Colors of iodine solutions in water, ethanol, KI (aq) and hexane. Sublimation and starch reaction.

How solid iodine looks and how it sublimes, solutions of iodine in water, ethanol, potassium iodide and hexane.
Explanations are accompanied by high-quality photos.

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The colors of iodine:
solid - shiny grey-black
vapor - purple
solution in water - virtually not soluble, yellow or pale brown
in ethanol - brown
in KI(aq) - brown
in hexane - purple
with soluble starch - blue-black

Iodine is not soluble in water as its molecules are nonpolar. It is soluble in ethanol (due to interaction with its nonpolar ethyl group). It is soluble in hexane (which is nonpolar).
It is soluble in aqueous KI due to formation of complexes between iodine molecules and iodide ions.

Iodine reversibly reacts with soluble starch forming deep blue color. In iodine redox titrations soluble starch is added when iodine solution pales to straw color to emphasize the end-point, at which the solution titrated changes from blue to colorless.

Chapters:
00:00 Solid iodine appearance
00:22 Gaseous iodine in equilibrium with solid
00:42 Sublimation of iodine
01:07 Solubility of iodine in water
01:43 Solubility of iodine in ethanol
02:13 Solubility of iodine in iodide solutions (KI (aq))
02:57 Solution of iodine in hexane (in alkanes)
03:21 Distribution of iodine in layers of hexane and KI (aq); solvent extraction
04:10 Overview of solutions of iodine in different solvents
04:30 Iodine and starch reaction
05:09 Main points of the video revisited