teodor
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Melting NaOH in a glass tube
I tried to analyze some unknown substance with a melting point close to that of NaOH. So, I did a reference test to compare how NaOH melts. I've got a
Pasteur pipette, sealed one end and put a tiny amount of OTC grade NaOH inside. On melting it becomes instantly boiling (that was I thought when I saw
it). I did the check that my NaOH is not a hydrate (by titration with HCl), it isn't. So, I think this "boiling" is a violent reaction of molten NaOH
with glass. Not surprised, but what exactly this reaction is and what is the gas which bubbles?
[Edited on 18-7-2019 by teodor]
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fusso
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2NaOH+SiO2=Na2SiO3+H2O
Na2SiO3+2NaOH=Na4SiO4+H2O(?)
Na2SiO3+xSiO2=Na2O*(x+1)SiO2
So the gas maybe water vapour?
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teodor
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Oh, thank you, fusso. So, I believe it is the same reaction as between NaOH water solution and glass. And SiO2 acts like an acid.
Actually I was surprised by the reaction dynamic. I didn't expect that this reaction is so violent when NaOH is molten. Now I can use this simple test
as a check for hydroxide.
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morganbw
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Quote: Originally posted by teodor  | Oh, thank you, fusso. So, I believe it is the same reaction as between NaOH water solution and glass. And SiO2 acts like an acid.
Actually I was surprised by the reaction dynamic. I didn't expect that this reaction is so violent when NaOH is molten. Now I can use this simple test
as a check for hydroxide. |
I would google on how to test for hydroxides. I do not think this is a test you want to add to your bag of tricks.
Lots of info on this.
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teodor
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Well, this test, also, probably, will distinguish between NaOH and Na2O2, Na2O.
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