Floating bubbles

My sister showed me an interesting experiment that was displayed in her science fair today.  In a glass jar, bicarbonate and vinegar are mixed, creating a chemical reaction in which carbon dioxide is released. Soap bubbles are then released into the jar.  These bubbles will float in the jar, because the bubbles have air inside of them, while they are surrounded by carbon dioxide. Carbon dioxide is more dense than air, which is what makes the bubbles float.