Overview
This lecture explains how crude oil is separated into its components using fractional distillation, and discusses the uses of the resulting products.
Crude Oil: Origin and Composition
- Crude oil is a fossil fuel formed from ancient dead plants and animals, mainly plankton, buried under mud for millions of years.
- High pressure and temperature transformed the organic material into crude oil.
- Crude oil is stored in rocks underground and extracted by drilling.
- It is a finite, non-renewable resource; continued extraction will eventually exhaust it.
- Crude oil is a mixture mainly composed of hydrocarbons, especially alkanes (compounds with only hydrogen and carbon).
Fractional Distillation Process
- Fractional distillation separates crude oil into different hydrocarbons based on boiling points.
- Crude oil is heated so most of it vaporizes and is fed into a fractionating column.
- The column is hottest at the bottom and cooler at the top; gases rise and condense at different heights depending on their boiling points.
- Long-chain hydrocarbons have high boiling points, condense early, and drain from the column near the bottom.
- Short-chain hydrocarbons have low boiling points, rise higher before condensing.
Uses of Different Fractions
- Bottom fractions (long chains): Bitumen (road surfacing), heavy fuel oil (heating, lubricants).
- Middle fractions: Diesel, petrol (vehicles), kerosene (jet engines).
- Top fractions (shortest chains): LPG (liquefied petroleum gas, e.g., propane and butane) stays gaseous.
- Shorter chains are more flammable and make better fuels.
- Longer chains are less useful as fuels but can be broken down into smaller ones in a process called cracking.
Petrochemical Industry Uses
- Substances obtained from crude oil are called petrochemicals.
- Petrochemicals serve as feedstock (raw materials) for producing solvents, lubricants, polymers, and detergents.
Key Terms & Definitions
- Crude Oil — A mixture of hydrocarbons found underground, formed from ancient biomass.
- Hydrocarbons — Compounds containing only hydrogen and carbon.
- Alkanes — A type of hydrocarbon with single bonds only.
- Fractional Distillation — Process that separates mixtures by boiling points.
- Fractionating Column — Equipment used to separate vaporized crude oil into fractions.
- Bitumen — Thick, heavy fraction used for road surfaces.
- LPG (Liquefied Petroleum Gas) — Gaseous hydrocarbon mixture mainly of propane and butane.
- Feedstock — Raw materials used in industrial processes.
- Cracking — Process of breaking long-chain hydrocarbons into shorter ones.
Action Items / Next Steps
- Review how fractional distillation operates and why boiling points are important.
- Prepare for the next lesson on the cracking process.