Alka Seltzer Blast-off 2

This project effectively demonstrates the Newton's Laws of Motion.

First Newton's Law of Motion states that an object either remains at rest or continues to move at a constant velocity unless a force acts on it.

• The rocket is at rest, but when it's acted upon by the chemical reactions of water and the Alka-Seltzer tablets, it has a powerful lift-off. The force of the reaction blows off the film canister lid.

Second Newton's Law of Motion states that Force is equal to mass multiplied by acceleration.

• Force = mass x acceleration
• The force of that lift-off is equal to the mass of the film canister, the water, and the tablet inside multiplied by the acceleration provided by the chemical reaction.

Third Newton's Law of Motion states for every action, there is an equal and opposite re-action.

• As the film canister lifts off, the canister lid, water, gas, and slide experience the downward force of the push. The lid pops off. The water and the gas spread out, but because the slide is secured on the ground, we can't see it move.

The Chemistry behind the project:

1. Alka-Seltzer tablets contain sodium bicarbonate and citric acid.
2. When the Alka-Seltzer tablet piece comes in contact with the water inside the film canister, it begins to dissolve. 
3. This results in sodium citrate, water, and carbon dioxide gas.
4. The carbon dioxide gas builds the pressure inside the film canister.
5. Eventually, the pressure inside will pop the film canister lid off.

H₃C₆H₅O₇ + NaHCO₃  ==========>  NaC₆H₅O₇ + H₂O + CO₂ + Heat

Citric Acid + Sodium Bicarbonate ========> Sodium Citrate + Water + Carbon Dioxide + Heat

Because Heat is released during the process, this chemical reaction is called an 

exothermic reaction.

Second Newton's Laws of Motion states F = ma. So, different amount of water or Alka-Seltzer piece will affect the take-off time and altitude of our rocket.

Also, take-off time is affected by the surface area of Alka-Seltzer exposed to water. Crushing it will reduce the take-off time significantly.

Alka Seltzer Blast-off

I was going to do this project for a long time, but just never got around to it. It's simple. It's easy and tons of fun. 

This is what we're building today.

 Simple isn't it? But it's a lot of fun to build and watch it take off.

Supplies List:

• Film canister
• Alka Seltzer tablets (cut into 1/4 pieces)
• Water
• Construction or card stock paper
• Scissors
• Adhesive tape

Let's build our rockets!

Cut a width of 1 1/2 inch to 2" strip and roll it to make a cone. It doesn't have to be perfect. When you get a cone shape, tape it. Now, cut around the bottom to make the cone sit straight up.

Tape the cone on the top of the film canister, with the opening side down.

Now, let's add the fins. You can make them any shape you want, but I went with the traditional triangular shape. This is where you can experiment with different shapes and sizes.

Tape the fins to the sides. Don't worry too much about spacing. Try to make them equidistant and put them on the opposite side of the film canister.

Hold the rocket upside-down and fill it to less than 1/4 way up the canister. It can be as little as 1/8, but you can eye ball it. And as long as it's less than 1/4, it'll work just fine.

Take the rocket outside.

Put a 1/4 piece of the Alka Seltzer tablet into the film canister.

Put the top on it securely.

Put the rocket on a flat surface and wait. 

And wait.

And wait.

And wait.

Waiting felt like a long time. I didn't measure the time, but I think it could be up to 45 seconds or more. My daughter got tired of waiting and tried to check on the first rocket when it went off in her hands. It hurt a little, but no real damage. 

DO NOT HANDLE THE ROCKET UNTIL IT GOES OFF. 

And it will go off eventually.

The rocket is gone.

Although waiting isn't fun, it's much better than getting hurt.

When it goes off, it's powerful and quick. Hard to catch it with your eyes.

The rocket blasted off at 7.44 seconds and flew out of the video frame at 7.58 seconds. Isn't that amazing!

I hope you have a chance to make this one.

Have a great day!