SCIENTIFIC INFORMATION
Elemental diatomic iodine forms I- anions in solution with water, which is very poorly soluable. The addition of a highly soluble iodide, such as potassium iodide, allows the diatomic molecule of iodine (I2) to combine with the I- anion of the potassium iodide to form the I3- ion, which is highly soluble in water, thus allowing the elemental iodine to dissolve.