Overview
This lecture explains what crude oil is, how it is formed, and describes the process of fractional distillation to separate its components.
Crude Oil: Formation and Source
- Crude oil is a fossil fuel found deep underground, formed from dead plants and animals (mainly plankton) over millions of years.
- It consists mostly of hydrocarbons, particularly alkanes (compounds containing only hydrogen and carbon).
- Crude oil is non-renewable, meaning it will eventually run out if consumption continues at the current rate.
Fractional Distillation Process
- Fractional distillation separates crude oil into different hydrocarbons based on their boiling points.
- Crude oil is heated until most becomes a gas and then passed into a fractionating column.
- The column is hottest at the bottom and cooler at the top.
- Hydrocarbons condense back into a liquid when they reach a region cooler than their boiling point.
Fractions and Their Uses
- Long-chain hydrocarbons (high boiling points) condense at the bottom, producing substances like bitumen and heavy fuel oil.
- Shorter-chain hydrocarbons (lower boiling points) rise higher and condense higher up, producing diesel, petrol, and kerosene.
- Very short-chain hydrocarbons (like propane and butane in LPG) may remain as gases.
- Shorter-chain fractions are more flammable and make better fuels.
- Longer-chain hydrocarbons are often used for other purposes or broken down further by cracking.
Petrochemicals and Their Applications
- Petrochemicals are all substances obtained from crude oil fractions.
- They are used as feedstock to make solvents, lubricants, polymers, and detergents.
Key Terms & Definitions
- Crude Oil — Unprocessed oil extracted from the ground, mainly a mixture of hydrocarbons.
- Hydrocarbons — Chemical compounds made exclusively of hydrogen and carbon.
- Alkanes — Saturated hydrocarbons with only single bonds between carbon atoms.
- Fractional Distillation — A process that separates substances in a mixture using differences in their boiling points.
- Fractionating Column — The equipment used for separating vapors during fractional distillation.
- Fractions — The different hydrocarbon groups collected at various levels in the fractional distillation column.
- Petrochemicals — Chemicals derived from crude oil used as raw materials in industry.
- Feedstock — Raw material supplied to a process for conversion into products.
Action Items / Next Steps
- Review the process of cracking of hydrocarbons, which will be covered in the next lesson.