Question

Suppose 35 mg of benzoic acid is dissolved in 7 mL of dichloromethane. The resulting organic solution is then extracted with

12 mL of water. It is determined that the dicholoromethane layer now contains 31 mg of benzoic acid.
What is the partition coefficient (Kp) of benzoic acid in dichloromethane/water?

Answer 1

Kp = 13.3

Step-by-step explanation:

Partition coefficient is used to extract or purify a solute from a solvent selectively to avoid interference from other substances. The formula is:

Kp = Concentration of solute in organic solvent / Concentration of solute in H₂O

As the CH₂Cl₂ is containing 31mg, water is containing 4mg. Replacing in the formula:

Kp = (31mg/7mL) / (4mg/12mL)

Kp = 13.3