Film Canister Rockets:
You’ll need:
• One empty 35mm plastic film canister and lid. These are getting harder to find, but stores that develop film should have some. They are also available on line. (The white canisters work much better than the black ones do)
• Water • Safety goggles
- Put on those safety goggles and head outside - no really, when this works, that film canister really flies! If you want to try the indoor version, do not turn the canister upside down in step 5.
- Break the antacid tablet in half.
- Remove the lid from the film canister and put a teaspoon (5 ml) of water into the canister. *Do the next 2 steps quickly
- Drop the tablet half into the canister and snap the cap onto the canister (make sure that it snaps on tightly.)
- Quickly put the canister on the ground CAP SIDE DOWN and STEP BACK at least 2 meters.
- About 10 seconds later, you will hear a POP! and the film canister will launch into the air!
Caution: If it does not launch, wait at least 30 second before examining the canister. Usually the cap is not on tight enough and the build up of gas leaked out.
How does it work?When you add the water it starts to dissolve the alka-seltzer tablet. This creates a gas call carbon dioxide. As the carbon dioxide is being released, it creates pressure inside the film canister. The more gas that is made, the more pressure builds up until the cap it blasted down and the rocket is blasted up. This system of thrust is how a real rocket works whether it is in outer space or here in the earth's atmosphere. Of course, real rockets use rocket fuel. You can experiment controlling the rocket's path by adding fins and a nose cone that you can make out of paper. Be safe and have fun!
DIY Lava Lamps: You’ll need:
• A clean 1 liter clear soda bottle
• ¾ cup of water • Vegetable Oil • Fizzing tablets (such as Alka-Seltzer) • Food coloring
- Pour the water into the bottle.
- Use a measuring cup or funnel to slowly pour the vegetable oil into the bottle until it's almost full. You may have to wait a few minutes for the oil and water separate.
- Add 10 drops of food coloring to the bottle (we like red, but any color will look great.) The drops will pass through the oil and then mix with the water below.
- Break a seltzer tablet in half and drop the half tablet into the bottle. Watch it sink to the bottom and let the blobby greatness begin!
- To keep the effect going, just add another tablet piece. For a true lava lamp effect, shine a flashlight through the bottom of the bottle.
How does it work?
To begin, the oil stays above the water because the oil is lighter than the water or, more specifically, less dense than water. The oil and water do not mix because of something called "intermolecular polarity." That term is fun to bring up in dinner conversation. Molecular polarity basically means that water molecules are attracted to other water molecules. They get along fine, and can loosely bond together (drops.) This is similar to magnets that are attracted to each other. Oil molecules are attracted to other oil molecules, they get along fine as well. But the structures of the two molecules do not allow them to bond together. Of course, there’s a lot more fancy scientific language to describe density and molecular polarity, but maybe now you’ll at least look at that vinaigrette salad dressing in a whole new way.
When you added the tablet piece, it sank to the bottom and started dissolving and creating a gas. As the gas bubbles rose, they took some of the colored water with them. When the blob of water reached the top, the gas escaped and down went the water. Cool, huh? By the way, you can store your “Blobs In A Bottle" with the cap on, and then anytime you want to bring it back to life, just add another tablet piece.
Go to ScienceBob.com for more at-home experiment ideas.
