What is the key feature that differentiates fractional distillation from simple distillation?

Fractional distillation is distinguished from simple distillation primarily by the addition of a fractionating column. This column enhances the separation of components in a mixture based on their boiling points.

In fractional distillation, the fractionating column provides a larger surface area for multiple condensation and evaporation cycles as the vapor rises through the column. As this vapor encounters cooler surfaces, it condenses, and then evaporates again when it encounters heat. This process allows for greater refinement and separation between components in a mixture with closer boiling points.

In contrast, simple distillation does not utilize a fractionating column and is effective only when separating components with significant differences in their boiling points. The absence of a fractionating column in simple distillation restricts the ability to separate components that have similar boiling points effectively.

Therefore, the addition of a fractionating column is a crucial feature that enables fractional distillation to achieve higher purity of distillates compared to simple distillation.