Oil and Water Emulsification
Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★★☆ Some safety precautions required to perform safely
Categories: Water and Solubility
Alternative titles: Soap as an Emulsifier
Summary
Oil and water normally separate into layers, but adding soap or detergent allows them to mix temporarily. This demonstrates how emulsifiers work by suspending oil droplets in water.
Procedure
Fill a clear glass or flask with some water.
Add oil (or kerosene) to the water and swirl gently. Observe how the two liquids separate into layers.
Add a squirt of dishwashing detergent or liquid soap.
Swirl or shake the flask again and observe how the oil breaks into droplets suspended throughout the water.
(Optional) Add food coloring to color the water for easier visualization.
Links
Variations
Use different types of oil (vegetable, olive, mineral) and compare results.
Try natural emulsifiers such as egg yolk or mustard instead of dish soap.
Safety Precautions
If using kerosene, conduct the demonstration in a well-ventilated area and keep it away from flames or sparks.
Do not drink or taste any materials used.
Wash hands after handling oils, kerosene, or soap.
Clean up spills promptly to avoid slipping hazards.
Questions to Consider
Why don’t oil and water normally mix? (Oil is nonpolar while water is polar, so they are immiscible.)
How does soap act as an emulsifier? (Soap molecules have both polar and nonpolar ends, allowing them to interact with both oil and water.)
Why do oil droplets remain suspended after soap is added? (The soap molecules surround the droplets, preventing them from clumping back together.)
What role do emulsifiers play in everyday life? (They help make foods like mayonnaise, salad dressings, and ice cream, and aid cleaning by suspending oils and dirt in water.)