When should you attempt to extract a solution?

• A. When it is hotter than the boiling point of the extractant
• B. Immediately after mixing
• C. When it is cooler than the boiling point of the extractant
• D. Never

Answer: (C)

Extraction works best when the extractant remains a liquid and forms a separate, immiscible phase. If you try to extract while the mixture is hotter than the extractant’s boiling point, the extractant begins to vaporize, leading to loss of solvent, potential fumes, and poorer control of the two-phase system. Immediate extraction after mixing often catches the system before the layers have properly separated and reached equilibrium, giving inefficient transfer of solute. When the mixture is cooler than the extractant’s boiling point, the extractant stays liquid, the two phases separate cleanly, and the solute partitions into the extractant more reliably. So, you should attempt extraction once the mixture is cooler than the extractant’s boiling point and the phases have had time to separate.