Simulations & Videos for

Lesson 3.5: Density: Sink and Float for Liquids


  • Oil is more dense than alcohol, but less dense than water. The molecules that make up the oil are larger than those that that make up water, so they cannot pack as tightly together as the water molecules can. They take up more space per unit area and are less dense.


  • Water molecules are packed more closely together than the long molecules that make up oil.
  • The oxygen atoms in water are also smaller and heavier than the carbon atoms in oil. This contributes to making water more dense than oil.


  • Even though the molecules that make up alcohol contain a heavier oxygen atom, alcohol is less dense than oil because alcohol molecules do not pack closely together.