Picric-A
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sodium perchlorate from chlorate
In a book i read it mentions sodium perchlorate can be made from sodium chlorate by heating it:
4NaClO3 + Heat --> NaCl + 3NaClO4
has anyone ever tried this? if so what temperature must you heat it to and for how long?
i ave a endless supply of weedkiller grade sodium chlorate so this would prove very usefull for me. 
Picrc-A
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garage chemist
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Yes, I've done this.
You have to heat it in a clean porcelain crucible to a temperature where there is slight but constant fizzing from oxygen evolution (I don't remember
the exact temperature- It was around 400°C I think, but you don't really need a thermometer).
The perchlorate forming reaction is not happening unless there is some oxygen loss as well.
Keep the clear liquid slightly fizzing (several hours!) until it starts to turn into a mush (NaCl starting to precipitate) and further until it is not
liquid anymore, despite the heating.
Then let cool down, dissolve in small amount of hot water and add conc. HCl under the fume hood while heating until no more ClO2 is being given off
(destruction of chlorate).
Then add some sodium metabisulfite to reduce the last remains of chlorate.
Then precipitate KClO4 by adding KCl solution while hot, then cooling and filtering.
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Picric-A
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cool, thanks for the information.
will the conc HCl not destroy any perchlorate?
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garage chemist
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No, it won't. ClO4- in aqueous solution is quite unreactive.
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hector2000
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| Quote: | Originally posted by garage chemist
Yes, I've done this.
You have to heat it in a clean porcelain crucible to a temperature where there is slight but constant fizzing from oxygen evolution (I don't remember
the exact temperature- It was around 400°C I think, but you don't really need a thermometer).
The perchlorate forming reaction is not happening unless there is some oxygen loss as well.
Keep the clear liquid slightly fizzing (several hours!) until it starts to turn into a mush (NaCl starting to precipitate) and further until it is not
liquid anymore, despite the heating.
Then let cool down, dissolve in small amount of hot water and add conc. HCl under the fume hood while heating until no more ClO2 is being given off
(destruction of chlorate).
Then add some sodium metabisulfite to reduce the last remains of chlorate.
Then precipitate KClO4 by adding KCl solution while hot, then cooling and filtering. |
Please explain more
how much metabisulfite?
NACLO4 wont Decompose at 400c?
[Edited on 20-6-2008 by hector2000]
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woelen
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NACLO4 does not exist, the proper formula is NaClO4.
I think that Garage chemist is rather clear. Keep jeating the NaClO3 for a few hours and keep it slightly fizzling. The temperature is not important,
just look at the liquid and as long as it remains liquid and fizzling, you have to continue heating. But don't heat it too much. The fizzling must be
weak, not strong, such that it starts foaming.
At a certain point, the fizzling stops and the liquid solidifies, despite the heating. If that point is reached you stop and let the stuff cool down.
Next, the solid stuff is dissolved as described above. The treatment with HCl destroys most chlorate, while not affecting the perchlorate. Even
concentrated hydrochloric acid does not attack perchlorate in cold aqueous solution. After this treatment, add some sodium bisulfite. The amount is
not critical. Add little pinches of the solid and dissolve each pinch. Keep adding pinches of this material, until you notice the smell of sulphur
dioxide (if you don't know that smell, then make some by adding some bisulfite to dilute hydrochloric acid and then carefully smell that).
With this info you should be able to work it out.
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hector2000
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May we use just sodium bisulfite for destroy chlorate?
Temp should be 400?
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