Liquid-Liquid Extraction: Enhancing Efficiency Through Shaking

What is the purpose of shaking the separatory funnel during liquid-liquid extraction?

(a) Does shaking the separatory funnel change the partition coefficient?

Answer:

(a) No, shaking the separatory funnel does not change the partition coefficient. The partition coefficient is a constant value that describes the distribution of a solute between two immiscible phases. It is determined by the relative solubilities of the solute in the two phases and is unaffected by shaking.

When performing liquid-liquid extraction, shaking the separatory funnel does not change the partition coefficient. However, shaking increases the surface area between the two immiscible liquids, which enhances the transfer of the solute between the phases. This results in a more efficient extraction process.

The purpose of shaking the funnel is to facilitate the solute's distribution between the two phases, which is based on the principle of the partition coefficient. The partition coefficient is an equilibrium constant that describes how a solute distributes itself between two immiscible solvents at equilibrium and is not altered by shaking. Shaking simply speeds up the attainment of this equilibrium. In an automated system that performs numerous sequential extractions, shaking (or stirring in automated devices) is mimicked to continually disrupt equilibrium, leading to a product of higher purity by applying the Le Chatelier principle.