorate in a sealed container with a beaker of activated molecular sieve (or another good drying agent),
the sieve should take out the rest. Replace the sieve with re-activated stuff and it should get even drier.
Be careful of recycling magnesium perchlorate as a drying agent, when contaminated it has been known to detonate.
mick
Use to dry a very hydroscopic amine HCl, 100 kg a time, in a large oven by partially sealing off the vent and blowing a bit of nitrogen from a
cylinder into the oven. Sealed it up while it was still warm and the stuff came out 98+% pure.
mick
The melting point of the amine HCl was around 68oC
mick
[Edited on 30-12-2004 by mick]
[Edited on 30-12-2004 by mick]
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kclo4
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Would sodium acetate or magnesium sulfate work better then magnesium Perchlorate or is there some reason it would also haft to be a perchlorate
compound?
[Edited on 1-1-2005 by kclo4]
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kclo4
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Should I use a nonflammable solvent like chloroform or does it matter. In other words how dangerous is it to have an extremely flammable substance
bioling in with a extremely powerful oxidizer
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SAM4CH
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I think you can use Microwave Oven for drying small amount of ammonium perchlorate, I dryed 60g and the result was very nice but be sure that your
sample does not contain any corrision material like acids which can damage the oven, please reviewMicrowave Oven Theory!!
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MadHatter
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Microwave Ovens
SAM4CH, I think you're lucky you didn't have a explosion. I would never dry out an ammonium
compound in a microwave oven.
From opening of NCIS New Orleans - It goes a BOOM ! BOOM ! BOOM ! MUHAHAHAHAHAHAHA !
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