Which technique is used to separate the components of a liquid mixture by boiling point differences?

• A. Chromatography
• B. Filtration
• C. Distillation
• D. Crystallization

Answer: (C)

Distillation uses differences in boiling points to separate components. When a liquid mixture is heated, the component with the lower boiling point tends to vaporize first. The vapor is then cooled in a condenser and collected as a separate liquid, leaving the higher-boiling-point components behind. If the boiling points are similar, a fractionating column provides more surface area for repeated evaporation and condensation, improving separation.

This approach specifically exploits vapor pressure differences rather than solubility, particle size, or crystal formation, which is why it’s the method of choice for purifying liquids or separating liquid mixtures like water and ethanol. If boiling points are very close or form an azeotrope, simple distillation may not fully separate them, and more advanced techniques may be needed.