How is crude oil separated into fractions at refin
The boiling point of a hydrocarbon depends on the size of its molecules. The larger the molecule, the higher the boiling point of the hydrocarbon. Crude oil is vaporised & fed into a fractioning columns. The hydrocarbons condense when they reach the level that is at their boiling point, the levels have outlets to collect the fractions. Hydrocarbons with smallest molecules @ top of column, largest @ bottom (with highest points).