Why are lipids insoluble in water?

Question

Why are lipids insoluble in water?

Answer 1

Something is soluble in water if water molecules can latch onto molecules of the substance and pull the molecules apart by wriggling between the molecules.

Water is a polar molecule, meaning that it has a region which has a slightly positive charge and another region with a slightly negative charge. Because of these dipoles, water is very good at attaching to other polar molecules, and because of its small molecules, it can worm its way between larger molecules.

Lipids are non-polar, so there is no way for water to attach to a lipid molecule. Instead, the non-polar lipids will bind to themselves, which is why oils and fats form droplets on the surface of water. This tendency to not mix with water is called hydrophobia.