Float or Sink? The Saltwater Egg Experiment


In our exciting audio adventure, Under Drake’s Flag, we spend lots of time aboard Sir Francis Drake’s ships at sea. Seawater has some amazing and unique scientific properties. How much do you know about one key property of saltwater? Try this fun and easy experiment to learn more.

Have you ever been swimming in the sea? Did you notice that it was easier to float in the ocean than it is to float in a swimming pool? This neat experiment that will help you understand why materials float better in salt water than in fresh water.

Step 1: Gather Your Materials.

 You’ll need:

  • Two raw eggs
  • Tap water
  • A tablespoon for measuring and stirring
  • Cups or containers (deep and wide enough to float/sink an egg)
  • Table salt

Step 2: Conduct the Experiment.

  1. Fill two cups or containers at least half full with tap water.
  1. In one of the containers, add a tablespoon of salt. Stir well until salt completely dissolves in the water. Repeat this step a few times until the water is saturated with salt. The more water in your cup/container, the more salt you will need to add.
  1. Place one raw egg in each of the containers.

Step 3: Observe!

What happens to the two eggs? Observe the two containers and record your results.

Step 4: Learn the science behind this amazing trick…

The explanation behind this neat trick is actually very simple. It’s all because of DENSITY!

In this experiment, you observed that the egg placed in saltwater floated while the one in tap water didn’t. This is because saltwater is denser than fresh water, so the egg does not sink.

Density is the amount of matter that is contained in a given space or volume. When there is more matter in a given space, the object is considered to be denser, or heavier. (But be careful – you can’t use the words density and weight interchangeably.)

In the control cup (no salt) – the egg is denser than the tap water, so it pushes away the water particles to make space for itself. And that’s why the egg sinks

But in the case of the saltwater cup, the water is heavier than ordinary tap water because it is saturated with salt particles. It is more capable of holding the egg up, and the egg floats.

So next time you go to the beach or swim in the ocean, you’ll know why it is easier to float than at the community swimming pool. Science is pretty cool, isn’t it?

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