Chemistry

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Video

Materials

• Baking powder
• Water
• 1 film canister (or similar canister with a lid)

Explanation

Baking powder consists of about 30 % baking soda, 40 % some acid (for example cream of tartar) and 30 % some moisture absorbing substance (for example corn starch). When baking powder and water are mixed, the baking powder begins to react with itself - bicarbonate and the baking powder's own acid reacts and forms a salt (which one depends on the acid) as well as carbon dioxide.

The carbon dioxide is in a gaseous state, which means that it takes up a lot of space. The more carbon dioxide that is formed, the more the pressure inside the film canister increases. This high pressure is due to the carbon dioxide molecules being compressed into a small volume at the same time as they collide a lot with each other and the walls of the film canister. When the pressure becomes high enough, the carbon dioxide molecules shoot out of the film canister, at the same time as the lid flies off and the film canister lifts off.

Experiment

You can turn this demonstration into an experiment. This will make it a better science project. To do that, try answering one of the following questions. The answer to the question will be your hypothesis. Then test the hypothesis by doing the experiment.

• What happens if you use hot water?
• What happens if you use more water?
• What happens if you use more baking powder?
• What happens if you use a larger canister with a lid, as well as more water and more baking powder?

Variations

A launch pad can be made by taping an empty toilet paper roll onto a stiff piece of paper, and then placing the film canister inside the toilet roll.

You can also mix baking powder and water in a closed plastic bag and see how the bag expands (and possibly bursts).

Instead of baking soda, you can use some type of effervescent tablet, such as an Alka-Seltzer or a vitamin C tablet. These also usually contain bicarbonate and some acid.

You can also mix baking soda and vinegar instead.

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