In a very controlled experiment, a student is sure that 0.500 grams of caffeine is dissolved in 125 mL of water. The student extracts the caffeine using a single extraction of 21 mL of methylene chloride. How much caffeine is in the methylene chloride? How much remains in the water?

Answer 1

I assume you know K for this.
K = (x/21)/(0.5-x)/125]
x = g in methylene chloride
0.5-x = g caffeine in water layer.