Saturday, March 6, 2010

Adventures in Rocketeering - A Baking Soda And Vinegar, Pop Bottle Rocket

We rented October Sky for our family movie night this weekend - the story of the Rocket Boys of Coalwood, West Virginia.

I thought before we watched the movie, we'd do some rocket building of our own, only on a more child friendly scale, with baking soda, vinegar, and a water bottle.

We actually started out with baking soda and lemon juice, following instructions we found on PBS Kids. First we found a cork that would fit tightly into the neck of a disposable water bottle.

We decorated it with streamers, and a communion glass cone (a paper cone would work too, but the communion glass was handy).

Then, we poured lemon juice, about an inch deep, into the bottle, and filled it up to around the halfway mark, with water.

We wadded 1 teaspoon of baking soda into a square of toilet paper, put on our safety glasses, and moved outside.

The idea was to drop the toilet paper wad into the juice, plug the bottle with the cork, and stand back. Once the paper dissolves, the baking soda is released, it reacts with the vinegar to form carbon dioxide gas, which builds pressure behind the cork, finally shooting it into the air.

That's the theory, and I knew it worked, because we'd done it before when my oldest was three or four, though he has no memory of it.

But, this is what we saw today.

We removed the decorations from the cork, and tried again, only this time with vinegar...nothing.

We switched to a 2 liter pop bottle, noticing our cork was allowing some bubbles to escape from around the edges with the water bottle...nothing.

We added masking tape around the cork, to further seal the bottle...still nothing...we shook the bottle, producing more bubbles inside, but nothing...the children went inside.

Before I cleaned everything up, I examined the bottle. I could still see gas bubbles, and vinegar around the cork, so I figured the gas was escaping, and not building up pressure. I shook the bottle, and laid it on its side. Vinegar dribbled out onto the ground, and thought I'd figured out our problem - we needed a bigger cork. Then, with a wonderful loud popping whoosh, the cork shot forward, and the bottle shot back. It simply took a lot longer than we had anticipated for the gas to build up enough pressure to shoot off the cork.

Of course, we're out of vinegar now, so we'll have to make a trip to the store before the children can try again. In the meantime, they can watch October Sky, which goes perfectly with our new theme for the day Perseverance!

It's great to be a homeschooler.


TEFL Ninja said...

Oh I know somebody who is going to LOVE this.

Great instructions and thanking you in advance for a well chuffed nine year old in the morning ( :

Sarah, British home educating mum in Italy.

Unknown said...

We had a very similar experience this past summer. Except I had read about it taking a while, so when it didn't happen immediately, I picked up the bottle and gave it a vigorous shake. Our lesson for the day was SAFETY. Got quite the bump on my noggin from the bottle flying out of my hands and once it bounced off my head (covering me in vinegar - yes even in my eyes) it flew off down the street and nearly hit a neighbour.

The children enjoyed it quite a bit though, so all for a good cause!

Ticia said...

We did this with our Sunday School one time. It was a huge hit.

Vinegar and baking soda are so much fun.

Natalie PlanetSmarty said...

LOL - I just love it when you describe the experiments that didn't quite work out. At least nobody was hurt, and you can always try again.