# Can someone help me figure out some chemistry stuff?

#1

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.

#2

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.

#3

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?

#4

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