Seashells In Vinegar: Ocean Chemistry Experiment

Can you dissolve a seashell?
What happens when you put a seashell in vinegar?
How is that similar to ocean acidification?
Is acidification eating the shells?

This simple ocean science experiment shows how seashells dissolve in vinegar. It’s a good opportunity to explain to children why it’s important to protect our oceans from acidification. The project is easy to implement, but requires being checked on periodically, which also helps children to build up patience and to understand that climate change happens over time.

To start, all you need is:

  • 2 or more clear glass jars

  • Several seashells

  • White vinegar

  • Sea water (1 and a half teaspoons of salt per 1 cup of water)

It’s best to have multiple jars and different types of shells to investigate so that you can see if the type of shell affects how quickly the shell dissolves.

Let’s get started!

Step 1: Set out the two jars and label them. One should have only seawater, which will be the control in this experiment, and the other should have vinegar.

Step 2: Add a seashell to each container.

Step 3: Pour seawater into the jar with that label and cover the shell completely.

Step 4: Pour vinegar over the other jar and cover each seashell completely.

The chemistry of the ocean

This seashell experiment shows the chemical reaction between the shell’s material and its reaction to the acid in the white vinegar.

Seashells are formed of calcium carbonate (which, by the way, is also what eggshells are made of) and they are the external skeletons of mollusks — a group of various species such as snails, scallops, oysters, clams, and mussels.

When the seashells are soaked in vinegar, you will notice some bubbling action happening in that jar. This is the visible result of the chemical reaction between the calcium carbonate (a base) and the vinegar (an acid). Together, they produce the gas called carbon dioxide. Over time, the shells will become more and more fragile and will start to break apart when touched.

Logically, the thinner shells will react quicker and can change overnight. For the thicker ones, it may take more than 2 or 3 days to notice the transformation. You can set up a reminder to observe your seashells and note the changes.

Ocean acidification

This experiment is a great opportunity to talk about the effects of ocean acidification with your child or students. It starts with understanding the carbon cycle, which we have easily explained here.

The most important takeaway from this experiment is that when the amount of carbon dioxide in the air rises, so does the acidity of the ocean! The ocean absorbs carbon dioxide from the atmosphere, and the more we keep burning fossil fuels, the pollution in the atmosphere continues to increase, which has a worrisome effect on our oceans.

When absorbed in seawater, carbon dioxide forms carbonic acid, which causes the ocean to lose carbonate ions—important molecules that keep the oceans in balance. This leads to the increase of acidity in seawater. Because of the acidification, there are fewer vital minerals, such as calcium, and the species dependent on it can no longer produce or keep their shells. Over time, ocean acidification harms the shells of our favorite mollusks, among other things.

Last but not least, we recommend that you watch this video at the end of your experiment.

We have to take care of our planet! Our oceans play an essential role in keeping the Earth’s carbon cycle and overall health in balance.