Ocean in a Bottle: an Oil and Water Science Activity

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Ah, the ocean. Sitting on the beach and watching the waves is so relaxing. Then you take a dive into the blue water and all your worries fade away. Since we can’t always be close to the ocean, why not bring the calming effect of the ocean to us?

Ocean in a Bottle Horizontal

In this oil and water science activity, you are going to learn how to make an ocean in a bottle (or jar if that’s what’s available at home). This way, you literally have the ocean at the palm of your hand anytime you want to look at it! 

How to Make Ocean in a Bottle

Materials:

Instructions:

  1. Fill the glass about ½ full of oil.
  2. Mix water with blue food coloring in a cup.
  3. Optional: use a dropper and slowly drop the blue water into the oil in the bottle. Observe how the water droplets stay together and do not mix with the oil.
  4. Pour the rest of the blue water into the bottle until the bottle is almost full.
  5. Replace the cap on the bottle. You may want to use hot glue or duct tape to secure it to ensure the cap won’t come loose. 
  6. Shake the bottle and watch the ocean appear in front of your eyes!
  7. Optional: if you wish, you can add glitter and mini ocean creature figures in the bottle. 
Ocean in a Bottle Bubbles Glitter

So pretty right? We added some sparkling crystal glitter to our ocean to make the blue water glisten. 

You may recognize the instructions above from a very similar experiment. In the DIY lava lamp activity, we also pour oil, water, and food coloring in the same bottle. However, we added Alka Seltzer tablets to make the colored water float up and sink down. 

Science Behind Ocean in a Bottle

Water and oil don’t mix. In scientific terms, they are immiscible. Why? Because they have different densities. 

Water is denser than oil – meaning, water molecules are closer together. That’s why when you drop the blue water into the oil, the water droplets sink down to the bottom.

Also, water is polar. This means that water molecules tend to stick to themselves because the positively charged hydrogen atoms attract negatively charged oxygen atoms. Oil molecules are non-polar and only mix well with other non-polar molecules. Therefore, when you mix oil and water, they form two separate layers.

Ocean in a Bottle Bubbles

Conclusion

This ocean in a bottle is a great sensory play for younger kids. They can shake the bottle all they want and the water and oil will eventually separate. If you have a toddler at home, you can make sensory bottles like this for calming effect.

When my kids get upset, I tell them to shake the bottle and don’t do anything until the blue water all sink to the bottom. It’s equivalent to us counting to 10 when we are angry – the ocean in a bottle calms them down.

You can also make the bottle ahead of time with mini ocean creatures in the ocean. Your kids will love discovering what ocean creatures are in the bottle and take them surfing by creating waves!

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