Distillation & Floatation: Videos & Practice Problems

Simple distillation and fractional distillation are both techniques used to separate components of a mixture based on differences in boiling points. Simple distillation is effective when the boiling point difference between the components is greater than 25°C. It involves heating the mixture to vaporize the component with the lower boiling point, which is then condensed and collected. Fractional distillation, on the other hand, is used when the boiling point difference is less than 25°C. It includes a fractional column filled with beads that provide a larger surface area for repeated vaporization and condensation cycles, resulting in a purer product. While simple distillation is faster and yields a larger amount of product, fractional distillation produces a more refined and pure filtrate.

Fractional distillation works by exploiting the differences in boiling points of the components in a mixture. The process involves heating the mixture to vaporize the component with the lower boiling point. The vapor then travels up a fractional column filled with beads, which provide a large surface area for repeated cycles of vaporization and condensation. As the vapor ascends the column, it undergoes multiple condensation and re-vaporization steps, which help to separate the components more effectively. The vapor eventually reaches a Liebig condenser, where it is cooled and condensed back into a liquid, resulting in a purer product. This method is particularly useful for separating components with boiling point differences of less than 25°C.

Simple distillation should be used when the boiling point difference between the components of the mixture is greater than 25°C. This method is faster and yields a larger amount of product, although it may not be as pure as the product obtained from fractional distillation. Simple distillation is ideal for separating mixtures where the components have significantly different boiling points, such as methanol (67°C) and water (100°C). If the boiling point difference is less than 25°C, fractional distillation is recommended, as it provides a purer product through repeated cycles of vaporization and condensation.

The main components of a distillation apparatus include a heat source (such as a Bunsen burner or hot plate), a distillation flask containing the mixture, a thermometer to monitor the temperature, a condenser (such as a Liebig condenser) to cool and condense the vapor, and a receiving flask to collect the distilled liquid. In fractional distillation, an additional component called a fractional column is used. This column is filled with beads that provide a large surface area for repeated vaporization and condensation cycles, enhancing the separation of components with close boiling points.

Fractional distillation is more effective for separating components with close boiling points because it includes a fractional column filled with beads. These beads provide a large surface area for repeated cycles of vaporization and condensation. As the vapor ascends the column, it undergoes multiple condensation and re-vaporization steps, which help to separate the components more effectively. This process increases the number of theoretical plates, enhancing the separation efficiency and resulting in a purer product. Simple distillation, lacking this column, cannot achieve the same level of separation for components with close boiling points.