Fractional distillation is a technique used to separate complex mixtures of hydrocarbons based on differences in their

1. heats of fusion
2. heats of vaporization
3. melting points
4. boiling points

based on differences in their boiling points.

boiling points

4. boiling points

The correct answer is 4. boiling points.

Fractional distillation is a technique used to separate complex mixtures of hydrocarbons based on the differences in their boiling points. The process takes advantage of the fact that different substances have different boiling points, and by carefully controlling the temperature, it becomes possible to separate the components of a mixture.

Here's how fractional distillation works:

1. The mixture of hydrocarbons is heated in a distillation apparatus.
2. As the mixture is heated, the hydrocarbons with lower boiling points will start to vaporize first.
3. The vapor rises through a fractionating column, which is a vertical tube packed with materials like glass beads or metal plates. This column provides a larger surface area for the vapor to condense and provides more opportunities for separation.
4. As the vapor rises through the column, it cools down. The substances with lower boiling points will have already condensed and can be collected separately.
5. The substances with higher boiling points will continue to rise in the column until they reach their respective condensation points and are collected separately at different heights in the column.
6. The collected fractions can then be further processed or used as desired.

By separating the hydrocarbons based on differences in boiling points, fractional distillation allows for the efficient separation of complex mixtures. The process is widely used in the petroleum industry to refine crude oil into various useful products like gasoline, diesel, and jet fuel.