One of our favorite family vacation destinations is the beach. I just love it! The sand, the waves, and the sun are all glorious. I just can’t get enough!
When we do take a trip to the beach, we usually spend as much time in the sand and water as possible. We dig in the sand, snorkel in the shallow water when the waves are calm, jump the waves when they are high, and nap under our beach canopy when needed.
One of our favorite things to do as a family on the beach is collect shells. We find them on early morning walks on the beach and as they wash up throughout the day. By the end of our vacation, we usually have a sand bucket full of them.
When we get home, we sort them according to their types. We sometimes use a shell guide to try and identify them. We might also put them in jars to admire them and remember our trip. We can also use them for a chemistry experiment!
What Is A Seashell?
Who isn’t mesmerized by shells being washed up on shore by the crashing waves? Their shapes and colors make them like treasures pulled from the deep mystery of the ocean. Collecting shells on the beach can be addicting. You never know what the next shell might look like.
But what are seashells?
Seashells are exoskeletons formed by soft-bodied mollusks such as oysters and clams for protection from the environment and predators. These mollusks secrete a material made mostly of calcium carbonate which builds up and hardens to create the shell. As the animal grows, more shell is created.
Some people think of the shell as the home of the mollusk. This is kind of true. The animal does live in its shell. However, the shell is actually attached to the animal’s body, so the animal cannot leave the shell unless it dies. These are the empty shells we find on the beach.
Seashells And Chemistry
When we want to know the chemical composition of something, we test it. Doing various simple chemistry experiments and tests can positively identify some substances and rule out others. An easy test for the presence of calcium carbonate uses vinegar.
Place a shell in a glass and add enough vinegar to cover the shell. Observe.
See the bubbles accumulating on the surface of the shell. These are carbon dioxide bubbles created by the chemical reaction between calcium carbonate, a base, and acetic acid in the vinegar, an acid. The shell is breaking down in this process. If you leave the shell in the vinegar for a few days, the vinegar will visibly breakdown the shell. Whatever is left of the shell would be thin and brittle.
Geologists use this type of test to determine the presence of limestone in rock. Limestone contains calcium and will react to an acid in the same way.
Try this easy experiment at home to see how the calcium in seashells react to acid or test rocks with acid to determine if they contain limestone.
top and botttom images courtesy of depositphotos