The baking soda and vinegar will react to form carbon dioxide (a gas that has one carbon atom and two oxygen atoms), and the pressure created by the gas will force the lid off the container, launching your rocket into the air and crashing down.
Please, launch the rocket outdoors to prevent it from hitting someone or his/her property.This thing can shoot pretty high, so be very carefull! Happy making!
(As you can see It was icy outside when I made this. I made it in February.)
Or you don’t even need the body, you could just shoot the canister itself.