Panache
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Sodium Oxide
Wiki claims heating sodium carbonate over 1000C produces sodium oxide, analogous to the heating of Calcium carbonate to form calcium oxide. I find
this difficult to believe given potassium carbonate certainly does not revert/decompose to the oxide when strongly heated. Is wiki FOS here?
If not, anyone got anything interesting to do with some, sounds like a fun chemical, would be super hygroscopic i imagine and probably a great co2
absorber.
What the hell, for shits and giggles i'll throw some bicarb in the kiln now.
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garage chemist
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Hollemann-Wiberg says Na2CO3 will not decompose at all, not even at the highest heat, just eventually evaporate. So I say that wikipedia is in the
wrong. But of course you can argument with thermodynamic equilibrium and that decomposition will happen if the CO2 partial pressure if low enough, but
it doesn't seem like it is practically possible here.
Sodium oxide can be prepared by burning sodium to sodium peroxide, and heating this with more sodium to reduce it to sodium oxide. This is described
in Brauer.
Very strong heating of sodium nitrate will also definately cause it to eventually give sodium oxide. The problem is finding a suitable vessel to do
this in.
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Taoiseach
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Sodium nitrite, NaNO2, is also said to decompose @320°C giving off NOx fumes. Theoretically this should leave only sodium oxide.
Sodium nitrate, NaNO3 however is quite difficult to decompose thermally. Only little NaNO2 is formed upon heating. So its probably more feasible to
start with NaNO2. The key to success here is to exclude moisture and CO2, otherwise only NaOH and Na2CO3 is obtained. A quartz tube with a steady
stream of some inert gas might work, but in my experience quartz tubes tend to crack in these kind of experiments. The melted solid adheres very
tightly to the glass. Upon cooling it shrinks/expands and breaks the glass. I killed 2 or 3 pieces of expensive lab glass until I switched to empty
food cans for these kind of experiments 
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Globey
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The elegance of Panache's idea would be that this would be a completely OTC source of food grade NaOH (via heating strongly the bicarbonate), and then
adding water.
I bet if someone built mini professional versions of liquid air, Downs Na cell, ammonia plant (all made of same/similar materials of their larger
brothers'), people would pay a few grand each.
Imagine adding table salt, plugging in, flipping a switch, and coming back to sodium metal (& optionally, Cl2). Imagine hitting the switch, and
getting a hundred ml of so of liquid air.
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kclo4
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Desiccating, absorbing gases, or further oxidizing it to a peroxide/superoxide would be about the only interests I would think.
| Quote: | | he elegance of Panache's idea would be that this would be a completely OTC source of food grade NaOH (via heating strongly the bicarbonate), and then
adding water. |
or you could just buy the NaOH an isle over from the baking soda. If you cant get that then CaO and Na2CO3 would work as well to make NaOH. Making
NaOH from NaO is just horrible IMO.
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Globey
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"A" completely OTC source, not the only. "Food grade", not Red Devil grade. Besides, didn't they stop selling Red Devil? Why horrible, just add
water and you got pure NaOH solution, good 'nuff for making great Philly/NY NY pretzels. Sorry, I would see this as more elegant than the CaO method
(if it actually worked, which it doesn't, apparently). The feedstock would be an already food grade ingredient. Garbage in, garbage out.
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Sedit
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Globey being able to reach 1000 degrees C is not exactly over the counter. Not to mention where even though I lack personal experiance many people
have reported successful production using CaOH method.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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chief
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Na2CO3 begins to decompose at 800 [Celsius] ; the stuff foams then, gets out of the crucible and into the furnace, and easily ruins it if the ceramics
is acidic ... .
Besides probably K2CO3 decomposes too ... ; the fact, that its found in the ash of very hot burning wood doesn't mean any temp-resistance, since the
K2O may well have reacted with CO2 when already cooled to a temperature where K2CO3 is stable.
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Globey
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Sedit, generally it is acknowledged that OTC in these contexts referrers most likely to reagents (which may have controls), unless you are in Texas,
and that would involve glassware as well sometimes (but not to the exclusion of chemicals.) But, for sake of argument, even if OTC is being used in a
broader sense, a kiln can still be bought cash & carry, so it is OTC.
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Sedit
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Sure I guess.......
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Globey
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Heh, I'm not the one who picked it apart.
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Sedit
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F'it
Never mind
[Edited on 11-4-2009 by Sedit]
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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Panache
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Quote: Originally posted by chief  | Na2CO3 begins to decompose at 800 [Celsius] ; the stuff foams then, gets out of the crucible and into the furnace, and easily ruins it if the ceramics
is acidic ... .
Besides probably K2CO3 decomposes too ... ; the fact, that its found in the ash of very hot burning wood doesn't mean any temp-resistance, since the
K2O may well have reacted with CO2 when already cooled to a temperature where K2CO3 is stable. |
Thanks you could have told me that before i did this for shits and giggles.
I'm very fortunate to only have chewed out one fire brick i used as a platform so the crucibles were eye level with the lower viewing plug otherwise
the bottom of the kiln would have been chewed out.
I have had this kiln for a couple of years but never use it, largely because i am so ignorant. I really must learn further before doing more work in
it.
The crucibles all cracked to random pieces, they were those german porcelain evaporating dishes, why would this be, was my ramp rate at 50C/min set
way too high? The steel crucible i had in there to see if it would survive was turned to some crazy reduced shell of itself. The slaked lime just
turned darker, not into CaO, and one of the pieces of broken porcelain had managed to sit sidways and as such didn't spill all of its liquid. it had
an clear green glass-like substance in it. I had the kiln set to go to 1040 and hold there for 15mins.
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Sedit
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If you need any small pointers Panache just PM me. Ill show you how to make cleaning of the kiln a breeze and some other small tidbits. Iv had mine
for some time and took classes for stuff like this.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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not_important
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The alkali carbonates and oxides are pretty agressive towards stuff with much SiO2, Al2O3, TiO2, or even ZrO2/ZrSiO4 in them. SiO2 goes the the
alkali silicate and so on, in effect converting the ceramic to a lower melting glass that generally has much different thermal expansion than the
original ceramic.
Li is worse that Na and K, in particular Li2O seems to attack many ferrous allows that Na2O does little to.
That temperature profile was too fast and short to do a decent job decomposing CaCO3 without additional airflow.
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JohnWW
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Another problem would arise if the oxide product of such pyrolysis of an alkali metal salt is allowed to cool in the presence of air., even if it
could be done in a suitably alkali-resistant vessel. The presence of moist air would quickly result in the formation of the hydroxides, and probably
also peroxides and hydroperoxides and (in the case of K, Rb, Cs) superoxides, all of which are also very deliquescent, along with small amounts of the
bicarbonates and carbonates if CO2 is present.
[Edited on 12-4-09 by JohnWW]
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chief
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_Stainless_ steel lasts for a while, even at 800 Celsius and with Na2CO3 melt in it. But better have this in another stainless steel vessel, because
at the end it will get some holes too ...
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