We found this science project on Kiwico's page and we decided to give it a try immediately. It is a fairly easy to build and fun to watch, but it needs adult supervision and help.
So, what is happening here? We mix baking soda and vinegar and when they get into a chemical reaction, it creates carbon dioxide gas. If this happens inside the boat (plastic bottle) and the only way out for the gas is the little hole of the straw in the back of our boat, it pushes the boat forward in the water.
What do we need?
- an empty plastic bottle
- baking soda
- vinegar
- straw
- scissors
First we insert a small hole in the bottom of the bottle, near to one edge. This is important, because the straw has to be under the water when it is running. I will come back to that later.
This is definitely a grown up step! Our bottle was so rigid, that I ended up warming up the end of a scissors with the help of a candle and this way it was easier to create a hole. Then cut a piece of straw, push it through and seal it with glue or hot glue or some tape. We used normal glue, so needed to wait a few hours to dry.
Important safety note: Do NOT try this experiment without the hole for the straw and do not block the hole of the straw. If there is no way for the gas to escape the bottle, it will cause the bottle to explode!
As a next step, hold the bottle close to level and pour some vinegar. Unfortunately, we had only balsamic vinegar, so it coloured a bit the "fuel" of the boat.
If you rotate the bottle so the straw is at the top, the vinegar will not leak through the straw.
Now holding the bottle really steady, spoon some baking soda close to the top of the bottle, so the vinegar and baking soda does not get into contact as yet. Carefully screw back the bottle cap on. Very quickly tip the bottle to mix the vinegar and soda and immediately place into the water in the bath tub with the straw under the water. You have to be really quick, because the reaction is also very fast.
Now at this point the straw of our boat did not reach the water at all, so although we saw the chemical reaction, nothing happened to our boat, the gas escaped to the air. Our quick fix was that we cello-taped a small battery to the bottom end of the boat and tried again from the step of pouring the vinegar...
And tada... watch the soda bottle to go!
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