DalisAndy
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Sodium sulfate hydration
Can Sodium Sulfate have other hydrate states other than 10?
Elements Collected: 19/81 (Excluding all radioactive, using placecard for those)
Any tips or good sources are welcome.
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Metacelsus
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The heptahydrate and the anhydrous salt are the other two common ones.
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annaandherdad
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The solubility curve of Na2SO4 has a sharp cusp at the temperature at the transition between two hydrates.
Any other SF Bay chemists?
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Praxichys
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Unless specified otherwise, sodium sulfate is usually a mix of air-stable hydrates.
I found a really interesting paper:
"We experimentally show that under real world conditions, both thenardite (Na2SO4) and mirabilite (Na2SO410H2O) precipitate directly from a saturated
sodium sulfate solution at room temperature (20°C)."
http://hera.ugr.es/doi/14997496.pdf
Analysis would be the best way to know for sure. Finding water content is easy - just weigh a sample, heat, and then weigh again.
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Upsilon
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Thought it appropriate to note that this does not work for all hydrated materials. Chemicals like H2SO4 and P2O5 are almost impossible to dehydrate,
and water content would need to be determined by more specialized methods such as titration.
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DistractionGrating
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I have a bag of sodium sulfate from this source http://www.dharmatrading.com/chemicals/glaubers-salt.html that claims to be anhydrous, but now I'm dubious. I guess I'll have to do something
like creating a solution with a known weight of the sodium sulfate salt, and then adding a slight excess of SrCl2 (I'd use BaCl2, but I don't have
any), and then titrate the remaining Sr with EDTA to determine how much Sr precipitated as SrSO4.
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Upsilon
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Quote: Originally posted by DistractionGrating  | | I have a bag of sodium sulfate from this source http://www.dharmatrading.com/chemicals/glaubers-salt.html that claims to be anhydrous, but now I'm dubious. I guess I'll have to do something
like creating a solution with a known weight of the sodium sulfate salt, and then adding a slight excess of SrCl2 (I'd use BaCl2, but I don't have
any), and then titrate the remaining Sr with EDTA to determine how much Sr precipitated as SrSO4. |
Why go through all of that trouble? As mentioned above sodium sulfate can be largely dehydrated by simple heating.
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DistractionGrating
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| Quote: Originally posted by Upsilon |
Why go through all of that trouble? As mentioned above sodium sulfate can be largely dehydrated by simple heating. |
Because I was paying attention to this:
Plus, I have everything I need to do the analysis I describe readily at hand. That, and the use of the word "largely" make me nervous, especially if
I need to have an accurately known concentration of the substance in a stock solution. If nothing else, I could confirm successful conversion of the
decahydrate to the anhydrous with this method.
However, I must concede that with a little googling, I found that sodium sulfate is actually used as a primary standard for S, at least by this
author: https://books.google.com/books?id=ELQud4ftNX0C&pg=PA446&...
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DalisAndy
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So I'm going to assume that H3BO3•Na2SO4 will completely dislocate in water? Making trimethyl borate and need a drying agent and saw that Na2SO4 is
one.
Elements Collected: 19/81 (Excluding all radioactive, using placecard for those)
Any tips or good sources are welcome.
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Amos
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You're still wasting your time if you don't have sulfuric acid. It's necessary for a decent yield. In addition, most drying agents are not added to a
reflux but rather a water-containing mixture is just dried over it at room temperature.
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DalisAndy
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Trimethyl doesn't require sulfuric acid. Or an acid catalyst. I'm just impatient so it should work?
Elements Collected: 19/81 (Excluding all radioactive, using placecard for those)
Any tips or good sources are welcome.
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Amos
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Are you trying to make methanol burn green? Or are you trying to produce a significant quantity of trimethyl borate?
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DalisAndy
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I'm not trying to make a significant amount, I just wanted a simple experiment that I could test my new lab equipment on
Elements Collected: 19/81 (Excluding all radioactive, using placecard for those)
Any tips or good sources are welcome.
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DistractionGrating
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| Quote: Originally posted by Upsilon | | Why go through all of that trouble? As mentioned above sodium sulfate can be largely dehydrated by simple heating. |
FWIW, I weighed some of my Na2SO4, heated it at 200C for a few hours, cooled, and then weighed again. Both before and after weights were exactly the
same.
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