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Author: Subject: cheap NaOH
halogen
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[*] posted on 14-11-2004 at 04:43
cheap NaOH


2NaHCO3+heat --> H2O+CO2+Na2CO3
Na2CO3+heat --> Na2O + CO2
Na2O + H2O -->2NaOH
But heres the problem (well not really)
Would Na2O react with oxygen in air to form Na2O2?




F. de Lalande and M. Prud'homme showed that a mixture of boric oxide and sodium chloride is decomposed in a stream of dry air or oxygen at a red heat with the evolution of chlorine.
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Esplosivo
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[*] posted on 14-11-2004 at 05:38


halogen, that's not the problem. You see group I carbonates are highly stable, and do not decompose by heat to give the oxide except lithium carbonate. Therefore the following reaction cannot occur:
Na2CO3+heat --> Na2O + CO2

The Na2O + H2O --> 2NaOH would occur if you succeded in making Na2O anyway. Na2O2 would simply react with water giving the hydroxide and O2 gas.




Theory guides, experiment decides.
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rikkitikkitavi
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[*] posted on 14-11-2004 at 06:49


Actually it does occur. T
he problem is that the decomposition rate is slow , even at the melting point of Na2CO3 so the temperature has to be increased even further , and a melt of Na2O is extremely corrosive towards most materials. (we are talkning 1100-1200 C)

Na2O2 is not stable at this temperatures, so it would not be formed.

Also, NaHCO3 is not very cheap compared to NaOH- but if you have quicklime (CaO) or lime hydrate( Ca(OH)2 ) mixining this solid with NaHCO3 or Na2CO3 solutions preciptate CaCO3 and leaves a NaOH solution (old industrial route )

/rickard
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kazaa81
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[*] posted on 14-11-2004 at 09:54
Point of view...


Hallo to all,

this probably won't help, but I decided to post.

NaOH seems to me to be cheap itself....if you buy it in hardware store or something similar in your country.
If you buy it at a scientific supplier, depends too on what supplier, it would be less cheap.
NaOH from hardware store that I've buyed is 97-98% pure, this suffice to me but, if you need it very pure for particular analytical experiments, then a scientific supplier is your only alternative, probably.

Have fun
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