53. Fractional Distillation of Crude Oil

Based on the video, here are the notes on what crude oil is and how it is separated into useful components.

Composition: A complex mixture of many different compounds, nearly all of which are hydrocarbons (mostly alkanes).
Formation: Formed naturally from the remains of dead plants and animals (mainly plankton) that died millions of years ago. High pressures and temperatures underground turned this biomass into oil.
Resource Type: It is a finite (non-renewable) resource. Once we use it all, it will take millions of years to replace.

Since the hydrocarbons in crude oil have different properties, we use fractional distillation to separate them based on their boiling points.

Step 1: Heating: The crude oil is heated until most of it turns into a gas.
Step 2: The Column: The gaseous mixture enters a fractionating column, which is hot at the bottom and gradually becomes cooler toward the top.
Step 3: Condensation:
- As the gases rise, they condense into liquids once they reach a region cooler than their boiling point.
- Long-chain hydrocarbons: Have high boiling points. They condense and drain out near the bottom early on (e.g., bitumen, heavy fuel oil).
- Short-chain hydrocarbons: Have lower boiling points. They rise higher and condense near the top (e.g., petrol, kerosene).
- Very short chains: Some stay as gases the entire time and leave from the very top (e.g., LPG/propane/butane).

The different "fractions" separated during this process have distinct uses:

Top (Short chains): Highly flammable, making them the best fuels (LPG, Petrol, Diesel).
Bottom (Long chains): Poor fuels; used for other purposes like surfacing roads (bitumen) or broken down into smaller molecules via "cracking."
Petrochemicals: These substances act as feedstock (raw materials) to create everyday products like solvents, lubricants, polymers (plastics), and detergents.