60. A student decided to perform liquid-liquid extraction of solute A and solute B separately. Based
on the table below, indicate which of the following options is CORRECT about their partition coefficient
(K)?
Solute A                                                                    Solute B
Concentration of solute in extract                          (g/L) 50 1
Concentration of solute in raffinate                      (g/L) 1 50
1.𝐾𝐴 = 𝐾𝐵
2. 𝐾𝐴 > 𝐾𝐵
3. 𝐾𝐴 < 𝐾𝐵
4. 𝐾 cannot be determined with the given information

Understanding Partition Coefficient (K) in Liquid-Liquid Extraction

Liquid-liquid extraction is a crucial technique in chemical and biochemical processes. It relies on the partitioning of solutes between two immiscible liquid phases. The efficiency of extraction is determined by the partition coefficient (K), which represents the ratio of a solute’s concentration in the extract to its concentration in the raffinate.

How to Calculate the Partition Coefficient (K)?

The partition coefficient (K) is defined as:

k=  C extract/C raffinate

where:

• Cextract = Concentration of solute in the extract (g/L)
• Craffinate = Concentration of solute in the raffinate (g/L)

For the given data:

Solute A:

KA= 50/1

=50

Solute B:

KB=1/50

=0.2

Since

KA is 50 and KB IS 0.2

so  KA>KB

 

This means solute A is more efficiently extracted into the extract phase compared to solute B.

What Does a Higher Partition Coefficient Indicate?

• A high K value (e.g., solute A) indicates that the solute prefers the extract phase.
• A low K value (e.g., solute B) suggests that the solute remains mostly in the raffinate.

Factors Affecting Partition Coefficient (K)

Several factors influence the partitioning of solutes in liquid-liquid extraction:

1. Solvent Polarity

• Polar solutes dissolve better in polar solvents (e.g., water).
• Non-polar solutes dissolve better in non-polar solvents (e.g., organic solvents like hexane).

2. Temperature

• Higher temperatures can alter solubility and affect extraction efficiency.

3. pH of the Aqueous Phase

• Ionizable compounds (e.g., acids, bases) may shift their distribution depending on pH.

4. Molecular Size and Structure

• Larger molecules with hydrophobic regions tend to prefer organic solvents.

Applications of Liquid-Liquid Extraction

• Pharmaceutical Industry: Separation of drugs and active compounds.
• Environmental Science: Removal of pollutants from wastewater.
• Biotechnology: Isolation of biomolecules like antibiotics and enzymes.
• Petrochemical Industry: Extraction of valuable hydrocarbons.

Conclusion

By applying the partition coefficient formula, we determined that , making option 2 the correct answer. Understanding the factors affecting K helps in optimizing liquid-liquid extraction processes for efficient separation and purification of solutes.