It used to be easy to obtain iodine crystals for water purification purposes. Backpackers often used just a few crystals to treat an entire quart of water to make it safe for drinking. However, in 2007, the U.S. Drug Enforcement Agency changed iodine from a list II to a list I substance because it is an integral part of the process of making homemade methamphetamine. This upgrade made it more difficult for the average person to obtain pure iodine. Yet iodine can be made easily from potassium iodide, a common chemical found in a typical laboratory, as well as in health food or supplement stores. The entire process takes only a few minutes but requires several other chemicals also commonly found in a chemistry lab, yet also easily purchased at various retailers.
Things You'll Need
- Potassium iodide
- Hydrochloric acid
- Hydrogen peroxide
- Coffee filter
Making Crystal Iodine
Put a small amount of potassium iodide (approximately 100 mg) into a beaker. It is not necessary to measure out an exact amount.
Add enough water to dissolve the potassium iodide. About 100 ml, or slightly less than half a cup, should be enough. Shake the beaker until all potassium iodide is dissolved.
Add enough hydrochloric acid to double the volume of the solution. Use extreme care when handling the acid, as higher concentrations are extremely corrosive.
Add about five times the solution's volume of hydrogen peroxide. This should cause the solution to turn a dark brown. This is actually the iodine crystals, the desired final product, precipitating out.
Pour the entire solution through a coffee filter. Wash the crystals with water to remove any remaining hydrochloric acid. It may take several washes to remove all acid completely.
Finally, let the iodine crystals air dry.
Tips & Warnings
- Muriatic acid is another name for hydrochloric acid and can be purchased at a hardware store. Commonly found in health food or supplement stores, potassium iodide is used in the event of potential exposure to nuclear material. The supplement is used to protect the thyroid from absorbing radioactive iodine that may have been released.
- Use care when handling all of these chemicals, particularly hydrochloric acid, which is extremely corrosive in high concentrations. Many stores sell special rubber gloves that are resistant to the corrosive effects of acid. The reaction may release a small amount of noxious chlorine gas. Therefore, the entire process should be performed in a well-ventilated area.
- Photo Credit Diana Dolzhikova/Hemera/Getty Images
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