On June 27th we had some great demos looking at the differences between acids and bases, the density of different things, and last but not least, the vigorous reaction of Mentos and Diet Coke.
The previous night Derek cooked up some red cabbage indicator by boiling chopped red cabbage in water and straining out the cabbage. This reddish/purple liquid was then used to tell the difference between acidic and basic substances. We had kids test vinegar, soap, and baking soda and see how they changed the color of the indicator. They also saw the reaction of the vinegar and baking soda neutralizing each other.
Taking their new acid/base knowledge around the corner, they did some taste-testing to see if certain foods were acidic or basic — sampling baking soda, lemon juice, cocoa powder, and lemon drops.
Then they were also able to play with one-inch cubes of different materials, metals, woods and plastics. There was a cup of water to see how different densities floated or sunk.
In addition to the activities on the tables we had a Diet Coke and Mentos fountain every half hour. Derek was expertly dropping in as many Mentos as he could manage, with the Diet Coke forming a geyser as high as 15 feet. Pretty cool. Check out this link for more information on how it works — here’s a hint, it’s not chemical but physical.