Ocean Acidification Experiment

(Earth Science for ages 8+)


You have probably heard about climate change and how bad it is for our planet. It’s not always easy to see the long-lasting impacts, but in the video above, you can see how ocean acidification can impact critters that rely on their shells to live.

Below, you can find the instructions to do your own experiment testing the impacts of an acidic ocean on seashells. Here’s how it’s done:



White vinegar
Sparkling water
3 clear glass or plastic jars
Food scale
Adult supervision (Adult supervision at all times please)



  1. Start by mixing together some seawater. To one of your jars, add 1 cup of water and 1½ teaspoons of salt and stir until the salt is dissolved. Label this jar so you know it is the one with saltwater. It will serve as your control.
  2. To another jar, add 1 cup of white vinegar. Label the jar so you know this is the jar with vinegar.
  3. To your third jar, add 1 cup of sparkling water and be sure to label it.
  4. Using your pH strips, test the pH of the liquid in each jar and write down the results. If you are using homemade pH strips, record the color and be sure to mark whether it means the liquid is acidic, basic, or neutral.
  5. Next, weigh your seashells individually using your food scale. Write these numbers down and be sure you know which shell is which.
  6. Place one shell in each of your three jars, making sure you know which shell is which. Make a note of which shell goes in each jar.
  7. You may see tiny bubbles begin forming on the surface of the shells in some of the jars. Write down any observations you see and then set the jars in a safe place where they will be undisturbed. Leave them for 12-18 hours, checking back periodically and recording any new things you see.
  8. After 12-18 hours, write down your final observations, and then remove the seashells from the jars. Set them on paper towels or napkins to dry.
  9. Once the shells are dry, reweigh them with your food scale and write the new weights. What do you notice? Do the shells weigh the same that they did before they were soaked? Which shells lost the most weight?



The ocean acts as a huge carbon sink, which means it absorbs carbon in the atmosphere. As people burn fossil fuels and release carbon into the atmosphere, more and more of it is absorbed by the ocean.

Carbon then reacts with the seawater and produces carbonic acid, increasing the total acidity of the ocean. Mollusks, like snails, clams, oysters, and mussels, live within shells that are made of calcium carbonate, similar to eggshells.

When the acidity of the ocean rises, the calcium carbonate shells begin to deteriorate, which can kill the animals that depend on their shells to survive.

This experiment shows how shells react in liquids with different levels of acidity and demonstrates why it is important to protect the ocean and our planet from rising levels of carbon in the atmosphere.