In this activity, we will build a rocket from common household items.
Warning: This activity involves a flying projectile. Make sure you have an adult with you and wear eye protection. Do this activity outside or in a high-ceilinged building like a hall. Never launch with anything breakable above the rocket, especially your face. NEVER point your canister rocket at ANYTHING, except the sky!
You will need
A white film canister
Baking soda (sodium bicarbonate)
Vinegar (any colour will work, but white is easiest to clean up)
A Paddle Pop stick or teaspoon
A plate, saucer, tray or similar
Glasses, sunnies or safety goggles
An adult
What to do
Take the lid off the film canister. Before adding the ingredients, practice putting the lid and placing upside down as described in step 4.
Put on your eye protection.
Pour a small amount of vinegar, about 5ml deep, into the body of the canister.
Using the teaspoon or Paddle Pop stick, place enough baking soda to fill the recess in the lid.
Hold the body of the canister in one hand and the lid in the other. Quickly and firmly press the lid completely on, place the canister lid down on the plate and stand back. Make sure your plate is on a level surface.
Your canister rocket will blast off seconds later. The exact timing will depend on the canister, temperature, amount of ingredients and how much you packed the baking soda in.
Have close look at the lid and bubbling ingredients left on the plate
What's happening?
When vinegar and baking soda mix together, there is a fast chemical reaction. There are several products of the reaction, although it is the carbon dioxide gas (C02) that pops the lid off. We'll have a look at the whole reaction later. As more and more carbon dioxide is produced, the bits of carbon dioxide (called molecules) are squashed together and begin to push, or apply a force, on all the inside surfaces of the canister, including the lid.
Pressure is defined as a force over an area. In this case, it's the force of the carbon dioxide pushing over the inside area of the canister. As the carbon dioxide builds up, so does the pressure inside the canister. The pressure quickly pops the lid off.
A good way to understand what is happening is to take a deep breath in, seal your lips and slowly breathe back out into your mouth. Eventually your mouth cannot hold the pressure and your lips will unseal, letting some air out. Caution: don't overdo this as you can hurt your eardrums.
The carbon dioxide gas pushes down on the lid, although as it is sitting on the plate, it cannot go anywhere when it pops. The carbon dioxide is also pushing on the inside base of the canister (the top of your rocket) and this pushes it into the air.
But enough physics, let's have a look at the chemical reaction.
As vinegar (dilute acetic acid) is a weak acid and baking soda (sodium bicarbonate) is a weak base, it is an example of an acid-base reaction. The equation is shown below:
HC2H3O2 + NaHCO3 -- > NaC2H3O2 + H2CO3 Acetic acid plus sodium bicarbonate makes sodium acetate plus carbonic acid
The H2CO3 (carbonic acid) then breaks down into water and carbon dioxide:
H2CO3 -- > H2O + CO2
Carbonic acid makes water and carbon dioxide
As the carbon dioxide is a gas, the mess you have to clean up will be a mixture of water and sodium acetate. You may also have some vinegar or baking soda left over, depending on the exact amounts you used.
