To start the program we talked about baking soda and vinegar as separate substances. All of the children had used baking soda to make cookies or cakes, and several had already done the “volcano” activity at home or school. We talked a little about how baking soda helps to make cupcakes rise up while they are baking. I told the children that when baking soda and vinegar are mixed together, they make a gas called carbon dioxide, and the gas being released forms bubbles in the liquid. I then demonstrated. Then I wondered aloud about what we use when we blow bubbles. Soap was one of the answers, so I suggested that maybe if we added soap, the carbon dioxide would blow bigger bubbles using the soap, just like we blow bubbles on a bubble wand. I’m not sure if everyone understood what I was talking about, but they were definitely eager to try it out. Adding the dishsoap significantly increased the volume of bubbles, so it was deemed a success.
The main concept I wanted the children to take away was that mixing the ingredients created a gas, which could blow things up. Our next demonstration of this was to put a balloon on top of a water bottle containing vinegar. We put baking soda inside the balloon and shook it into the vinegar. The carbon dioxide caused the balloon to begin inflating.
Next, we made exploding baggies. We put the vinegar in the baggie, then wrapped baking soda in toilet paper. We then tossed the toilet paper/baking soda bundle into the baggie and hurriedly closed it up tight. The resulting gas blew up the bag enough to make them explode with a loud pop. The toilet paper package is to keep the baking soda from reacting immediately with the vinegar, allowing you time to close the bag up securely before the gas begins to be produced. Children quickly realized that shaking the bag slightly helped to accelerate the mixing of the two substances.
Since several of the children had already experienced a baking soda “volcano”, they were eager to see that recreated. It wasn’t hard to use one of the water bottles, add a little dish soap, and create that classic “volcano” effect. I hesitate to refer to them as volcanoes, because the chemical reaction, flow rates, temperature, etc, are all so different from the real reactions of a true volcano.
After I had demonstrated all of the possibilities, I let the children and their parents interact with the materials on their own, recreating the things I had done or experimenting on their own. This was a very popular Science Storytime, with lots of engagement and interaction.