The egg shell in vinegar experiment demonstrates how calcium carbonate reacts with acetic acid. About 95 percent of an eggshell is made up of calcium carbonate. Other materials mostly made from calcium carbonate include seashells and limestone. The remaining 5 percent of the eggshell is made up of calcium phosphate, magnesium carbonate, and proteins.
About 3 percent of vinegar is acetic acid.
When you put an egg into a glass of vinegar, bubbles of carbon dioxide immediately begin to form around the entire egg. The egg shell dissolves within 24 hours, leaving behind a squishy bouncy translucent egg.
According to the Department of Physics at the University of Illinois at Urbana-Champaign, the chemical reaction behind this is such: CaCO3+ 2H+ -> Ca+2 + H2O +CO2