oxybate
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Extraction of Iodine from Tincture - A Question of Mechanics
I thought it would be interesting to make an experiment out of extracting
elemental Iodine from Iodine tincture using the method involving HCl and H2O2. The strongest tincture I could find was one called Churchill's
Iodine, which is apparently named after an old formula for creating a 16.5% iodine tincture using Iodine, Potassium Iodide (to increase the
dissolution of the Iodine), Water and Isopropyl Alcohol. A little detective work resulted in finding an entry in the 1911 National Druggist revealing the improved, and presumably modern-day version of Churchill's formula to be "16.5 grams Iodine, 3.8 grams
Potassium Iodide, 25mls Water, and enough alcohol to make a 100ml" solution. I have a couple questions I hope you all could answer: There is no mention of what the 16.5% means on the 1 Pint bottle I have. Should it be assumed to be w/v and, therefore, that there are
approximately:
78 grams of dissolved elemental I2 in this bottle (16.5g x 473ml /100ml), and 18 grams of KI in this bottle (3.8g x 473ml
/100ml)?
In the process of oxidizing the KI to liberate the Iodine, can I expect an additional 13.8 of Iodine, for a grand total of 91.8 grams of
I2 recovered from this experiment? (Iodine makes up 126.9/166 or 76.44% of the molecular weight of KI and therefore .7644 x 18 grams of
available KI = 13.8g of I2)
What is the mechanism behind the addition of the HCl and the H2O2 to drop out the Iodine? I imagine the point of the reagents is solely
liberate the Iodine from the KI). Is it also somehow getting the dissolved I2 out of solution as well?
What would be the stoichiometric amounts of the HCl and H2O2 needed to optimally extract all the Iodine from this Churchill's Iodine
Tincture? Thanks SO MUCH in advance for your help.
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mnick12
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Well the HCl would react with KI to give HI and KCl, and the HI would be oxidized to elemental iodine. Well you would need equimolar amounts of H2O2
and HCl to turn you KI into I and KCl, but thats going to take some extra brain power since both are solutions. I dont really feel like figuring out
those numbers, but it really easy and I think you should be doing it.
Hope that helped a little, and good luck!
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oxybate
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That extra brain power is what I need, as I am still learning, albeit slowly. I'd rather have the appropriate amounts of the HCl and H2O2 so that I
don't end up wasting the precious tincture.
Thanks for your input. Can anyone else help?
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Contrabasso
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In the places where Iodine is restricted the tinctures are also restricted except in the smallest concentration and bottle size, so the pint of strong
tincture that you have may not be repeatable. Hospitals now have to account for all the tincture of iodine that they use, like a controlled drug.
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