[slutsavenue]

Iodine is sparingly soluble in water but much more so in carbon tetrachloride (CCl4). The equilibrium constant, also called the partition coefficent, for the distribution of I2 between these two phases

I2 (aq) ⇋ I2 (CCl4)

is 83 at 20°C. A student adds 0.030 L of CCl4 to 0.200 L of an aqueous solution containing 0.032 g I2. The mixture is shaken and the two phases are then allowed to separate. Calculate the fraction of I2 remaining in the aqueous phase.

The given answer is 0.075. I have no idea how to derive the fraction of I2.

[Borek]

It is not much different from any other equilibrium problem. First, write equation for the partition coefficient. Second, write equation for the mass balance. That will yield two equations in two unknowns.