Activity Time: Naked Egg, Part 1

This is by far one of my favorite experiments.  I love how you can take a raw egg and dissolve the shell and you are left with this really weird rubbery egg! Then, we can use that egg to do even more experiments. (Watch for that on Friday in part 2!)

Here is what you will need:

  • Clear jars or cups (a lid is nice if you have it)
  • Eggs (raw–not cooked)
  • White vinegar
  • Tape and marker (to label your jars)

Optional equipment:  

  • Use other liquids to see how the egg shells react.  I used water, orange juice, root beer, and coffee.
  • A scale to measure the weight differences as you go through this experiment
  • Downloadable chart to document your observations (or make your own).

NOTE: Do not eat the egg! It will not be edible after this experiment. After handling the raw eggs, be sure to wash your hands.

This experiment will take several days, which is why it is good to have a jar with a lid if you can.  

  1. Label your jar(s) with the name of the liquid and the date. The date will help you remember when you started your project.  I recommend doing more than one egg in case something goes wrong. 
  2. If you are measuring weight differences, make sure you do this now.
  3. Gently place the egg in the glass jar. You want to make sure the egg doesn’t crack. Make sure the jar is roomy enough for the egg to expand. Trust me, my first jars were too small.
  4. Add the vinegar.  Make sure to fully cover the egg.  It will float a little, that is okay.   
  5. Watch to see what happens. Here is a little sneak peek for you…

The Science Behind the Bubbles

Egg shells contain calcium.  Vinegar is made up of acetic acid diluted with water.  The acid in the vinegar reacts with the calcium in the shells causing a chemical reaction.  This reaction creates carbon dioxide. That carbon dioxide forms into the bubbles you see on the egg.  

  1. If you are doing more eggs and different liquids, prepare those now.  Make several eggs in vinegar to save for part 2 on Friday!
  2. Observation Time. 
    • It will take 1-2 days for the vinegar to dissolve the shell.  
    • You should see a foamy layer on the top of the liquid in your jar.  
    • What happens during this time?  Did you notice any changes? Mark them in your chart!

Here are my jars all lined up.  The egg in the orange juice kept floating, so I weighed it down with some plastic chip clips in the jar. 

  1. After 1-2 days, carefully remove the eggs from the jars.  
    • If you are weighing the eggs, carefully dry them off and take the measurements.  Document your observations. 
    • If the shell is not fully dissolved, put the egg back in the jar with some fresh vinegar.  This happened to me; I think it was because my jars were a bit too small. 

Here is what my eggs looked like.  I had a couple of cracked shells. The eggs I put in the water, orange juice, soda, and coffee were all still intact, except for the cracks of course.   But look at that egg I put in the vinegar! Not only is the shell gone, but it is bigger than when I started. I weighed it, and it gained 30 grams. This egg started at 55 g, so it gained over half of its weight. 

Here is what my chart looked like when I was done.   (The chart linked above is a little different. I updated it after doing this experiment to make it better for you)

Why did the egg gain weight?

Here is an diagram of an egg that I found on www.exploratorium.edu

The weight gain in the egg is due to a process called osmosis.  The egg is surrounded by a thin semi-permeable membrane.  This is a fancy way of saying there are tiny holes in the membrane of the egg.  Water moves across this membrane from a liquid that contains more water in it (the vinegar) to the egg’s albumen, which has less water in it.  The movement of water stops when the level of water is the same on both sides of the membrane.  

Imagine sharing M&M’s with a friend.  Between you is a piece of paper with M&M size holes.   You have 10 M&M’s and your friend has 2. You move 4 M&M’s through the paper until  you each have 6. That’s what happens with the water.

We will explore osmosis more on Friday in Naked Egg Experiment Part 2.

Observe your egg.  Give it a little, gentle squeeze.

  • What does it look like?
  • How does it feel? 
  • Can you see the yolk inside?

Did anyone think it felt like a bouncy ball?  Did you try to bounce it? I did. This might get messy–it is best to do this part outside. 

As you can see, I dropped mine from a short distance.  It will break when you drop it from greater heights. Use a ruler or yardstick to test how high you can drop it before it breaks.  Were you surprised by what the egg did when it broke?

Don’t forget to come back for part 2 on Friday!

Cindy

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