What is fractional distillation used for in industry? Explain the molecular basis behind it.

Separating different sized hydrocarbons (from crude oil)Different length hydrocarbons have different strength VDW forces between their moleculesTherefore longer length hydrocarbons have stronger VDW forces between their moleculesTherefore longer hydrocarbons have higher boiling pointsAllows hydrocarbons to be separated based on boiling point; different length hydrocarbons will condense at different temperature fractions, separating them from one another