How does it work?

Ordinary foods can produce spectacular effects when mixed together. Have you ever seen what happens when you drop Mentos into cola? We now want to use a similar phenomenon—a chemical reaction—to make a rocket fly. When chemicals are combined, reactions can take place. This transforms the original ingredients into completely new substances.

In our experiment, the original substances are baking soda, citric acid, and water. When they come together, they create a gas called carbon dioxide (CO2). Because the gas needs space, high pressure builds up in the bottle. When the pressure gets too high, the CO2 pushes the bottle cap away and the gas flows out. The rocket is pushed upward into the air with the same force. This is called recoil.

• Try to find the perfect mixture of baking soda, citric acid, and water so that your rocket flies the highest.

• Do you know of any other reactions or processes that generate pressure? How could they be used as rocket fuel?