Floating Egg

The floating egg experiment is a simple but fascinating way to learn about density and buoyancy. Using just an egg, water, and salt, you can make an egg sink or float. It’s a fun kitchen science activity that helps explain why some objects float in water while others sink, and how changing the density of a liquid can change the result.

What You Need

• 1 raw egg
• A clear glass or cup filled with plain water
• Salt
• A spoon for stirring

What to Do

1. Fill a clear glass with plain water.
2. Gently place the egg into the glass of plain water. Observe what happens—the egg sinks to the bottom.
3. Take the egg out and stir a few tablespoons of salt into the water. Keep adding and stirring until the salt dissolves completely.
4. Place the egg back into the salty water. This time, the egg floats!

What Happens

In plain water, the egg sinks straight to the bottom because it is denser than water. But when you add a lot of salt, the water becomes much denser. At a certain point, the density of the salt water becomes greater than the density of the egg. This makes the egg float on the surface instead of sinking.

The Science Concept

This experiment demonstrates the concepts of density and buoyancy:

• Density: Density is how much mass an object has compared to its volume. If an object is denser than the liquid it’s in, it will sink. If it’s less dense, it will float.
• Plain water: The density of water is not enough to hold up the egg, so the egg sinks.
• Salt water: Adding salt increases the mass of the water without adding much extra volume, which increases its density.
• Buoyancy: When the water is denser than the egg, the upward buoyant force is strong enough to lift the egg, making it float.

Real-Life Connection

This same principle explains why it’s easier to float in the ocean than in a swimming pool. Ocean water has dissolved salts, which makes it denser than fresh water. That’s why swimmers can float more easily in seawater. The Dead Sea, which has a very high salt concentration, is so dense that people can float almost effortlessly on its surface.

Fun Variations

• Gradual floating: Add salt a little at a time and test the egg after each addition. Notice the point when the egg starts to hover in the middle instead of sinking or floating.
• Different objects: Try small fruits (like grapes or cherries) to see if salt water can make them float too.
• Layered water: Carefully pour fresh water on top of salt water in the same glass. Can you make the egg float in the middle?
• Temperature test: Try warm salt water versus cold salt water. Does temperature affect how fast the egg floats?

Learning Outcome

The floating egg experiment teaches the relationship between density and buoyancy in a simple, visual way. It shows how adding substances like salt can change the density of water and affect whether objects sink or float. It also connects science to real-world experiences, like floating in the ocean, making the lesson both practical and memorable.