Superhero Science: EXPLOSIONS!
Superhero Science with Film Canister Rockets
Every good superhero action sequence comes with an explosion scene. Get in (safely) on the piece of the action! Warning: It’s impossible to do this activity just once. It is addicting and habit-forming. Proceed at your own risk!
- Film canister with a snap-on lid
- Alka-Seltzer tablets
- Safety Goggles
- Put on your safety glasses
- Divide an Alka-Seltzer tablet into pieces
- Fill the film canister about half full with water.
- Place one of the pieces of Alka-Seltzer tablet in the film canister
- Experiment with different amounts of water and Alka-Seltzer… how long does it take to go off?
How Does It Work? (explanation from Steve Spangler Science)
The first part of this experiment is just a variation of the classic Alka-Seltzer film canister rocket. The same principle is at work here. In both cases, carbon dioxide gas builds up so much pressure the lid is forcibly launched. With an Alka-Seltzer tablet, the CO2 is produced as a result of a chemical reaction. With the soda, the CO2 is produced as a result of vigorous shaking. This provides a good contrast between a physical and chemical change.
The fizzing you see when you drop an Alka-Seltzer tablet in water is the same sort of fizzing that you see when you mix baking soda and vinegar. The acid mixes with the sodium bicarbonate (baking soda) to produce bubbles of carbon dioxide gas. If you look at the ingredients of Alka-Seltzer, you will find that it contains citric acid and sodium bicarbonate (baking soda). When you drop the tablet in water, the acid and the baking soda react to produce carbon dioxide gas. The gas keeps building up until finally the top pops off. The lid of the canister is the path of least resistance for the gas pressure building up inside, so it pops off instead of the stronger sides or bottom of the canister bursting open.
We can thank Sir Isaac Newton for what happens next. When the build up of carbon dioxide gas is too great and the lid pops off, Newton’s Third Law explains why the film canister flies across the room: for every action there is an equal and opposite reaction. The lid goes one way and the film canister shoots out of the tube in the opposite direction.
We liked this experiment SO much we went through an entire box of Alka-seltzer (and a good portion of the afternoon)!!! :)