Carbon dioxide is a colorless, odorless gas that's part of our atmosphere.
It's found in a variety of products and it's a by-product of a lot of chemical reactions. For example, in baking bread, yeast and sugar in the dough react creating energy and carbon dioxide. The carbon dioxide gas is what causes the dough to rise or puff up. When you open a can of soda, the whoosh sound you hear and the fizz is carbon dioxide escaping. Try this experiment to discover more about the chemical reactions of carbon dioxide.