The shell of chicken egg is typically primarily made up of calcium carbonate. If you soak this egg shell in vinegar (which is normally around 4% acetic acid), you start a chemical reaction that dissolves the calcium carbonate shell. The acetic acid reacts with the calcium carbonate in the egg shell and releases carbon dioxide gas that you see as bubbles on the shell. So how does the egg stay together? The egg insides remains intact because its held together by the two fragile membranes just inside the shell.
So let's get started! Here's what you'll need:
- Vinegar (at least 16 ounces)
- A couple of glasses
- Raw eggs
Thankfully, the process is easy. So that you don't break the egg from the get go, carefully place the egg into the glass and then fill the glass with vinegar so that the egg is completely covered. If the egg starts floating a bit, that's okay! As long as there's enough vinegar in the glass to mostly cover the top of the egg, you're golden.
Next is the worst part of the experiment: waiting. You must wait for the acetic acid in the vinegar to react with the calcium in the egg shell. Shortly after you cover the egg, you should see some bubble appearing on the outside of the egg. What you're looking at is carbon dioxide gas produced from the reaction. It can take anywhere from 12-24 hours for a good portion of the shell to be removed. Good progress is being made when you notice a white frothy scummy layer on the surface of the vinegar.
Once you've let the egg soak for a day, you can finally take it out! You have to be careful when you're taking the egg out of the glass. While fishing it out with a spoon might sound like a good idea, it can result in the egg breaking or being damaged. Instead, pour the liquid into another cup and gently catch the egg with your hand as it comes out. One you have the egg, you should be able to literally rub the shell off of the egg with you fingers. The shell will come off as a white powdery substance. Be careful during this process so that you don't break the egg.
If your egg isn't quite fully naked yet, fill up another glass with vinegar and soak the egg overnight again. After two days of soaking, you should have a completely naked - and very, very cool looking - egg. Notice that after the second day of soaking your eff is a bit bigger than it was after the first day. This is because some of the vinegar (and some of the water in the vinegar) has moved through the egg's semi-permeable membranes to the inside of the egg. Ladies and gentlemen, this is called osmosis!
For a list of fun things to do with your naked egg, instructions on how to shrink your egg, information on eating the egg or how it smells and some science fair project ideas, click here.