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Matter & Chemistry Hall · EXH-0010
Why do oil and water form layers?
Shaking makes many droplets for a while, then two broad layers return.
Start the experience01
What should you look for?
What changed between stirring and waiting?
- 01Stirring made smaller droplets
- 02Droplets joined again while waiting
- 03A surfactant kept smaller droplets apart longer
02
Why does this happen?
Molecular attractions differ
Water molecules strongly attract one another, while oil-like molecules interact differently, so the two liquids do not readily make one uniform phase.
Density helps order the layers
In this chosen pair, the model oil is less dense and settles above water. Other liquids can have different density orders.
This qualitative model uses one water–oil pair. It does not claim every oil is lighter than every water-based liquid.
03
Move it before reading the answer
Use fixed amounts of water and model oil. After the first separation, try the surfactant extension.