Describe and explain how the mixture of alkanes is seperated by fractional distillation?

Alkanes in distillation are separated on the basis of their boiling points. The boiling point is dependant upon the number of carbons present. For example methane and ethane differ by one CH2 unit therefore the boiling point of ethane will be higher than methane as more energy is required to evaporate ethane than methane.

Each carbon usually increases the boiling point by about 30-40C. So in terms of distillation methane will reach its boiling point at lower temperatures than ethane so will evaporate and can be separated. Fractional distillation only differs from normal distillation as it contains a fraction column which allows for efficient separation of compounds with closely related boiling like the alkanes. Within the column the compound constantly condenses and evaporates which allows for a more efficient and accurate separation.