Deep Dive: What's in Crude Oil?

🔬 Deep Dive: What's in Crude Oil?

Crude oil is a mixture of hydrocarbons:

• Hydrocarbons = molecules made of hydrogen and carbon ONLY
• Most are alkanes (saturated hydrocarbons with single C-C bonds)
• The mixture contains molecules of many different sizes
• It's a finite resource — once it's gone, it's gone (takes millions of years to form)

How Crude Oil Formed:

1. Millions of years ago, tiny sea creatures (plankton) died and sank to the seabed
2. Layers of sediment buried them, cutting off oxygen
3. Heat and pressure over millions of years converted them to crude oil
4. This is why it's called a fossil fuel

Fractional Distillation — The Separation Process:

1. Crude oil is heated to about 350°C — everything vaporises
2. Hot vapour enters the bottom of a tall fractionating column
3. Column is hot at bottom, cool at top (temperature gradient)
4. As vapour rises, it cools. When a fraction reaches its boiling point, it condenses
5. Different fractions collected at different heights

Why It Works: This is a physical process — no chemical bonds are broken. We're just separating molecules by their boiling points. Larger molecules have higher boiling points (stronger forces between molecules to overcome).