Witness osmosis in action by dissolving the shell of an egg with vinegar.
Eggshells from chicken eggs, seashells, snail shells, and pearls are all primarily made up of the compound Calcium Carbonate (CaCO2). If this compound sounds familiar, that's probably because it is! CaCO2 is the main ingredient in many stomach medicines. It's also even included in many household cleaners.
Unlike in the seashell demonstration, a chicken egg won't just completely dissolve in vinegar. Chicken eggs are a bit more complex (for obvious reasons). Instead, we're going to see how, after dissolving the outer eggshell, certain components of the egg are left behind. Let's check it out!
Always remember to wear eye protection during science experiments. Never handle sharp objects, open flames, chemicals, or other dangerous objects without adult permission and supervision.
Place the raw egg at the bottom of the drinking glass. Be extra gentle so that you don't accidentally crack the eggshell.
Pour enough of the distilled vinegar over the egg, just so that it's completely covered. Almost immediately you should see small bubbles of carbon dioxide forming all over the shell.
Now, the hard part... be patient! The shell may take up two whole days to completely dissolve. After about a day, the brown shell on our egg had turned into a slime. We rinsed the egg with some water and added fresh vinegar to continue the reaction.
After the shell has completely dissolved, empty the vinegar from the glass and rinse the egg lightly with some water. Feel free at this point to remove your squishy egg from the glass in order to touch and observe it. Be extra careful, however, because the membrane that remains is fragile.
Now that we've taken a closer look at our squishy egg, we're going to go one step further and see how we can use it to observe a process known as osmosis, the movement of a fluid through a membrane. Return your egg to the glass and once again cover the egg, this time with water instead of vinegar.
Leave your egg in the glass for about a day, checking on it every now and then to observe its size. After some time you should notice that the egg is gradually getting larger as the water in the glass passes through the egg's membrane.