In liquid extraction, the two phases are commonly called the extract phase and the _______.

• A. Raffinate
• B. Dispersed phase
• C. Solvate
• D. Equilibrate

Answer: (A)

In liquid-liquid extraction, the labeling follows the role of each phase after contact: the phase that takes up most of the solute becomes the extract phase, while the other immiscible liquid is called the raffinate. This naming makes it easy to write mass balances and define relationships like the distribution coefficient, which is the ratio of the solute concentration in the extract to that in the raffinate. The other terms don’t fit as well: a dispersed phase is a general way to describe droplets in an emulsion, not the standard name for the nonextract phase; solvate is a chemical term for a solute–solvent complex, not a phase name; equilibrate is a verb describing reaching equilibrium, not a phase designation.