Question

Why do phospholipids form a bilayer in water?

Answer 1

When phospholipids are mixed withwater, they spontaneously rearrange themselves to form the lowest free-energy configuration. This means that the hydrophobic regions find ways to remove themselves from water, while the hydrophilic regions interact withwater. The resulting structure is called a lipid bilayer.

Answer 2

On mixing phospholipids with water, they spontaneously rearrange themselves.

They then form the lowest free energy configuration.

This implies that :

The hydrophobic regions find ways to remove themselves from water whereas the hydrophilic regions  interact with water.

The resulting structure is called a lipid bilayer.