bquirky
Hazard to Others
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Registered: 22-10-2008
Location: Perth Western Australia
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Achiving anhydrous-ness via difusion & dilution
While once again daydreaming i came to wondering if there is any reason why one cannot 'dry out' a substance (solubility permiting) via the
following perhaps niaive process.
take the moist substance and immerse it into a great excess of a water miscible volatile solvent that the sample is not soluble in.
Vigorously mix and allow to sit
decant off fluid & water mixture
repete if necessary.
evaporate off solvent under mild heat.
The main possible floor that i can see with this schem is that the substances crystal structure would just hold onto the water too well to diffuse
into the solvent. this effect would surely be temperature Dependant however.
am i missing something obvious here ?
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Nicodem
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Registered: 28-12-2004
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But this would not be "achieving anhydrous-ness" as your tittle claims, as all it would do would be to partitionate water between the two phases
according to the partitioning coefficient of such a system. Making a substance anhydrous means to remove all the non-chemically bound water, not just
to dry it a bit. Of course, if the solvent is able to irreversibly bind water then this would make the substance anhydrous. For example, in inorganic
chemistry SOCl2 is often used this way to dehydrate some hydrates and thus make anhydrous salts.
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