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April 10 2012 3 10 /04 /April /2012 15:28

I have compiled a list of sources for the elements that are available to the amateur chemist. Iodine will be discussed here.  


Iodine is a lustrous, bluish-black nonmetallic element. Its vapor pressure is relatively high, a strange thing for a solid. When heated, it emits purple fumes (sublimation) which condense as crystals on cold surfaces. Iodine is the last of the four common halogens and therefore the heaviest, highest melting, and least reactive one. It is found in small quantities in nitrate ores in the Atacama Desert, where strange water-soluble minerals can survive because of the minimal rainfall. It is also concentrated in seaweed, where it was discovered. Iodine forms iodides, which are similar to all the other halides. Iodates and periodates are strong oxidizing agents, just like chlorates and perchlorates.


Note: Purchasing large quantities of iodine or its compounds may make the DEA suspect you of being a methamphetamine synthesizer.


In element form: Iodine crystals used to be sold as a water disinfectant by Polar Pure, but the DEA might have put them out of business. React tincture of iodine with slightly acidified sodium hypochlorite. Iodine crystals will precipitate (some will remain dissolved in the alcohol). Tincture of iodine itself contains about 2% iodine, 2% sodium iodide, and some alcohol.


In compound form: Iodized salt contains a trace of iodine, as do most seaweeds. Radiation exposure tablets contain potassium iodide or iodate, made to prevent the radioactive iodine from accumulating in the thyroid.


Here was my sample of iodine. My iodine always evaporates on me since I have such small amounts. This is pure iodine crystals extracted from about 0.5 mL of tincture of iodine. The vapor reversibly stains the paper and my skin brown.



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