Iodine is sparingly soluble in water but much more so in

Chapter 15, Problem 126AP

(choose chapter or problem)

Iodine is sparingly soluble in water but much more so in carbon tetrachloride \(\left(\mathrm{CCl}_4\right)\). The equilibrium constant, also called the partition coefficient, for the distribution of \(\mathrm{I}_2\) between these two phases

\(\mathrm{I}_2(a q) \rightleftarrows \mathrm{I}_2\left(\mathrm{CCl}_4\right)\)

is 83 at \(20^{\circ} \mathrm{C}\).

(a) A student adds \(0.030 \mathrm{~L}\) of \(\mathrm{CCl}_4\) to \(0.200 \mathrm{~L}\) of an aqueous solution containing \(0.032 \mathrm{~g}\) of \(\mathrm{I}_2\). The mixture at \(20^{\circ} \mathrm{C}\) is shaken, and the two phases are then allowed to separate. Calculate the fraction of \(\mathrm{I}_2\) remaining in the aqueous phase.

(b) The student now repeats the extraction of \(\mathrm{I}_2\) with another \(0.030 \mathrm{~L}\) of \(\mathrm{CCl}_4\). Calculate the fraction of the \(\mathrm{I}_2\) from the original solution that remains in the aqueous phase.

(c) Compare the result in part (b) with a single extraction using \(0.060 \mathrm{~L}\) of \(\mathrm{CCl}_4\). Comment on the difference.