Ohio Assessment for Educators (OAE) Integrated Science (024) Practice Exam

Which method is used to separate a liquid mixture into fractions according to boiling point?

1. Filtration

2. Paper chromatography

3. Fractional distillation

4. Evaporation

The correct answer is: Fractional distillation

Fractional distillation is the method employed to separate a liquid mixture into its constituent fractions based on their different boiling points. This technique is particularly effective when dealing with mixtures of liquids that have close boiling point ranges. In fractional distillation, the mixture is heated, causing the components with lower boiling points to vaporize first. The vapor then passes through a fractionating column, where it cools and condenses back into a liquid upon reaching a cooler area in the column. This process allows the liquid to be collected in fractions as they condense at different temperature points, effectively separating the various components of the mixture. The efficiency of fractional distillation is enhanced by the many theoretical plates created within the fractionating column, allowing for multiple vaporization and condensation steps that lead to higher purity of the separated fractions. This method is widely used in industries, such as petroleum refining and chemical manufacturing, where separation of various solvents and components is necessary. Other methods mentioned, such as filtration, paper chromatography, and evaporation, serve different purposes. Filtration is used to separate solids from liquids, chromatography is for separating components based on their movement through a medium, and evaporation is a technique primarily for removing a solvent from a solution, rather than separating multiple liquid components based on