American Chemical Society: CO₂ to The Rescue Lab Activity

Invent a small device to rescue a cell phone from water.

This series of activities, developed by the American Chemical Society through grants from the National Science Foundation (NSF) and National Institutes of Health (NIH), is comprised of a lesson that begins with a design challenge: to invent a small device that could rescue a cell phone that accidentally falls into water. The teacher starts off by showing students a balloon that inflates with carbon dioxide gas as chemicals inside the balloon react with one another.

Students conduct a pair of chemical reactions to determine which of two acids react with baking soda to produce the most carbon dioxide gas. Once students determine the best acid to use, they compare the amount of gas produced with different amounts of baking soda. Finally, trying to use the smallest volumes possible, students discover how much of each reactant is needed to fully inflate a small zip-closing plastic bag to see if it can get a model clay cell phone to float.