During fractional distillation, the crude oil is heated at the base of the column until vapour is formed. Say whether the vapour contains more or less than the more volatile hydrocarbons.

Then, explain how this process is used to separate the fractions of crude oil.

Vapour contains more? Not sure why and how to explain.
Heating and mixing?

For any help given, thanks in advance!

1 answer

http://en.wikipedia.org/wiki/Fractional_distillation