Iodine, is slightly soluble in H2O, but quite soluble in a nonpolar solvent like tolune.?

Question

What can you tell about the nature of the iodine molecule? Could it be ionic, polar or nonpolar?

Answer 1

It is nonpolar, but there's an interesting fact about its solutions. In the nonpolar solvent toluene, its solution will be purple, but in alcohol or water, it forms a brown solution. It will also dissolve much more readily in an aqueous solution of potassium iodide (KI) than in plain water, because it forms ions like I₃⁻, I₅⁻, and I₇⁻.

The nonpolar solvent has no electronic effect on the iodine molecule (I₂), so its color is similar to that of its gaseous phase. Polar solvents tend to polarize the relatively weak I-I bond through interactions like H₂O----I----I----H-OH, so that the atom interacting with the O atom tends to loosen its hold on the bonding electrons, while the one interacting with the H atom tends to pull the electron charge to itself. This polarizing effect causes the color change. Distributing the charge from the I⁻ ion among 3, 5, or 7 atoms similarly changes the behavior from that in a nonpolarizing environment.

Answer 2

The iodine molecule is nonpolar. It is a dimer, where the two iodine atoms contribute one electron each to a bond.

Answer 3

Toluene is a nonpolar substance and since iodine is also nonpolar, it will be more soluble in it. Just remember that "like" dissolves "like".