Mixing Oil and Water
Immiscibility & Emulsifiers
Explore why oil and water don't mix and how emulsifiers like soap or egg yolk can help combine them. Try shaking the mixture and adding different emulsifiers to see the effects!
Observation:
Oil and water naturally separate into distinct layers because they are immiscible.
The Science Behind Oil and Water
Why Don't They Mix?
Oil (nonpolar) and water (polar) have different molecular structures:
- Water molecules are polar and form hydrogen bonds
- Oil molecules are nonpolar and only have weak London dispersion forces
- The water molecules "prefer" to stick to other water molecules
Emulsifiers to the Rescue:
Emulsifiers have molecules with both polar and nonpolar parts:
- Soap: Polar head (hydrophilic) and nonpolar tail (hydrophobic)
- Egg yolk (lecithin): Similarly has both hydrophilic and hydrophobic parts
- They position themselves at the oil-water interface, allowing temporary mixing
Real-world Examples:
Emulsifiers are used in mayonnaise (egg yolk), salad dressings, lotions, and many processed foods.
