This ExpeRimental episode from The Royal Institution is full of super explosive fun. Danielle and Michael show a group of kids how to make fizzy bottle rockets with some small, sports-capped plastic bottles, some Alka-Seltzer or fizzy vitamin C tablets, mugs or jars, warm water, and an outdoor space where you can really let the rockets fly. From rigb.org:
By putting fizzy headache/vitamin tablets into a bottle with a sports cap, they make incredible bottle missiles. As gas builds up inside the bottle, pressure increases until the lid pops. When this happens, the lid pushes against the ground, pushing the bottle upwards. The liquid firing out of the bottle pushes it further, just like the gases coming out of a real rocket…
Be aware of flying bottles, and read the lesson sheet (pdf), which includes this key safety note: “The fizzy headache tablets contain medicine which should not be consumed by children. Seek medical advice if you child accidentally eats a tablet or drinks the liquid from the rockets.”
What happens when you mix the tablets in really hot or really cold water? What if you use more than one tablet? Does the shape or size of the bottle matter?Related watching: Liquid Nitrogen and 1500 Ping Pong Balls and The Chemistry of Rockets – How do rockets work?