Here is a science experiment that uses antacids to explore acids and bases. We are using it for Deuce's Science Fair entry this year, and also for our chemistry lessons. We are using the book Fizz, Bubble, & Flash! Element Explorations & Atom Adventures for Hands-On Science Fun! by Anita Brandolini, Ph.D. as our core, and this is one of the ideas for further study. It turned out pretty cool, so I've written up an actual science experiment lab sheet for it using a generator at teach-nology.com.
Let's try this link: Antacid Test
If you do this, let me know how you like it.