1. The Principle
Fractional distillation relies on the difference in boiling points of the two liquids. Petrol (gasoline) has a lower boiling point than kerosene. This means that petrol will vaporize (turn into a gas) at a lower temperature than kerosene.
2. The Setup
* Fractional Distillation Column: A tall, vertical column with many trays or plates.
* Heating Source: A source to heat the mixture (e.g., a Bunsen burner).
* Condenser: A device to cool the vapors and convert them back into liquid.
* Collection Vessels: Separate containers to collect the distilled fractions.
3. The Process
1. Heating: The mixture of petrol and kerosene is heated in a flask at the bottom of the column.
2. Vaporization: As the mixture is heated, the petrol with its lower boiling point starts to vaporize first.
3. Ascending Vapors: The petrol vapors travel up the fractional distillation column.
4. Condensation: As the vapors rise, they encounter cooler temperatures on the trays of the column. The vapors of the lower boiling point (petrol) will condense at higher levels in the column, while the vapors of the higher boiling point (kerosene) will condense at lower levels.
5. Collection: The condensed petrol is collected separately from the condensed kerosene.
Why a Tall Column?
The tall column provides more surface area and allows for multiple condensation-evaporation cycles. This ensures a more efficient separation, as the vapors of the higher boiling point liquid (kerosene) continue to condense and fall back down, while the vapors of the lower boiling point liquid (petrol) continue to rise.
Key Points:
* The difference in boiling points between petrol and kerosene (25°C) is sufficient for effective separation using fractional distillation.
* The efficiency of the separation depends on the column's height, number of trays, and the temperature gradient maintained.
* Fractional distillation is a common method used in the petroleum industry to separate crude oil into various fractions.
Important Note: Fractional distillation of flammable liquids like petrol and kerosene should be carried out in a controlled environment with proper safety measures in place.
