Naked Eggs – A Different Twist
It’s a classic experiment and a sure-hit favorite around Easter. Soak a raw egg in vinegar and over the course of time, the vinegar will dissolve the eggshell. What you’re left with is the egg’s translucent membrane to protect the egg. Even though it’s a classic, I’ve never done this demo on the television show because it takes so long for the eggshell to dissolve in vinegar (about 7 days). But this year I had to try something new. What about substituting 3 molar hydrochloric acid for vinegar? The goal is to dissolve the calcium carbonate in the egg shell and 3M HCl should do the trick. The first attempt was a success, but I stumbled upon a great technique at the same time. Instead of doing the reaction in a beaker, I put the egg in a 1000 mL graduated flask and cover the egg with 150 mL of 3M HCl. This makes the reaction easy to see and very controllable. As the acid dissolves the egg, carbon dioxide gas is produced and a white foam of calcium chloride slowly rises in the cylinder. When the reaction is complete (you’ll see the naked egg), rinse the egg and… Voila… you got a naked egg! Watch the video.
Before you flood the post with comments, I know that hydrochloric acid is not in the kitchen chemist’s bag of goodies. But you have to share something for the chemistry teachers every once in a while.