After reading many posts regarding the extraction of Iodine crystals from tincture, this is what swim has come up with.
Most tincture's contain Potassium Iodide (KI) and Iodine salt (I). KI has to be reacted with HCl acid and an oxidiser (Hydrogen Peroxide (H
2O
2)) to obtain Iodine.
2 KI + 2 HCl -> 2 HI + 2 KCl
2 HI + H
2O
2 -> I
2 + 2 H2O
The Iodine salt whithin the tincture has to be oxidised to obtain I
2.
This equation is a stab in the dark. Is this the reaction? Could somebody correct me?
2 I + 4 H
2O
2 -> I
2 + 2 H
2O + O
2If the contents of a 1L bottle of tincture contained:
25mg/mL Iodine
25mg/mL Potassium Iodide
Ethanol
I assume the following parameters would have to be met.
mol = weight of sample (g) / molar weight (g/mol)
mol = 25g KI contained in bottle / 166.02g/mol
mol = 0.151mol KI
KI + HCl -> HI + KCl
0.151mol KI + 0.151mol HCl -> 0.151mol HI + 0.151mol KCl
25g KI + 4.14mg HCl -> 1.18mg HI + 2.03mg KCl
When performing this reaction adequate H
2O should be present as to dissolve the HI as it is formed.
2 HI + H
2O
2 -> I
2 + 2 H
2O
0.151mol HI + 0.0755mol H
2O
2 -> 0.0755mol I
2 + 0.151mol H
2O
1.18mg HI + 2.22mg H
2O
2 -> 0.595mg I
2 + 8.39mg H
2O
Once these reactions have completed the I
2 should fall out of the solution because iodine is immiscible in water.
Swim has left the last equation as it is probably incorrect. But there is still another 25g of iodine salt contained in the tincture.
Questions.
Wouldn't the iodine salt in the tincture also be liberated once the iodine from the KI has been obtained?
Swim asks this because of this statement.
"Iodine is soluble in a solution of potassium iodide due to the formation of the soluble potassium tri-iodide."
Found at
http://www.ucc.ie/ucc/depts/chem/dolchem/html/elem/elem053.html
Is the oxidation of I into I
2 necessary as my understanding of elemental Iodine is that it is already in I
2 form? (diatomic?
)
Would the ethanol in the tincture change the reaction(s) in any way?
This whole post is up for scrutiny. Swim just wishes to understand what the hell is going on. Feel free to flame away or provide some helpful insight.