Practice Problem 2

The iodide ion reacts with iodine in aqueous solution to form the I3-, or triiodide, ion.

I-(aq) + I2(aq) I3-(aq)

What would happen if CCl4 was added to an aqueous solution that contained a mixture of KI, I2, and KI3?


KI and KI3 are both salts. One contains the K+ and I- ions; the other contains the K+ and I3- ions. These salts are more soluble in polar solvents, such as water, than in nonpolar solvents, such as CCl4. KI and KI3 would therefore remain in the aqueous solution. I2 is a nonpolar molecule, which is more soluble in a nonpolar solvent, such as carbon tetrachloride. The I2 would therefore leave the aqueous layer and enter the CCl4 layer, where it would exhibit the characteristic violet color of solutions of molecular iodine.