Answer:
K = 4.00
Step-by-step explanation:
The partition is equal to the concentration of the solute in phase 2 (hexane) divided by the concentration of the solute in phase 1 (water)
K = [S]₂ / [S]₁
The concentration is in moles per liter, so first we must find the number of moles of the solute that remained in the aqueous phase:
(12.0 mg)(mol/84.0 g) = 0.142857 mmol in phase 1
Additional significant figures are kept to avoid round-off errors.
We calculate the concentration in phase 1 by dividing by the volume:
[S]₁ = n/V = (0.142857 mmol) / (10.0 mL) = 0.0142857 mol/L
Next, we calculate the number of moles that were extracted into the organic phase:
(36.0 mg - 12.0 mg)(mol/84.0g) = 0.285714 mmol in phase 2
Similary, we divide by the volume to get the concentration:
[S]₂ = n/V = (0.285714 mmol) / (5.0 mL) = 0.0571428 mol/L
Finally, we can calculate the partition coefficient:
K = [S]₂ / [S]₁ = (0.0571428 mol/L) / (0.0142857 mol/L)
K = 4.00