IGCSE Chemistry Practice Exam 2026 – Complete Study Resource

Fractional distillation is a technique used to separate a mixture of liquids based on their different boiling points. When a mixture is heated, the component with the lowest boiling point vaporizes first. This vapor is then allowed to rise through a fractionating column, where it cools and condenses back into a liquid at various heights, depending on the temperature. As the temperature changes along the column, other components with higher boiling points can also vaporize, but they will do so at different temperatures. This process effectively separates the liquids, allowing them to be collected individually at different levels of the column or through separate collection containers.

In contrast to fractional distillation, using a water bath typically serves as a means to control temperature in certain laboratory experiments, but it does not inherently separate liquids by boiling point. Cooling the mixture may lead to condensation, but it would not effectively separate the differing boiling points of the liquids. Lastly, dissolving in water is not applicable to distillation, as it pertains to separating solids or miscible liquids rather than utilizing boiling points for resolution. Thus, the principle of using different boiling points is what makes fractional distillation an effective separation technique for liquid mixtures.