How does the bouncy egg science experiment work? The egg becomes bouncy as a result of a chemical reaction between the eggshell and the vinegar. The eggshell of a chicken egg is made of calcium carbonate, and vinegar is a weak acid. If you’ve ever mixed baking soda and vinegar together, you know the violent reaction that results. The calcium carbonate that makes up the eggshell will react with the vinegar the same way baking soda reacts with vinegar (just a lot less violently). You know the vinegar and calcium carbonate of the eggshell are reacting because of the small bubbles that form around the egg when it is placed in the vinegar. These small bubbles are carbon dioxide gas, which are the result of the reaction between calcium carbonate and vinegar. Once the shell of the egg is gone, all that is left covering the egg is a thin membrane. The vinegar begins working on the egg’s membrane. The membrane of a chicken egg is selectively permeable. The vinegar is able to cross the selectively permeable membrane of the egg through osmosis. The vinegar toughens up the membrane of the egg making it bouncy!