Elemental iodine is soluble in water, but only slightly. One gram of iodine dissolves in 3,450 milliliters at 20 degrees Celsius. To increase solubility, potassium iodide can be added, as well as nonpolar solvents, such as carbon tetrachloride and hexane.
Iodine is blue-black solid that normally exists as a diatomic molecule. It is naturally present in water. Iodine can be found in water due to rain and water evaporation. The average iodine concentration in seawater is around 60 parts per a billion. The average concentration in rivers is 5 parts per a billion. Iodine forms compounds with all of the elements, with the exception of the noble gases.