It is a rocket powered by a chemical reaction.
Baking soda and vinegar react to make gas, which is trapped in the corked bottle. When the gas pressure is great enough to push the cork out, the rocket flies up in the air.
Pour 200ml vinegar into the bottle (if 1L; use half cup vinegar for a 710ml bottle).
Add a couple of teaspoons of baking soda to the tissue, and roll it up like a burrito, so the baking soda does not fall out and the package is narrow enough to fit through the mouth of the bottle.
Students can do these steps.
Make sure that you are away from the students, or with only a pair of students invited to come with their materials to the launch pad.
Students watch while the adult pushes the baking soda package into the bottle, corks the bottle, shakes the bottle once, then stands it up for take off.
Run away from the launch pad to a safe distance (30-50m). Even if it takes a little time, the tissue will disintegrate to mix the baking soda into the vinegar, the gas released will build up enough pressure to push the cork out, and shoot the rocket high into the air.
If you think gas is escaping more slowly (around the side of the cork, for example) and the rocket will not fly, kick it over with your foot before reaching down to take it apart (so the rocket does not go off in your face), and reset it.
A rocket nicely demonstrates Newton's 3rd Law - for every action there is an equal and opposite reaction. The gas and liquid shooting downwards out of the bottle (the 'action') pushes on the bottle ('reaction') sending it upwards.
For a dramatic demonstration of Newton's 2nd Law, set the bottle right-side-up for take off (with the cork pointing upwards), making sure there is a mound of gravel or something around the base of the bottle so that it will not tip over. With the same amount of baking soda and vinegar, the cork flies way higher than the bottle (be careful with set up - the cork shoots out of the bottle really fast). With the same force, the smaller mass of the cork accelerates more than the larger mass of the bottle.
With older students, model the chemical reaction that powers the rocket:
Give each student a model of HCO3 (baking soda) and H (the atom that makes vinegar acidic). We started with these in the rocket.
The baking soda and vinegar molecules react and rearrange to make two new molecules. Ask students to figure out what these molecules are, giving them the hint that one of them is water.
The products of the reaction are water (H2O) and carbon dioxide (CO2).
Carbon dioxide is a gas, and as more and more of it is made by the chemical reaction, the gas builds up in pressure until it blows the cork out of the bottle.
Once the cork is released, the gas can escape by shooting out of the bottom of the rocket. This force propels the rocket upwards.
A rocket that goes to space acts on the same principal of action and reaction: the exhaust is expelled out of the back of the rocket, and this force is countered by a force on the rocket that propels it upwards.
Purchase molecule models online at Indigo Instruments https://www.indigoinstruments.com
