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How to Make Iodine | ChemistryTwig

How to Make Iodine

You used to be able to buy iodine crystals… but that’s no longer the case. Unfortunately iodine crystals are used in the production of meth, and just like anything else used in the production of meth, it has become regulated. The good news is, there are ways to make iodine! Here’s one method of how to make it, and a simpler one that almost anyone can do is included at the bottom.

Warning: Do not ingest this iodine. Not only would it taste horrible, and leave your mouth looking as though a dye bomb went off inside, but around 2 grams is enough to cause death. This is not the same iodine you find in vitamin supplements, this is elemental iodine! Prolonged, sometimes even brief, contact with skin can cause lesions and nasty discoloring. Wear gloves when handling iodine, and do this experiment in a well-ventilated area. Also, all the normal precautions apply- wear goggles, don’t light anything on fire that shouldn’t be on fire (i.e. everything but the lamp/burner), and never work with chemicals that you aren’t comfortable with or don’t know the dangers of. This lab procedure is meant for educational purposes only.

Okay, so you’ll need to potassium permanganate, potassium iodide, sodium bisulfate, water, rubbing alcohol, two test tubes, a stopper with a hole in the top, a bent glass tube, and a flame source.

Everything but the alcohol and flame can be found here.


Iodine production supplies

I have to admit, I went without a scale for this experiment and eyeballed about how much of each chemical to use. This is normally very bad practice and I wouldn’t recommend it. However, it works well for this experiment since the exact amount created is not of concern. The ratio of volumes of each chemical are 1 part KI to 1 part KMnO4 to 3 parts NaHSO4. I used a pinch of KI, a pinch of KMnO4 and about 3 pinches of NaHSO4. I then added about 3 drops of water to the mixture.

Here's what the mixture looked like.

Here's what the mixture looked like.

Cool, now your mixture is all set. Cap it and place the bent glass tube in the top. Take another test tube and add about 8ml of rubbing alcohol. Iodine dissolves readily in alcohol. Get your flame ready and either a pair of test tube holders or a test tube clamp.

Place the open end of the bent glass tube into the test tube with rubbing alcohol. Place the end of the glass tube just above the alcohol.

The set up.

The set up.

Within a few seconds of heating the mixture (now turning to solution) you should see some purple gas forming. Very quickly some residue will be coming out of the glass tube. Every once in awhile dip the end of the glass tube in the alcohol to dissolve some of the residue.

NOTE: The solution may start to boil rapidly. If/when this happens remove the heat source until it settles down.

I see Iodine gas!

I see Iodine gas!

Pretty soon the gas will stop being produced. Unfortunately, this means the end of Iodine production :(. No worries though, there’s more cool stuff to come!

When I did this experiment I put a little too much rubbing alcohol in the collection test tube, making a weak solution. Your solution will probably be a little bit darker, but this is what I ended up with:

Not as purple as I'd like.

Not as purple as I'd like.

One you have your solution, the final step is easy! Add water to your solution until you see a precipitate forming. Elemental iodine is not all that soluble in water (about 1 gram/3.45L), so it will precipitate out when water is added. Since only a little bit of iodine was created, don’t add too much water or it might almost all dissolve.

NOTE: Adding some potassium iodide to the solution with the precipitate will bring the solid iodine back into solution.

Finally, extract the precipitate and let it dry.

The Easier Way

So, that was the complicated (but cool) way of making iodine crystals. The other way is much easier and involves a trip to your local drug store. Pick up a bottle of iodine solution (usually labeled iodine tincture) and a bottle of hydrogen peroxide (even if you have a stuffy nose, resist the urge to buy Sudafed along with these). The highest grade of each will produce the best results.

Mix the two together and let the mixture sit for awhile. Iodine will precipitate out.

Yes, I know, this was is much easier and probably more environmentally friendly. However, it’s wicked fun to see iodine gas and using a flame makes everyone happy.


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