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Mixing the Reactants
Make an iodide salt solution. Put 30 grams (1.1 oz) of solid iodide salt (e.g. sodium iodide or potassium iodide) into a glass container. Add enough water to dissolve the salt and stir with a glass stirring rod. Continue adding water and stirring the solution until all of the salt has been dissolved. Heating to approximately 120 ºF (~50 ºC) will help the dissolution process tremendously.
Cool the iodide solution. Place the glass container in an ice bath. Allow the solution to sit in the ice bath for 5 to 10 minutes and cool. The solution needs to be cool and in an ice bath before adding the sulfuric acid, as this addition will generate a lot of heat.
Add sulfuric acid. Allow the solution to remain in the ice bath. Add sulfuric acid by pouring 2 milliliters (0.068 fl oz) into the solution at a time. At first, the solution will become pasty. Keep adding sulfuric acid until the solution has become a black liquid. Sulfuric acid is extremely dangerous and corrosive. Always wear eye protection and gloves when working with it. You will begin to see color changes as soon as the sulfuric acid comes in contact with the solution and iodine begins forming. The fumes produced by this step are highly toxic. It should be done in a fume hood.
Washing the Iodine
Pour the solution into the ice bath. Once you've finished the reaction, you will need to pour the solution into ice water. The original ice bath works well for this purpose. Allow the new solution to sit for 5 to 10 minutes, or until the iodine has settled at the bottom.
Decant the remaining liquid. When the iodine has settled at the bottom, you can pour off the excess liquid. Be careful not to dump the solid iodine out as well. Once the brown liquid has been poured off (or decanted), you will be left with wet iodine.
Wash the iodine. The wet iodine slurry will still contain excess sulfuric acid. To rinse away this acid, pour more water onto the slurry and stir. Allow the slurry to settle, and again pour away the excess liquid. Repeat this at least 3 times.
Filter the iodine. You need to remove the water from the iodine slurry to yield a more pure form of iodine powder. Pour the slurry through a paper filter into a new beaker. The filter will allow the water to pass through, and it will hold back the solid iodine. The solid on the filter paper is the iodine. The liquid can now be discarded. Using vacuum filtration will dry the iodine even more effectively.
Distilling the Iodine
Fill a round bottom flask with ice. Make sure that the flask you choose is big enough to rest on top of an available beaker without falling inside. The flask of ice will allow the iodine gas to cool rapidly to a solid.
Heat the iodine in a beaker. Place the iodine in a beaker. Put the round bottom flask full of ice on top of the beaker. Heat the beaker on a hot plate to turn the iodine to a gas. The whole process is extremely messy and the large amount of iodine vapor will stain everything. Do not do this indoors. Iodine gas is toxic, so this should be performed outside or inside a fume hood. The iodine will form a purple gas and solidify into a purple solid.
Scrape the iodine off of the round bottom flask. When the iodine vapors come in contact with the cold round bottom flask, they will cool rapidly. This will cause the iodine to solidify and stick to the flask itself. Once this happens, you can simply scrape your iodine off of the flask to collect it. Heating and purifying the iodine is not necessary. It is an optional step to obtain a more pure version of the chemical.
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