 Density is the amount of mass in a given volume, or amount of space. Mass is dependent on the number of molecules in an object. Objects that are more dense than water will sink and objects that are more dense will float! This time, we’ll experiment with density using an egg and see how it reacts in different solutions.

First we need to decide if an egg is more or less dense than water. Place the egg in a glass filled with water. Does the egg sink or float? After you see what happens, take the egg out of the glass and dump in a bunch of salt – a good ¼ of a cup will probably do the trick but you may need to add more. Mix the salt in the water. Some of the salt might not totally dissolve in the water and that’s okay. Now place the egg back in the glass, does the egg sink or float? If your egg is still sinking it means that you will need to add more salt to the solution.

What we’re seeing is that when the egg is in regular water it sinks to the bottom of the glass. This happens because an egg itself is denser than water. When you add salt to the solution, you are increasing the mass without changing the volume by very much. This creates a solution with a greater density. The egg will float in the salt water solution because it is less dense!

 Do you think you could change the density of water in a different way?

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Standards for Do Eggs Always Float?

Next Generation Science Standards