Floating Egg

Author: Maddie Van Beek

Have you ever heard that muscle weighs more than fat? The truth is, a pound of muscle weighs the same as a pound of fat! It’s just that muscle is denser than fat. Check out the photo below:

http://cdn2-b.examiner.com/sites/default/files/styles/image_content_width/hash/4d/e6/4de678acd329b0766b9f2b067d49fec6.jpg?itok=x7A5pn0j

As you can see, one pound of muscle simply takes up less space than one pound of fat. This is because the material in muscle is more dense than the material in fat. 



How much do you know about density? If you’ve been following us for a while, you may have tried our liquid stacking tower experiment that demonstrates the densities of different liquids. Check that out here (http://discoveryexpress.weebly.com/homeblog/rainbow-in-a-jar-learning-about-liquid-density)! Today, we are going to create an easy demonstration involving liquid density just by using an egg and salt water. 



What IS density?

http://astro.unl.edu/classaction/outlines/intro/density.jpg

Even though two different items might take up the same amount of space, their densities may be different. Take a look at the photo below. All of the cubes are the same size, yet some of them weigh more than others. Why is that? Because their densities vary. For example, wood is less dense than steel. 

http://www.flinnsci.com/store/catalogPhotos/AP6058cat.jpg

http://inspirationlaboratories.com/wp-content/uploads/2012/11/density-comparison.jpg

As you can see, the object on the left side has greater density than the object on the right side. Although both cubes are the same size, the matter in the left cube is packed more tightly, and thus is more dense than the cube on the right. 



Here is yet another example of the varying densities of different materials. 

http://www.mathswrap.co.uk/wp-content/uploads/2013/03/Density-cubes.jpg

Make sense? 



Now that you understand the basics of density, here is a video that explains how to find density:

Let’s try our density demonstration! 



YOU WILL NEED:

• Water
• Salt
• An egg
• A glass
• Teaspoon

Here’s what to do!

1. First, fill a glass with one cup of plain water. 
2. Carefully drop the egg into the glass of tap water. What happens? Make a sketch of the egg in your observation journal and record any other observations. 
3. You should have seen the egg sink to the bottom of the glass of tap water. What do you think will happen if you drop an egg in a glass of salt water? Let’s find out!
4. Remove the egg from the glass, and then use a teaspoon to stir salt into your glass of water. Make sure the salt dissolves completely before you add more. Count how many teaspoons of salt it takes before no more salt will dissolve. When you reach the point where salt will no longer dissolve, your water is saturated. You cannot dissolve an unlimited amount of salt (or any solute).  Liquids (a solvent) reach a certain point where they will no longer dissolve any more solute (in this case, salt). 
5. Now that you have your salt water solution, carefully pour half a cup of tap water on top of the salt water. Make sure you do this so that you disturb the salt water as little as possible. What do you think is more dense, the salt water or the tap water? Why? 
6. Carefully drop the egg into the glass of water. What do you see? How was this different than the first time you dropped the egg into the tap water? 
7. You should have seen the egg sink past the tap water in the top half of the glass until it hit the salt water. It “magically” floats in the middle of the glass. Why does it do this? As you know, the salt water is more dense than the tap water, so the egg sinks right past the tap water but floats on the surface of the salt water. 
8. Extension: How else can you determine which liquids are more dense? Use a balance to compare different liquids. Make sure you use two identical cups with equal amounts of liquids when you are making comparisons. 
9. Look at the example below: You can see that water weighs more than an equal amount of rubbing alcohol. This means that the rubbing alcohol is less dense than water. 

http://www.middleschoolchemistry.com/img/content/lessons/3.5/alcohol_vs_water.jpg

10. Find other household liquids that you can compare! Make sure to record your observations in your observation journal.



Since you have eggs already, check out these other “eggcellent” activities! 

Acid Base Reactions: http://discoveryexpress.weebly.com/homeblog/experimenting-with-eggs-acid-base-reactions-and-osmosis

Nature Abhors a Vacuum: http://discoveryexpress.weebly.com/homeblog/nature-abhors-a-vacuum-how-to-put-an-egg-in-a-bottle

Sedimentation and Crystallization: http://discoveryexpress.weebly.com/homeblog/sedimentation-and-crystallization-how-to-make-egg-geodes




References:

• https://www.youtube.com/watch?v=kE8I_M2pyg8
• http://www.middleschoolchemistry.com/lessonplans/chapter3/lesson5
• http://www.sciencekids.co.nz/experiments/floatingeggs.html