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Author: Subject: how much water in ether
soma
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[*] posted on 11-11-2012 at 07:13
how much water in ether


Are there any simple methods to determine if ethyl ether is anhydrous - or how much water is in it? Like a test strip?

Thanks.
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Vargouille
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[*] posted on 11-11-2012 at 07:38


Of course. Adding a small amount to potassium or sodium will result in a reaction if there is water, but no reaction if there is not. Anyhdrous copper sulfate also works, as it will absorb water and become blue. If there's no water, it'll stay white. You can make the anhydrous copper sulfate by heating the pentahydrate until it is no longer blue. Alkali metals can either be made or purchased.
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kristofvagyok
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[*] posted on 11-11-2012 at 08:05


Diethyl ether can contain a LOT water, even up to 10%.

Adding alkali metals is NOT recommended, because potassium will ignite it, and sodium can ignite it. Also the low boiling point of ether and the highly exothermic reaction between alkalies and water is not a good idea.

Add anhydrous potassium carbonate, magnesium sulfate, sodium sulfate or the previously mentioned copper sulfate to dry it, or determine the water cont. of your ether.




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[*] posted on 11-11-2012 at 09:35


Thanks. I'll try the copper sulfate. I had been 1st drying it with molecular sieve and then adding P205 and distilling. I tested it with LAH after the sieve and then again after the P205. It fizzed alot less after the P205.
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[*] posted on 12-11-2012 at 06:33


Would you know how sensitive the anhydrous copper sulfate is?
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[*] posted on 12-11-2012 at 15:50


You could weigh the K2CO3 making sure you weigh any additional you add. Then because the ether is easy to remove you can re-weigh the (hydrated) K2CO3 and calculate the amount of water.



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