soma
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how to make MgO from MgCO3
I want to make light burned MgO from MgCO3. I've got a thermocouple thermometer that can go up to 700C. I was thinking of just heating the carbonate
up in a pot on the stove but then thought that the temperature wouldn't get distributed well if there was a moderate amount of CO3. Also, I tried
heating up a small amount of sand in a pot and the temperature had a hard time getting past 400C.
Any thoughts on how to do it?
[Edited on 12-4-2017 by soma]
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Geocachmaster
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It would be difficult to make large quantities (because of how hot it much get), but tens of grams shouldn't be too hard. I noticed when drying out
some MgCO3 on a hotplate (about 30g) that gas started to be evolved in a similar fashion to NaHCO3 when heated, just at a higher temperature. My
hotplate maxes out at ~500C.
According to Wikipedia, decomposition of of the carbonate begins at 350C. That doesn't leave a huge margin if your hotplate only gets to 400, but it
might be enough. Try putting ten grams or so on it and heating on full, if it does start to decompose then you should notice bubbles popping on the
surface, creating little craters. Continue till no more bubbles come off, then switch to a torch or Bunsen burner for heating to get to the very high
temperature needed for full decomposition. A crucible should be able to take the temperature of 900C needed. A portable gas camping stove can reach
very high temperatures, do you have one of these? A big one probably has enough heat output to heat a larger quantity than on a hotplate, plus there
is less chance of damaging your heating source.
A metal melting furnace or kiln would be the best, maybe you could improvise something? Make a lab oven like https://youtu.be/M5oKvHktmNU?
Edit: I think the thermal decomposition of magnesium hydroxide is easier and occurs at a lower temperature. Perhaps you should convert the MgCO3 to
Mg(OH)2 and heat that. Epsom salts are very cheap and you could make a lot of Mg(OH)2 by:
2 NaOH + MgSO4 --> Na2SO4 + Mg(OH)2. Or you could do: 2 NaOH + MgCO3 --> Na2CO3 + Mg(OH)2. You could dissolve the carbonate and react that with
sodium hydroide but that would be more costly.
[Edited on 4/12/2017 by Geocachmaster]
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soma
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Thanks.
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VSEPR_VOID
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Did it work and can you post pictures Soma?
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