Disappearing Shell

Good morning scientists! Our initial results are in from our egg in vinegar disappearing shell investigation. We set it up last night before bed, and my little scientist was surprised to see how his egg changed overnight.

Materials

Disappearing Shell (2)

Plastic Container with Lid

Egg (Any variety, we used brown cage free large eggs)

Distilled White Vinegar

Investigation

**Thoroughly wash your hands with soap and water when finished with the lab, raw eggs can carry diseases. Also make sure to wash well each time you interact with your disappearing shell investigation.** 

  1. Place an egg into a plastic container. Completely cover the egg with white vinegar. Place lid on the container and let it sit over night. 

  2. In the morning or about 12 hours later, check on your egg to see the results. 

  3. After 12-24 hours (When the liquid looks like it has slimy outer coating of the egg floating throughout like the above picture) change out your white vinegar and let sit for one week. I gently washed my egg when I changed out the white vinegar. 

  4. Check on your egg after one week and the shell should be completely dissolved leaving just the cell membrane and contents. Disappearing Shell (29)

Extended Learning

  • After the shell completely dissolves try pouring out the white vinegar and replacing it with a different liquid like water or cornstarch.
  • Try the same investigation but first use a white crayon to draw a face on the egg shell or write a secret message.
  • Follow steps 1-3 (wait the full 24 hours) but instead of refilling your container with white vinegar hold your egg a short distance above the sink and let go. Keep changing the height to bounce your egg in the sink to see how high you can get.

Talking Points

Why did the egg shell disappear overnight? The answer is that the white vinegar is an acid (pH 2.4) and was able to slowly dissolve or eat away the hard outer shell of the egg. pH scale is the scale by which liquids are determined to be an acid, base, or neural. The pH scale ranges from 0-14. An acid is a chemical that has a pH less then 7 or neutral. Egg shells are made up of calcium carbonate. Calcium carbonate is a base (pH 9.91). A base is a chemical with a pH higher then seven or neural. When you mix an acid and a base together a chemical reaction occurs. A chemical reaction is a change or reaction between two substances that completely and permanently changes the original substance. As soon as you put the white vinegar in the container with the egg you should have noticed that small bubbles formed along the outside of the egg shell. This was the start of the chemical reaction and the tiny bubbles are carbon dioxide gas formed as a bi-product of your reaction. After the protective shell of the egg dissolves completely you are left with the cell membrane and the contents of the egg. Cell membrane is the thin outer layer of a cell, it is semipermeable (has tiny holes to allow movement of water, nutrients, and wastes into and out of the cell).

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