Ocean in a bottle activity : Fizzics Education

# Ocean in a bottle activity

### You will need:

• Vegetable oil
• Water
• A clear bottle with a screw-top lid
• Blue food colouring
• A funnel
• Paper towels for any spills

1

Fill the bottle halfway with water. Add some blue food colouring into the water.

NB: Notice how the food colouring drops through the water? This is because food colouring is denser than water. Density drives ocean currents around the world, here’s another science activity that explores this further.

2

Insert a funnel into the bottle and place this into the tray to catch any spillage. Carefully add the vegetable oil into the bottle so that it fills the bottle up to the very top without spilling.

3

Screw the lid tightly onto the bottle. Seal the bottle with tape… you don’t want any oil spills!

4

Tip the bottle from side to side and you get simulated ocean waves!

5

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### What's going on?

The ocean in a bottle activity is a classic demonstration that takes advantage of density as well as mixtures. Firstly oil is less dense than water, which means that each drop of oil is lighter than a drop of water (less mass per volume). This causes the oil to float above the water as it is more buoyant.

Secondly, oil doesn’t mix with water. This is because water molecules are far more attracted to other water molecules than they are to oil. Why? It’s got to do with electrical charges.

• A water molecule is polar, which means that one side of the molecule has negative charges and the other side has positive charges. These charges cause water molecules to be attracted together, where a negatively charged oxygen atom on one water molecule is attracted to a positively charged hydrogen atoms of another water molecule.
• Oil molecules are non-polar, meaning that there is no difference in charge across the oil molecule. This makes the oil hydrophobic, literally meaning ‘water-fearing’. As oil molecules are non-polar they are repelled by the charges of the water molecules – which means the oil cannot mix in the water.

The water and oil waves you see in the bottle mimic the turbulence of waves in the ocean. Real ocean waves are created by the action of the wind. The greater the wind, the larger the waves!

### Variable testing ideas

• Does adding salt make a difference?
• What if you add detergent to the mix?
• If water is warm, does it flow differently?