The film canisters are usually old 35mm types which are getting harder to get hold of nowadays. Photography shops may have used ones they may give you for free or at least know where you could get some.
Students can experiment with various types of propellant. Vinegar and baking powder is the most common, although Alka Seltzer and water or chalk powder and vinegar may be asked for. The reactions will vary in strength so this practical may need to be conducted outdoors.
Equipment required (per set):
The decoration of the rocket may make a difference to the trajectory and height the rocket will attain, mainly due to the weight of the finished rocket. Students may want to experiment with fins, nose cones etc.
Some canister lids pop off more easily than others, try to get canisters as similar as possible in order to be fair.
The rockets are powered by compressed gas, namely CO2 which is formed when the baking powder comes into contact with the vinegar (ethanoic acid). Alka Seltzer and similar tablets contain baking powder and dehydrated citric acid, When water is added, the citric acid mixes with the baking powder to produce CO2.
The gas created exerts great pressure on the canister until the lid pops off.
The contents of this page are for information only. Please refer to CLEAPSS or ASE safety advice and/or publications before undertaking any preparation, practical experiment or using any equipment featured on this site or any other.