Always wear eye protection during science experiments. Never handle sharp objects, open flames, chemicals, or other dangerous objects without adult permission and supervision.
Calcium carbonate (CaCO3) is an ionic compound made of a calcium cation and an anion consisting of one carbon atom and three oxygen atoms. CaCO3 is basic and reacts with acids to form water, a salt, and carbon dioxide. Because of its antacid properties, CaCO3 is the main ingredient in most stomach medicines.
In this simple demonstration, we're going to prove that seashells are made of CaCO3 by dissolving them in vinegar. The bubbles of CO2 that form during the chemical reaction are just the evidence we need.
Carefully place the seashell in the bottom of the container. You'll want to use a container that is at least twice the height of the shell.
Pour enough of the distilled vinegar into the container to cover the shell. You should soon start seeing bubbles of carbon dioxide forming.
Periodically observe your shell. How fast does it seem to be dissolving in the beginning? A day later? If the rate seems to be changing, why do you think this is?