Can someone help me figure out some chemistry stuff?


So, I have this stuff called Lugol’s Iodine solution, 2% - and I don’t know how to figure out the exact measurements of the chemicals. The website says this…

Calculating Number of MG’s of Iodine and Potassium Iodide per Drop of Lugol’s Solution:
LUGOL’S 5%: Each VERTICAL drop is about 6.25 mg’s of iodine/potassium iodide (2.5 mg iodine, 3.75 mg potassium iodide) and 2 drops is about 12.50 mg’s of iodine/potassium iodide (5.0 mg iodine, 7.50 mg potassium iodide). Compared to other’s, J.CROW’S® Lugol’s Solution offers big savings.
LUGOL’S 2%: Slightly less than 1/2 half the above measurements.

It’s maddeningly unscientific, I know. “about” and “slightly less” - it’s not an ideal product, but it’s one that I already have. I have most of a bottle left and since my recipe has gotten pretty expensive, I would like to use this until it’s gone before I buy something better. Can anyone help me figure out approximately how much iodine/potassium would be contained in one drop of the 2% solution?

Any help would be appreciated.


Assuming that drops of the 5% and 2% solutions are of equal volume, the content of the 2% solution is 2/5 times the content of the 5% solution.

That is: (2.5 mg iodine, 3.75 mg potassium iodide) * 2/5 = (1 mg iodine, 1.5 mg potassium iodide)
1.5 mg of potassium iodide has 0.353 mg of potassium and 1.15 mg of iodine.

So, 2.15 mg of iodine per drop.


Thanks. What I was wondering though, and just realized that I completely neglected to add to my post, was this…is potassium iodide part potassium? Does that need to be calculated as well?


Of course it is, but the amount is completely negligible.

The relevant part is the iodine: 2.15 mg of iodine is 14 times the RDI
Potassium, on the other hand: 0.353 mg of potassium is 0.01% of the RDI