Question

Which separation technique will you apply for the separation of the following mixture?

Benzene from a mixture of benzene and methylbenzene

Answer 1

The separation technique applied for the separation of Benzene $\left({\mathrm{C}}_6{\mathrm{H}}_6\right)$ and Toluene or Methyl benzene $\left({\mathrm{C}}_7{\mathrm{H}}_9\right)$ is fractional distillation.

Fractional distillation: It is a technique for the separation of a mixture of two miscible liquids which have comparable boiling points or the difference between their boiling points is less than 25 K.

Boiling point of benzene is $80°\mathrm{C}$ and the boiling point of toluene is$110°\mathrm{C}$.

Principle involved in the separation of mixture:

• The component with a lower boiling point evaporates first and leaves the mixture due to the difference in the boiling points.
• As the difference in their boiling points is comparable, so the vapours of the other liquid are cooled in the fractionating column and condensed back to the flask.
• Miscible liquids: A mixture of two or more liquids which mix with each other to form a homogeneous solution. Example: a mixture of ethanol and water